Vintage Longwave Receivers - Part 4
What to Listen to using Vintage LW Receivers
Past & Present Signals below 500kc
USN VLF Stations: MSK stations NAA, NLK, NPM, NML, HOLT
Alexanderson Alternator 17.2kc station SAQ in Grimeton, Sweden, Ham 630 Meter Operation
LF Noise, Loop and Wire Antennas, Review of the Pixel Magnetic-Shielded Loop
Photo Tour of "The Master of the Pacific" Loran-C Station "M" in Fallon, Nevada (2007)
Photos of the Last Two Operational NDB Stations in Nevada
Inactive NDBs in Nevada, NDB Reception Log
What to Listen to using Vintage Long Wave Receivers
LW Propagation - The time of the year and hour of the day are important to successful DXing on LW. Although in theory LF and VLF propagation is generally considered to be mainly ground wave, most NDBs are actually in the medium wave band (MW) which is 300 kHz up to 3000 kHz. MW does have both ground wave and substantial sky wave propagation characteristics. About the only NDB DX reception is going to happen at night and up to just before local sunrise. Below 100 kHz, ground wave makes up the majority of the signal propagation, however losses due to absorption are highest during the daytime so best signals are usually a nighttime occurrence. Sometimes sky wave will still happen in the LF part of the spectrum and this also adds to nighttime's advantage for better reception. Although you can receive the Navy MSK VLF stations (19kc to 25kc) day or night, weaker LF stations, like JJY at 40 kHz, can only be received just before local sunrise and still nighttime west across the Pacific to Japan.
Due to the sun's position, its affect on the ionosphere and the intense noise generated by the sun's activity, winter nights are always best for reception on LF and MW (in the Northern Hemisphere.) Summer is plagued with countless thunderstorms that add intense noise to the LW spectrum - day and night. Usually by mid-September, the LW signals are getting better and the summer noise is becoming less bothersome. By mid-May, the noise is again increasing to the point where only the strongest signals can be heard. Therefore the best LW DX listening "season" is usually considered to be between the Autumnal equinox and the Vernal equinox. However, strong LW signals can usually always be received at night, regardless of the time of year - but weak LW DX signals will not be heard during summer nights. Also, low noise LW conditions generally occur during sunspot minimum during the 11 year sunspot cycle. Increased solar activity, usually favored for HF DX, increases the band noise on LW. VLF is not usually affected by much of anything which is why it is used for 24 hour, worldwide USN communications. The US Navy MSK stations located around the world are always easy to receive with equipment that can tune low enough - 19kc up to 25kc.
Some of the Signals (Past and Present) below 500KC
Tuning around below 500kc offers some interesting challenges and a different kind of DXing. Nearly all signals encountered are either CW, MCW, RTTY or some kind of data transmission. There are virtually no voice transmissions except for a handful of foreign longwave BC stations. Here are some of the types of signals found below 500kc.
Non-Directional Beacons, NDBs - An enjoyable part of listening below 500kc is receiving the many different Non-directional Beacon (NDB) stations that are located at many airports around the world. Airport NDBs operate continuously, 24 hours a day, seven days a week. The transmissions are nearly always in MCW using a 400hz tone (1020hz was popular in the USA but isn't used anymore.) The NDB station will transmit its assigned call letters in International Morse every few seconds. The NDB ID usually is a three-letter combination that often bears some resemblance to the airport location, e.g., CHD in CHanDler, Arizona. US NDBs that use only two letters for an ID are usually "marker beacons" located at the beginning of a runway. Often, marker beacons are not listed on NAV-AID websites and therefore are sometimes difficult to identify. NDB transmitter power is generally around 25 watts in the USA, however there are some US regional NDBs that run up to 400 watts and a few coastal "transoceanic" and Alaskan NDBs that run 1KW to 2KW. Some Alaskan NDBs also transmit TWEB or "voice weather" in addition to their call in MCW (RWO 394kc Kodiak, AK is one, also OCC 385kc Yakutat, AK.)
Canadian NDBs will follow their station call with a "key-down" signal until the call is sent again. This makes all Canadian NBDs easy to identify. Also, most Canadian NDBs run substantially more power than the typical 25W US NDB, so their NDBs usually put out strong signals. Sometimes Mexican NDBs will proceed the ID with a "long dash" - not "key down," just a long dash, (I have heard this on GRN several times but not on other Mexican NDBs.) NDBs can be found from 190kc up to 529kc. Many NDBs are being "covered up" by powerful DGPS* signals within the same part of the spectrum (generally signals from 285kc up to 325kc are predominately DGPS signals in the Western USA - this changed in 2019 when most of the DGPS nodes were shutdown.) Since the NDB signals are MCW, a carrier is always present on the assigned frequency. With the receiver BFO on, it is easy to locate the NDB carrier and then ID the station when the call is sent. Nearly always, there are multiple NDBs assigned to the same frequency so listening for different characteristics of the transmitted signal becomes part of the method of identification. Also, due to changing propagation, different DX NDBs assigned to the same frequency, will be heard during different listening sessions.
Once the NBD call letters are known, they can be checked against one of the NAV-AID websites. By entering the station ID, the websites will provide the NDB airport location, assigned frequency and sometimes the transmitter power. The best information source is www.classaxe.com/dx/ndb/rna where you'll have to load either the call of the NDB or the frequency of operation into the search parameters and then the page will jump to the listing. You can also scroll down the complete listings of NDBs by frequency of operation. There are also notes regarding certain characteristics for some NDBs as reported by listeners. Classaxe provides the most up to date information on NDBs. Another navaid source for USA, Canadian and worldwide NDBs is www.worldaerodata.com . World Aero Data has almost all NDBs listed but you will have to click on the "Airport Call" to find the actual location. A lot of specific airport information can be gathered from worldaerodata. These two websites provide the "double-check" that is necessary to confirm the NDB ID heard on a specific frequency is the actual station received since there are usually several NDBs with the same call letters but never are identical IDs transmitting on the same frequency. Eventually, a list will have to be maintained in order to know when "new" NDBs are received.
Knowing International Morse - NDBs always send Morse slower than 10 words per minute, so it's not really much of a challenge to copy their call letters, especially since the NDB call sign is sent "over and over and over." When the signal is strong and there's no interference, copy is easy, even if your Morse ability is limited. Can you still receive and identify NDBs if you can't copy Morse at all? More than likely the answer will be yes, mainly because NDBs send so slow and the NDB call is sent "over and over." Since many private pilots were barely Morse proficient (if at all) the intention was that NDBs would send slow enough that the "dots and dashes" comprising the NDB call sign could be written down, e.g.," _.. _.. ._ _. ," and then "translated" into the letters (DDP) that identify the beacon. Also, navigation charts and maps usually had the NDB calls shown for specific airports and the code was written out for that call in "dots and dashes" assuming that pilots weren't Morse proficient. Being fluent in International Morse is a major advantage when trying to copy several NDBs operating on the same frequency. It's also helpful when the signal is so weak that it's practically at the same level as the noise and is fading into oblivion (so you have just one chance to get the call before the signal is gone.) I'm not saying that you have to be able to copy 20WPM in your head while having a conversation with someone else on the telephone but a good code receiving ability will ultimately help fill your NDB log.
Even When You're Morse-Fluent - Every so often you'll come across a NDB sending incredibly bad Morse. From incomprehensible character formation to just plain poor spacing, it all adds up to an almost impossible call sign to copy. Sometimes the poor sending is caused by a problem at the station which is usually repaired in a short time. Other times it's the way that the station call was programmed and it always sends poorly and never changes. Fortunately, this "never changing" problem only applies to a very small percentage of NDBs. Most beacons send excellent Morse but eventually you'll hear a call sign that defies copy. When this happens, copy the call as best you can but be sure to note the frequency of operation. Later, you can use "classaxe.com" to search on "the frequency of operation" to see if the call letters are "rearranged" due to poor spacing. There are several NDBs that have this problem, LDG 296kc is a good example. I've copied this NDB as "DGL" many times because of their spacing problem (the spacing problem has been corrected and LDG now sends excellent Morse, 2019.) Poor character formation is almost as much of a problem with NDBs like MNC 348kc sounding like "NNC" or POY 344kc sounding like "POC." Be sure to log the frequency along with the call. That way you might be able to decipher a questionable call sign when checking your reception list versus the NAV-AIDs. Again though, 99% of the NDBs send excellent Morse.
*DGPS - Differential GPS,...see section below.
|Other Beacons -
There other kinds of beacon signals that will be received on LW.
Sometimes these are marine buoys that provide some navigation or hazard
information in bays, lakes and other waterways. Most oil rigs that are
off shore will have an NDB for their heliport. Also,
ZQ 410kc is a
Canadian Coast Guard Ship, Sir Wilfred Laurier that operates off the
coast of British Columbia. The ship is a light-duty ice breaker that does buoy
and navigational beacon maintenance, escort service, search and rescue
and many other duties that have them at different
maritime locations constantly, thus the NDB, which is for shipboard
helicopter pad (one helicopter is stationed on the ship and there's
for an additional "visitor" helicopter.) Most of the time beacons that aren't
associated with an airport are
next to impossible to find out much information about. If the MCW ID is not listed in
the NAV-AID sites, it does not mean that the signal received is not a
legitimate beacon. Even legitimate airport NDBs sometimes aren't listed
in any of the NAV-AIDs, like some "marker beacons." This can be an
oversight or sometimes it's a new NDB (yes, there are new ones starting
up with some regularity, even today - LYQ in Manchester, TN, for
instance, just started up in 2008.) If the NDB heard is not listed in
the NAV-AIDs, then try a web search on the NDB ID or try some of the web
NDB logs to see if other listeners have heard the same station.
Sometimes, though not too often, complete information on the NDB is
found by this method. Part of the interest in LW listening is receiving
weird and strange signals that are a challenge to identify.
unidentified beacons are regularly tuned in here, INUU 395kc and EEGU
378kc. The latter sends "key down" implying that it is Canadian. Both
are strong signals but are not found on any NAV-AID site or on Classaxe.
On the future of NDBs - Current US regulations state that if an NDB transmitter fails, the airport is not required to repair or replace their NDB station. Every month, more and more US NDBs are "retired" as obsolete technology since there are other more modern navigation signals available that are more accurate. However, many airports do select to maintain their NDBs as the operation costs are negligible and it provides a safety backup if the pilot has problems with his other air navigation equipment. It's up to the airport to decide if they want to continue to provide their NDB signal as part of a tradition of air navigation. Remote airports, especially in Alaska and in the USA along the Canadian border, seem to be more inclined to keep their NDBs in operation.
|DGPS Signals -
DGPS, or Differential GPS, uses a somewhat local transmitter signal that
works with satellite GPS to correct intended errors in the GPS satellite
information. When GPS was being developed there was a concern that an
enemy could use the GPS satellite information to accurately aim and
deploy various types of weapons. To prevent accurate information from
being available directly from the satellite, errors were built-in. These
errors could then be corrected using local transmitters sending
"correction" signals. This initially was for military uses but
eventually also was to allow civilians to utilize the GPS information.
GPS evolved over the years but still the DGPS correction transmitters
are being used. There are 85 DGPS transmitters in the USA (some of which
were converted from the 85 GWEN* nodes by the USCG.) Most are located
along coastlines and some major waterways. Canada also uses DGPS along
its coasts and along the St. Lawrence Seaway. In fact, DGPS nodes are
now located worldwide. There is a specific
frequency band where the DGPS signals are located, 183.5kc up to 325kc.
It depends where in the USA you are located just how much interference
the DGPS signals impose upon reception of NDBs. Here in the Western USA,
most DGPS signals are concentrated from 285kc up to 325kc. There are a
few in the lower part of the DGPS band but the strongest signals are
centered around 300kc (in the West.)
NOTE: Although I hate to admit it, I've used the DGPS signal on 314kc as a receive "test signal" many times. That node is located near Sacramento, California (Lincoln,CA) and it's extremely strong here in Western Nevada. Since I know it's on 314kc and very strong, it makes an ideal "test signal" for the middle of the "NDB Band." When FCH 344kc in Fresno, California shut down (Jan 2018) I no longer had any NDB signal strong enough for daytime copy. Our strong local NDB, NO 351kc in Reno, Nevada, had shut down in August 2013 (and it's really missed.) DGPS 314kc is very strong and does provide a handy "test signal" for daytime use.
UPDATE: Sept 18, 2019 - Just when you find a supposedly reliable signal source, it disappears. The Lincoln,CA 314kc DGPS signal was the last "daytime" MW signal that was strong enough for use as a marker and for test reception. Now it's "history" - along with most of the other DGPS nodes. I did a little checking and it seems that since 2016, the USCG has wanted to shut down the majority of inland DGPS nodes. There was a notice in circulation to allow for public comments dated in 2016. So, this isn't something that just happened. It's been in planning for sometime now. Anyway, about 16 DGPS nodes remain and it appears all others, that is, those that were located somewhat inland from the coasts, were shutdown around Sept 1, 2019. Luckily, there is one node close to 300kc that is still operating. It isn't as strong as the 314kc node but it is daytime copy (barely) here in Western Nevada.
UPDATE LW Season 2019-2020 - Big improvement in digging out NDBs in the 280kc to 325kc region. I've logged many newly heard NDBs in this region now that the DGPS nodes have "thinned out." Not that there still aren't some nodes in operation that are pretty strong, but now there are large "gaps" in the DGPS nodes' operating frequencies that allow hearing NDBs that had previously been covered up.
*GWEN, or Ground Wave Emergency Network, was a LF military communications network that utilized of 85 transmitter nodes located within the USA. Each node consisted of a high power LF transmitter in the 170kc to 190kc part of the spectrum, a 200 ft tall tower/antenna and all of the support gear for providing emergency communications post-nuclear attack. Supposedly, LF was not vulnerable to damage from the EMP of nuclear detonations and could theoretically survive as an operational system. Military and presidential comms to SAC were intended but the system had many problems and, by 1994, had lost funding. The system was eventually shutdown. Many of the nodes were converted to DGPS use.
More Longwave Signals
Longwave Broadcasting - In addition to NDBs, there are foreign longwave broadcasting stations. These are only located in Europe, Africa or Asia. The stations run incredible power levels. One million watts of carrier power is common for longwave broadcast stations. Even though their power levels are extremely high, the signal's propagation faces severe losses and most longwave broadcasting is intended for regional service only. Here in the western part of the USA, it is possible to receive a couple of LW BC stations but those stations are never strong signals and rarely can the program be enjoyed. The strongest and most often received station here is Radio Rossii, located on Sakhalin Island (North of Japan) broadcasting on 279kc at a power level of one million watts. During the winter months in the early morning (~5AM PST,) Radio Rossii is very strong (for LW BC) and can be heard playing Russian pop-jazz music and reading their news service. These are always reports in Russian read by alternating male and female announcers with a short musical interlude between stories. Other LW BC stations are very weak and many times only the carrier can be received, the modulated information being too weak to really understand or even identify. UPDATE 2017: Radio Rossii on LW is gone for good. In fact, all Russian Long Wave broadcasting has stopped as of January 9, 2014. Only a few LW BC stations are active in Asia. Turkey has one and one in Georgia. Apparently these LW stations are too expensive to operate and maintain along with enduring a continuing loss of listeners that have gone to satellite or Internet services.
Longwave Broadcasting's Future - It doesn't look good - Most of Asia no longer broadcasts on LW. Europe has about four stations still operating. The BBC-4 LW station is still running a vacuum tube transmitter and claims when the last tube goes, they are permanently off the air. They claim to have "bought up" all of the spare tubes available in world a few years ago,...and, apparently these tubes can't be rebuilt (more likely the BCC doesn't want to spend the money to have the tubes rebuilt.) When the Irish LW BC station, RTE-Radio One, shutdown a few years ago there was an enormous protest from the Irish in Britain that eventually got RTE-Radio One to reverse their decision to shutdown. The arguments to shutdown all LW BC are based on technology in that higher fidelity programming is available on Medium Wave (AM BC) or FM BC or Satellite or even the Internet. However, ardent LW listeners say "so what?" They don't want to change their listening habits. Even if the LW BC technology has its limitations it doesn't matter since most listeners aren't using new receivers anyway. Many are still using their old vacuum tube radio purchased decades ago. Expensive operation and maintenance cost when power level is at one million watts and the transmitter is of vacuum tube design seems to be the ever present threat that shuts down the LW BC station. At the present, the only thing keeping LW BC alive is their devoted listeners and those include still many maritime listeners. However, the end is probably "in sight" for LW BC. None of the stations want to upgrade their equipment since the future of LW BC is so bleak. Also, in many cases, the real estate that the massive antenna systems inhabit is probably worth more to the governments than maintaining "an obsolete technology" that benefits few and costs them so much to operate.
"Lowfer" is a nickname for the LF enthusiasts that transmit 1 watt signals to 50 foot antennas in the 190kc to 160kc part of the LF spectrum. A license is not required to operate these transmitters because their effective radiated power (EIRP) is so low. The limitations have resulted in very clever ways of extracting very weak signals out of the noise in that particular region of the spectrum. QRSS, or very very slow CW, is one method used. It is so slow that a computer usually monitors the signal for several hours (all night) to assure that copy is possible. Other computer programs are also used to make possible copy of these extremely weak signals. Sometimes, when conditions are favorable, two-way "human" CW contacts do occur but these are rare. Those are usually referred to as "Real Morse Communications" since so much on this particular band is computer driven and monitored for transmission and reception.
Amateur LF Operations - The USA allows hams to operate on 630 meters (472kc to 479kc) in CW or data modes with five watts EIRP. Also, 2200 meters (136kc) can also be used with a limit of one watt EIRP. In other countries, 136kc is a ham band that can be used for fairly high power transmissions although foreign power limits are probably not using EIRP measurements. EIRP is Effective Isotropic Radiated Power and it takes into account that most antennas available to hams will be inefficient on long wave. EIRP allows hams to estimate how much RF power to apply to their antenna based on several physical factors applied to the antenna to achieve five watts effective radiated power. It isn't the actual power input (which is usually much higher) but rather the effective results of that RF power applied to an inefficient antenna. Unfortunately, almost all CW operation on 630M has disappeared. It has been replaced with JT9 signals which consist of a data mode transmission that allows computer program based communications in noisy conditions. Most of the "new" 630M operators apparently didn't know how to receive MW CW signals in RFI noisy urban areas and have gone to data modes instead. The broad bandwidth required for data mode transmissions has displaced all (and there weren't that many) of the 630M CW signals.
Several years ago, 22 experimental licenses were issued by the FCC under the call WD2XSH/xx. These were licensed individuals that are carrying out experimental transmissions around 500kc (usually 508kc.) The limitations were 20 watts EIRP. About half of the 22 licensees eventually got "on the air" but signals were scarce. In the West, WD2XSH/22 in Sweethome, Oregon was very strong and easy to copy. These signals were CW, not MCW. UPDATE: I haven't heard any amateur activity on 508kc for some time now. It seems that the spectrum around 500kc is now being used by commercial or military users. - 2017 UPDATE: Further down this page are more details on the 630 meter and 2200 meter ham bands along with more information on FCC Experimental License Grants - 2017
Loran C - All Loran C stations used to transmit on 100kc. The Loran C signal consisted of a precisely timed series of rapid pulses that both identified the station (as Master or Slave) and also allowed all Loran transmitters to be on 100kc simultaneously. The timing was critical and controlled by cesium-atomic clocks at each station. The shipboard navigation receivers were capable of identifying Master from Slave stations and designed to time the propagation delay based on "knowing" precisely when the pulses were sent and "timing" when they were received. Using the Master signal plus one or more Slave signals allowed the ship's navigation receiver to triangulate the wave fronts and determine their intersection point and the ship's position with an accuracy of around 50 feet, which in the ocean was pretty close. All Loran-C stations were shutdown in 2010 in what was mainly a political move that eliminated the last terrestrial-based, long-distance navigation system in favor of satellite-based GPS navigation. At the bottom of this page is a 2007 photo-tour of "Master of the Pacific" Loran-C Station "M" located in Fallon, Nevada.
Computer Programs - There are several computer programs available that will demodulate many of the data transmission-type LF signals and allow the user to "view" what kind of information is being transmitted. In some cases, weather maps and weather reports can be printed out from NAVTEX. SeaTTY is one such computer program. USN MSK signals can't be decoded without special equipment, data reassembly programs, encoding data and other sophisticated encryption/decryption information.
Amateur Operation on 630 Meters and 2200 Meters in the USA
As usual,...there was a lot of opposition to having US amateurs transmit below 1800kc. It took five years to get FCC approval but still there's some "red tape" in the form of contacting the Utilities Technology Commission for final approval of your intended operation. The ultimate factor in the UTC decision for each individual ham operator will be his station's physical location. Online forms and e-mail makes the process of dealing with the UTC easy.
|GOOD NEWS! - 630
Meter Amateur Band Proposal - As of February 2012, there is a
proposal to create a world-wide amateur band dubbed "630 Meters."
Actually, the proposal is for 7kc between 472kc and 479kc. Initially 1
watt effective radiated power was proposed but there is some indication
that maybe that will be raised to 5 watts EIRP - essentially the
effective power radiated from the antenna. Since nearly all of the
antennas that would be possible for most amateurs to construct would be
short in relation to the wavelength, the efficiency of those antennas
would be compromised. Therefore, even though the EIRP might be 5 watts,
because of antenna inefficiency it might take 100 watts of RF input to
achieve 5 watts of EIRP. There are other restrictions that mostly
involve other countries where interference with NDBs might be a problem.
Also, at the moment there doesn't appear to be any details about the
modes of transmission that can be used. Likely, due to the nature of the
wavelength, transmissions will be restricted to CW or data transmissions
- similar to the 30 meter amateur band in the HF range. The whole
proposal has to still go through several steps to become official so it
looks like the earliest that amateurs might be able to use "630 Meters"
will be early 2013. (I was optimistic at this time.)
Five Years Later - Here's the Process - It's become a fairly easy process to get on 630M or 2200M. As far as the FCC is concerned, general and extra class hams can operate on 472kc to 479kc in CW or data modes and run 5 watts Effective Isotropic Radiated Power, otherwise referred to as EIRP. 2200M is 136kc and the modes are the same but the power limit is 1 watt EIRP. You don't have to contact the FCC about operating either band. The FCC has deferred final approval to the Utilities Technology Commission (UTC.) The UTC is a political lobby concern whose primary interest is to promote business and commerce for the various Utilities. They aren't particularly interested in ham radio unless it adversely affects the operations of the various utility companies. The UTC concern is interference with Utility troubleshooting data and other data that is sometimes on some types of power lines. Whether or not an individual ham would cause interference (at 5 watts EIRP) is dependent on their station's physical location in relation to data-carrying power lines. The UTC requires your station location to be more than one kilometer from any data-carrying power lines. The UTC requires your station antenna location referenced by GPS coordinates in degrees, minutes and seconds. From that information, they either approve your intended LW operation or not. The UTC website provides a form that can be filled out online and sent automatically to the UTC. If you don't hear anything back in the form of an e-mail within six weeks (howcome so long?) then consider that your station location is fine and "you are approved." Assume that you will be contacted by the UTC by e-mail if you are within one kilometer of data-carrying power lines. The online form allows for simultaneous approval for both 630M and 2200M operations.
Here's the link for the UTC online form: https://utc.org/plc-database-amateur-notification-process/
630M Success! - I set up a sked with Mel, K6KBE (QTH: Ione, CA) to see if he would be able to copy my station on 473.5kc. Our sked was for 0600 on March 15, 2018. I was to send CW consisting of "V", "TEST", "de WA7YBS" and QSL information. The transmission lasted about five minutes with all of the text repeated three times. Mel reported his reception to me via e-mail and indicated that he heard me "come on" at 0600 "straight up." RST was 419, which doesn't sound that great but, on 630 meters at a distance of just over 100 miles, that's success. Mel is working on his 630 meter antenna which still needs a loading coil to function correctly. Weather has been his hold up. When Mel is able to transmit we'll go for 2X Morse on 630M.
Successful two-way CW on 630 Meters! - Mel and I set up a CW sked for 0600 for April 2, 2018. Mel was using a homebrew transverter and a "loaded" 75 meter antenna. I called "K6KBE de WA7YBS" at 0600 and Mel came back with a RST 549 signal that sounded strong and in the clear. Conditions were good at this point. Mel gave me a RST 549 also. Next go 'round the QRN started up but copy was still solid. Mel's transmission was that "QRN got u" and he was missing quite a bit of what I sent. Our 73s completed the short QSO. Just over 100 miles and a two-way CW QSO on 473.5khz.
That night, at 2000 PDT, there was a West Coast 630M "get together" on CW 473.5kc. I heard W0YSE tuning up but he was too weak to copy. He was answered by K6KBE and Mel's signal was incredibly strong, 589 or better. I had the loop antenna pointing SW in Mel's direction which obviously helped his signal and was probably why W0YSE was too weak to copy (YSE's QTH is in Washington state, should have been pointing N.) I know,...why didn't I move the loop? A six-foot loop in the house is pretty difficult to reorient.
|Military Transmitters on MW
- Although it's fun to operate the ART-13/CU-32 combo on 630M it isn't the
most comfortable transmitter to use. The problem
is with the sending relays. There are three, the ART-13 sending relay, the
ART-13 vacuum antenna switch and the CU-32 vacuum antenna switch. Each dit or dah actuates these three relays/switches and the resulting din is very
loud and eventually becomes irritating. Sending CW is difficult due to
the distraction of all of the noise going on at the same time. Using
'phones and monitoring the signal helps but, still, who wants a
cacophony of noise going on at 11PM? Unfortunately, most military
transmitters from WWII use the same method of "break-in" keying. The
BC-375/BC-191 uses a rotating sending relay and, since there's only one
relay, it's not quite as noisy as
the ART-13/CU-32 combo. And, speaking of the BC-375,...
Operating the BC-375 on 630M - Requires the TU-26 tuning unit that allows the transmitter to operate on 200kc to 500kc. Also, the BC-306-A LF antenna tuner is needed for operation below 800kc. The antenna I use is a 212 foot long end-fed wire that is comprised of one-half of a "2 half-waves in-phase" antenna that consists of one-half of the 77 foot long 450 ohm feed line and one 135' leg of the antenna. The BC-375 runs about 75 watts output operating on its correct PE-73 dynamotor powered by a PP-1104 (+28.5vdc 50A power supply.) The transmitter actually operates quite well on CW 630 meters. At this low frequency, the BC-375 is very stable with no chirp, blooping or drift.
This station also includes a dynamotor-operated BC-348-Q receiver which has a MW band providing 630 meter coverage. The BC-348-Q actually is quite an impressive receiver with double preselection, three IF amplifers and a crystal filter. A more detailed write-up on setting up, tuning and operating the BC-375 on 630 meters is in our article on "Successfully Operating the BC-375 on the Ham Bands Today" - use the Home/Index for navigation. The BC-375-E and the BC-306-A Tuner are shown in the photo to the right.
UPDATE - May 30, 2019 - Shown to the right is something that I found looking around a local ham's workshop. It's a Radiomarine ET-8043 Emergency Transmitter. It has five tuned frequencies that can be selected by the front panel switch. Each selected frequency can be tuned as desired from 320kc up to 515kc. Power output is 40 watts. The transmitter uses five 1624 tubes. The 1624 is a 1625 with a 2.5 volt 2 amp filament. The circuit is MOPA with audio oscillator and Class B modulation for an output in the A2 mode (modulated CW.) The ET-8043 was originally installed in a Marine Radio Console along with all of the other shipboard radio equipment. Earlier versions of this transmitter had a built-in motor-generator that allowed running the entire transmitter on the +12vdc ship's emergency batteries. This later version utilized a separate (located in the marine console) vibrator power pack for +HV and the ship's emergency battery buss for +LV. All I have is the transmitter. Also part of the console was the keying circuit (a "test key" is on the front panel,) some of the metering, antenna output and other connections that were via the cable that can be seen exiting the lower right side of the transmitter. Unfortunately, the cable is cut. The ET-8043 dates from the early 1960s.
Can the RMCA ET-8043 become a functional transmitter for 630M operation? It's possible although operating A2 wouldn't be bandwidth-friendly even though any mode of operation is legal on 630M. It would be easy to incorporate external A1 or A2 mode switching. An AC power supply has to be built first. Luckily, the plate voltage for 1624 tubes is around 600vdc. Also, since the filaments are wired in series, 12.5vdc at 2A would be required for that supply. More details as this project gets started.
UPDATE: Sept 18, 2019 - Unfortunately, this ET-8043 had been damaged in shipping. I knew this when I bought it from local ham K6OMA. The damage consisted of a bent chassis. No parts were broken, just the bent chassis. I thought it would be easy to just bend the chassis straight again. This hasn't been the case. I've dismounted some parts to ease the process and not risk breaking things. However, the chassis refuses to bend more than just a little. I'm afraid substantial disassembly is going to be necessary and once the chassis is basically "stripped," it can be bent straight using regular "body working" methods. Then all of the removed parts will have to be remounted. Sounds like a winter project.
|Why no more 630M CW Operation?
- The simple answer is QRM. I tried to have a test contact with Andy
KD6TKX in October 2019 but as soon as Andy's call was partially sent a
JT9 data signal came on frequency and completely "covered up" Andy's
signal (which was about RST 549 before the QRM.) Other than a couple of attempts with
Andy, no other CW schedules were requested. Any listening I did only had
reception of JT9 signals. No CW was ever heard during the 2019-2020
season other than KD6TKX. I called CQ on several occasions but never had
anyone reply. Skeds are about all that work and that's subject to data
signal QRM in the CW portion of the band.
The original concept of 630M use was for data transmissions to use the 475kc to 479kc part of the band while CW was to use 472kc to 474kc. Unfortunately, JT9 data signals are now found on all parts of the 630M band which makes any CW contacts impossible. Most of the JT9 users are probably located in fairly high noise areas and probably unaware of the weak CW stations (and their computer program's waterfall display probably doesn't show the weak signals either.) Assuming the frequency is vacant, they start transmitting, even though the proposed use was for CW only in the bottom 2kc of the band. The popularity of digital mode transmissions using ALL of the 630M band has rendered CW contacts impossible.
In addition to JT9 data signals, now SSB voice is being used by some hams on 630M. Unbelievable.
|Effective Isotropic Radiated Power? - Why use Effective Isotropic Radiated Power to set the power limit of 5 watts? This regulation is a method to limit the EM radiation of the transmitted signal to a certain level by control of the relationship of the RF power input to the antenna versus the antenna's physical size and how that size relates to antenna efficiency. Consider that a full-size 630 meter half-wave antenna is over 1000 feet long. This type of "full-size" antenna might actually exhibit a slight gain when compared to an isotropic radiator (dependent on other losses.) Therefore, the power input would have to be 5 watts to stay within the regulations (assuming no other losses.) With a full-size, efficient antenna, even just 5 watts input could result in a formidable signal on CW. However, an antenna that will fit onto a typical city lot will be very inefficient at 630 meters and therefore would exhibit a considerable loss rather than gain. That's how the RF power input to a "small" antenna can be fairly high and yet only result in 5 watts EIRP. Think of the small, inefficient antenna as being like a "dummy load." You can input lots of RF watts into a dummy load and the dummy load does radiate a few feet but it isn't an efficient radiator. So, to stay within the regulations, one has to estimate the efficiency of their antenna and then calculate the amount of RF power input to that antenna versus its efficiency that would result in five watts EIRP. The efficiency is primarily determined by antenna size, antenna height and antenna resistance. There are other variables but it's best to ignore those since they involve soil conductivity, losses due to nearby objects and other things that "vary" all the time. The best info I could find is at www.472kHz.org under "Antennas for 630 Meters" and "EIRP." The formulae are explained in detail and four "real antenna" examples are shown to help answer "the EIRP question" for your particular or proposed set up.|
Licenses - I copied
WH2XVN on 183kc on November 3, 2017 just before 06:00. The
beacon-type signal was in CW and quite strong. Although the signal was
within the so-called Lowfer band it was obvious that the transmitter and
antenna consisted of more than 1 watt to a 50 foot radiator. Although
Lowfers have those limitations, an experimental license allows the
operator much better options for their LW experiments. It's not uncommon
for experimental license grants to be for 20 watts ERP. So,....what
about an experimental license? Read on,....
Experimental License Grants from the FCC are not "amateur licenses." You have to have a specific purpose or experiment that is described in the application. You have to describe your specific location, your station and your antenna within the application. You should be either a college or university,...or maybe a business that does R&D work. In other words,...you need a "good reason" for applying ("amateur communications" is not a good reason.) You can submit your request to the FCC "on line" and the cost is $65. Again,...these are NOT amateur licenses, they are licenses to conduct research, experiments and testing and all of your intended equipment and operation has to be described within the application. Grants are for 24 month periods that can be renewed,...maybe. Time from submitting the application to receiving the grant is from one to three months.
Dealing with LF RFI-Noise
The Longwave part of the RF spectrum can be very noisy with intense static making copy difficult. In an extreme RF noise generating environment maybe all that will be heard is intense "buzzing" any where you tune. These factors can pose anywhere from difficult to solve problems up to impossible to solve problems when using any type of equipment to tune in LW signals. So, does vintage LW gear respond any better or is it actually worse when used in a noisy environment? Most WWII LW equipment will have some kind of noise limiter and also some filtering though they may be of little use against the types of noise encountered today. Fortunately, most of the intense noise found on LW is originating from our own houses. Light dimmer switches are notorious for producing a loud "buzzing" RFI on LW. Certain kinds of controllers that have neon pilot lamps (the orange glowing light) can also create RFI noise. Florescent lighting, certain types of illuminated clocks, computers and monitors, burglar alarms, grow-lamps, "wired" smoke-detectors, switching power supplies including some types of "wall wart" power supplies and some types of CFI lamps - all of these (and probably more) can produce RFI noise. Additionally, modern efficient furnaces that are multi-stage and modulate the blower speed can cause some RFI. This generally is heard as a changing pitch to the RFI as the motor speed changes. The newer the furnace, generally the less RFI will be encountered. RFI is also dependent on how the thermostat controls the blower and burner modulation. Although the list of RFI appliances keeps increasing and sometimes it seems like an impossible challenge, cleaning up our own houses for RFI noise is the first step towards successful receiving of LW DX.
Another noise producer is street lamps - not when they are operating correctly but when they are malfunctioning. Usually before the street lamp goes out altogether it will cycle on and off with a time interval of about 30 seconds to one minute on the start-up cycle. During this time intense RFI is emitted. It's amazing how far away the malfunctioning street lamp can be and still create RFI at your location. Expect intense RFI from a street lamp within your block. Fairly intense RFI from two to three blocks away and nuisance RFI from four to five blocks away. Some receiver noise limiters can reduce the interference but early LW receivers with no filters are useless during the lamp's start-up cycle. Most of the time the failing street lamp will cycle on and off every couple of minutes, all night long. Normally, if you call the power company they will come out and replace the failing lamp. You will have to have the street lamp ID number that is located on the underside of the assembly by the lens and also the street location (the ID number is visible from the ground looking up.) Fortunately for LW listening, the most intense RFI from street lamps is located in the frequency range from about 450kc up to about 4000kc.
Some of the LF RFI noise is on the power lines. There is a tremendous amount of data that is "riding" on the AC power lines. This is in the form of some controlled-carrier information, test and troubleshooting data, time setting information and, in some areas, broadband on the power lines. Some of the data exchanging on the power line is via the "smart meter" that has replaced the old electro-mechanical power meters can also cause RFI. The quieter your receiving area is, the more likely it is that you'll notice some type of power line noise, especially if you use an end-fed wire antenna.
Since there are so many LF RFI noise sources today, especially within urban areas, just about the only practical relief will be by using a tuned-loop antenna. In extremely noisy locations the only solution might be to use a shielded-magnetic loop antenna. The shielded-magnetic loop antenna will use a non-ferrous metal loop-tube that almost entirely encloses the loop antenna wires that are inside. Since the antenna is electrically "shielded" but not magnetically "shielded" it responds mostly to the magnetic portion of the electromagnetic signal. Since most man-made RFI is electrical in nature, that noise is shielded by the loop's enclosure. However, all shielded loops will have some kind of signal amplifier that is either "tuned" or is somewhat "broadband" due to the limited response because of the shielding that almost entirely encloses the antenna itself. In many urban areas, only these types of antennas can provide relief from RFI and allow reception on the lower frequencies. Unfortunately, most commercially-made shielded loops are fairly expensive (~$500 and up.) In less severe noise locations, a simple tuned loop can provide a major improvement over a wire antenna and allow reception of very weak signals. Remember, none of these loops will produce stronger signals at the receiver if compared to a large wire antenna. However, in a RFI-noisy area, the loops will provide a much lower noise level and allow you to hear weaker signals. In a RFI-quiet area, a large wire antenna will provide strong signals significantly above the noise and will probably out-perform a non-shielded tuned loop. But even in RFI-quiet rural areas the improvement in signal to noise ratio along with the directional characteristics that comes with using a shielded-magnetic loop will dramatically improve your LF DX reception.
Non-shielded Tuned Loop Antennas versus End-Fed Wires or Other Wire Antennas
Though LW stations can be tuned in using almost any type of antenna, a fairly large "Tuned Loop" generally provides the user with low noise reception due to its high Q, high selectivity. Another advantage is the ability to null out noise if it is from a particular direction. Most man-made noise will be somewhat directional and possibly could be nulled out. The selectivity of the loop will help with atmospheric noise by increasing the receiver's response to the tuned frequency and increasing the signal to noise ratio. However, the loop antenna must be physically large enough to respond well to very weak signals. Usually three feet up to ten feet is sufficient size for good DX response on MW. Most amplified shielded magnetic loops are about three feet in diameter which is sufficient for the design.
The End-Fed Wire is generally any wire antenna that has no feed line - one end of the antenna connects directly to the receiver antenna input. Usually, EFW antennas are between 75 and 150 feet in length due to physical limitations of the user's property size. Since it's unavoidable that some of the antenna is going to be inside the house, noise levels on EFW antenna are generally high.
Below 500kc, most EFW antennas are going to be "short" and exhibit none of the advantages of typical "long wires" used on HF. However, very long (that is, a few hundred feet long or more) EFW antennas do provide better signal to noise performance than the typical short EFW and in some quiet locations might easily out-perform a tuned loop that's used in a poor location. Extremely long, "Beverage antennas*" perform entirely different (much better) than the typical, short (for LW) End Fed Wire. The EFW's advantage is ease of installation and, even if the antenna is not tuned, it will still give a fairly consistent response throughout the receiver's tuning range. However, because of this wide response and lack of a feed line, it's susceptible to all kinds of noise - made man and atmospheric.
While it's interesting to compare the two antennas, I have found that almost without exception a well-designed, fairly large, tuned loop antenna or an amplified shielded-magnetic loop will always seem to outperform almost any end-fed wire when comparing signal to noise ratio (not necessarily signal strength.) This is especially true with more modern receivers - the newer the receiver's design, the better it usually works with a tuned loop antenna. Very early three-circuit tuner regenerative receivers (1920s) seem to be much happier with long wire antennas of various configurations rather than the relatively small tuned loop antennas. However when using WWII or later vintage receivers, either regenerative or superhet, generally the tuned loop antenna provides the low signal to noise ratio necessary for successful DX NDB station copy.
Be sure to read the next section, "270ft Long Center-Fed Wire Antenna," as this provides an example of what a sizeable wire antenna can do on LW in a RFI-quiet area.
*The Beverage antenna (developed by Harold H. Beverage of RCA) is a one to two wavelength long antenna that is terminated to ground on its far end with a 450 ohms non-inductive load resistor. The Beverage antenna is mounted fairly close to the ground with 3 meters specified, although not too much difference in performance is noted with heights from 6 to 15 feet above the ground. Any higher and the antenna will begin to pick up noise. Beverage antennas are directional off of the terminated end. If the 450 ohm resistor is removed the antenna will become bi-directional off of the ends. Beverage developed the antenna for low noise reception and competitive performance. Two wavelengths is the specified maximum length according to Harold Beverage.
270 ft. Long Center-Fed Wire Antenna
Last year (2016,) I put up a wire antenna that was primarily for 75 meter operation. I wanted to run "two half-waves in-phase" which is basically a 160M dipole antenna operating on 75M. I used 135 feet of wire on each side and fed the center with 77 feet of 450 ohm ladder line. The ends were supported by a counterweight and pulley system erected in some cottonwood trees. Most of the antenna was about 30 feet off the ground but to the south-east the height was up about 37 feet. The center support was 31 feet high. The entire antenna was matched to the transmitter using a Nye-Viking antenna coupler. This system worked great on 75M. I noticed that received signals were generally 20db stronger than with the previous wire antenna (135' Inv-Vee.)
I hadn't thought about using this 270' antenna on longwave until I started restoring a couple of low frequency receivers. The first LF receiver operational was a RBA-1. Since the only sizable antenna available was the 270' dipole, I connected this to the RBA-1. I disconnected the feed line from the Nye-Viking coupler and used a test lead to short the two ladder line wires together. This was then connected to the RBA-1 using a 14 gauge stranded hook-up wire going to the center conductor of the Navy coax fitting (antenna input.)
During the next few days, while I was repairing and aligning the RBA-1, I would test the results using this antenna system. I was completely surprised when I started receiving NDBs from Idaho during the day. The big surprise was the next afternoon (13:30) when I tuned in DC 326kc from Princeton, British Columbia. Finally, when I had the RBA-1 finished I ready to do a serious test the following morning. From 05:55 to 06:35 in the morning I tuned in 47 NDBs in about 40 minutes and five of those NDBs were newly heard ones (#305 to #309 for the total tuned NDBs.) Greatest DX was POA in Hawaii and DB in Burwash Landing in the Yukon. Almost all signals were quite strong and nearly all stations had one or two other NDBs on the same frequency. Another surprise was receiving the first ham signal I'd ever heard below 500kc. WH2XVN in Burbank, CA on 183kc.
To determine if this performance is a result of the antenna or the receiver will require another test. This time using the National RBL-5 receiver.
This antenna forms a "T" which might be considered a vertical with a large top hat. This is the typical antenna used at many NDB sites. Most antennas from the early radio days had a two to three wire horizontal separated with spreaders on each end. Then the center of the "flat top" was tied together and fed with a single wire dropping down to the radio building.
More testing is necessary to determine if this antenna configuration will continue to provide a relatively low-noise operation. Much of the RFI that plagues smaller outdoor antennae and even the tuned-loop (when used indoors) seems to be greatly reduced, especially in the 190kc to 300kc region. I also would like to check if the feed line is shorted at the feed point of the horizontal wires thus making the antenna a true "T" wire, if the performance remains unchanged.
This large wire antenna can be connected directly to a substantial earth ground when not in use. The counterweight system seems to keep the antenna stationary as the wind runs the weights up and down as the tree limbs move around.
More information will be added as I do more testing,... November 5, 2017
UPDATE: While this antenna does provide strong signals, there's been only a few times that conditions are quite. Most noise is in the form of static and bursts. This could be wind noise or nearby storm fronts. With quiet conditions, this antenna is great but those conditions seem to be rare. November 23, 2017
Had great conditions on Dec 23, 2017, 44 stations copied in 40 minutes, one newly heard NBD in LaSalle, MB, CAN, LF-336kc, on the RBA-1 receiver. Best DX - FIS 332kc Key West, FL
The upshot here is,...when conditions are great this 270' x 77' "T" antenna is unbeatable. BUT, if anything does "beat" this antenna, it's noise,...not RFI but atmospheric noise. This is mostly caused by the ionosphere but it can also be weather-related.
Loop Antenna Designs and Performance
Non-shielded Remotely Tuned Loop Antenna Design - My first tuned loop antenna was a ten foot in diameter octagon with 12 turns of 20 gauge stranded wire remotely tuned with variable bias supplied to MVAM-108 varactor tuning diodes. The bias control, or tuning, was located at the receiver position for ease of operation and the bias voltage ran to the antenna via RG-58U coax cable. Tuning range was from 135kHz to 400kHz and by shorting out a turn on the loop the upper end of the range was increased to 500kHz. A 9' diameter single turn pick-up loop was mounted inside the 10' loop and was fed directly to the receiver's antenna input via RG-58U coax. This antenna performed very well with WWII vintage regenerative TRF receivers. Though the 10' loop antenna provided great signals it had a couple of problems. First, due to its size it was non-directional. That might be considered an advantage since I didn't have to provide any method of changing where it pointed. Second, due to its size it had to be located outdoors where it was highly susceptible to strong wind damage. After repairing the wind-broken 10' loop several times, I decided to rebuild the loop into a smaller configuration. This would result in a stronger antenna and would also result in some directional characteristics.
The new loop is a square with four foot sides and six feet across the diagonal. 17 turns are used in the antenna portion of the loop. A separate pick-up loop couples the signal energy from the tuned antenna where it is then routed to the receiver. I initially tried a single turn pick-up loop but found the signals were too weak. This was probably because of the very low impedance of the single turn, its physical length only being about 16 feet. I ended up using a three turn pick-up loop and found this gave much better performance. The pick-up loop is fed with RG-58U and connects to the receiver in use. The loop itself is connected to a small plastic box that contains the varactor diode board, connectors and a switch that selects the tuning range. The loop is tuned by varying the bias voltage (0 to +9vdc) on the varactor diodes. The frequency range is from approximately 195kc up to 440kc in two tuning ranges. This loop antenna is very directional and strong stations that are perpendicular to the antenna axis can almost be nulled out. Since this loop is relatively small, I have it indoors in the same room as the receivers. This location has eliminated the wind damage issue. Rotation is manual and since the upstairs floor is wood, I can set the antenna on the floor with no noticeable losses. In operation, signals received on this indoor 6' loop with a three turn pick-up are just about as strong as the outdoor 10' loop was and since it is directional it has the added advantage of increased signal strength when pointed towards the signal source.
Loop Details: The spacing of the loop wires is not especially critical. About .25" seems to work fine. If the wires seem to get tangled, again, this doesn't really seem to affect antenna performance much. The combs that keep the wires separate are made of .25" thick oak and have sawn notches for the wire mounting. The combs are held in place at the arm's end with glue and screws. To achieve two tuning ranges, I use switched parallel varactor diode sets. The capacitance for a single set is about 30pf to 300pf and a parallel set is about 60pf to about 500pf. The switch is located at the antenna box which would be inconvenient if the antenna wasn't indoors. I use a 9vdc transistor battery as the bias voltage source and a ten turn, 10K pot with some limiting resistors to control the bias voltage to the varactor diode junctions.
Loop Remote Tuning - Shown to the right is a schematic
for a very simple way to remotely tune a loop antenna by using varactor
diodes. As described in the section above, this circuit can be built
into a weather-proof plastic box that can be mounted at the loop. RG-58U
coax cable can be used to connect the box to the remote tuning box that
will be mounted beside the receiver. A standard project box can be used
for the remote tuning box. Battery voltage is provided with a nine-volt
transistor battery and tuning is accomplished with a ten-turn
potentiometer. The remote tuner is also mounted inside a box for ease of
operation. An "ON-OFF" switch is provided to isolate the battery when
the loop is not being used. The coax can be any reasonable length. The
longest I've used is around 50 feet with no problems. You can use PL-259
connectors on the coax and SO-239 box connectors on the remote tuning
box and the loop box. The resistors and the capacitor are not critical
and only provide a filter for the bias supply to the varactor diodes. I
used three turns on the pick-up loop as I found two turns didn't provide
strong enough signals. Best results will depend on the antenna input Z
of your receiver.
To increase the lower end of the tuning range it is possible to switch in a fixed 500pf silver mica capacitor in parallel with the loop terminals. This will reduce the overall tuning spread but will lower the frequency bottom end by about 40kc or so. As shown, the loop tunes 240kc up to 440kc. With a parallel cap switched in, the low frequency is 195kc. If the parallel cap is added a double switching arrangement can be used for better isolation. A higher value cap can be installed to lower the bottom end frequency more if desired but the variable tuning range will decrease as the frequency is decreased. A three position switch (with an off position, too) could be installed to allow a selection of 500pf, 1000pf and 1500pf fixed value capacitors to allow loop tuning to go down to about 150kc or so.
|Additional Loop Antenna
Information as of Jan. 29, 2009: I'm very pleased with
the performance of the six-foot loop. I really think its performance is
at least equal to the ten foot loop that was mounted outside and, many
times, I think it's actually better. During the past two months (12/08
and 1/09) I have logged over 100 new NDBs using the 6' loop. That's not
total NDBs heard - it's just new NDBs I hadn't heard before.
Best DX was YY 340kc in Mont Joli, Quebec at around 2500 miles. Also, in
the other direction, LLD 353kc at Lanai City, Hawaii - also around 2500
miles. Greatest DX wasn't a new NDB for me - it was DDP 391kc in San
Juan, Puerto Rico at around 3500 miles - but DDP is a transatlantic
beacon running 2KW - it's not hard to receive. I think the main
advantage of the six-foot loop is the ability to point it in the
direction of the stations and exclude other stations that are
perpendicular to the antenna axis. LLD is a good example since Reno's
NDB NO is very strong and transmitting on 351kc and LLD is on 353kc. LLD
is a transpacific beacon running 1-2KW and would be an easy copy if NO
was not a local NDB. Fortunately, those two NDB signal paths are
physically about 90 degrees apart at my location so I can somewhat null
NO and copy LLD by pointing the loop SW. Signal levels on the six-foot
loop are about the same as the ten-foot loop was. The receiving
limitations are primarily the atmospheric noise and relative conditions,
then local noise and finally the receiver's ability to pull signals out
of the noise. The RAZ-1 is very good at weak signal detection.
UPDATE - 2015: I've used this loop antenna with many different LW receivers and it seems to work quite well with just about any receiver. When I acquired the Hammarlund SP-600VLF receiver I found that the loop acted differently with respect to the apparent Q of the loop with tuning seemingly so "broad" that it was difficult to find a "peak." I ended up removing one turn on the pick-up loop and with two turns, the loop "peak" could be tuned although it was still somewhat broad. The recommendation is that depending on your receiver input Z you may have to work with the length of the pick-up loop (number of turns) to determine optimum tuning response.
UPDATE - 2018: I've been having trouble with the loop working well with two receivers. The SP-600VLF seemed to make the loop very broad tuning with difficulty finding a "peak." I removed one turn on the loop which helped a little. Then with the R-389, I didn't seem to have enough signal strength from the loop. To try to "fix" the two problems, I've now increased the number of turns on the pick-up loop to four to increase gain. In order to increase selectivity, I've reduced coupling by reducing the size of the pick-up loop. It had been spaced about 1.5" inside the primary loop. I've doubled the distance so now the pick-up loop is 3" inside the primary loop. I'm hoping that the four turns results in strong signals and the greater distance will make the loop "tune" sharper. In a quick test I tuned the R-389 to the nearby DGPS 314kc node as a test signal during mid-day. The loop peak tuning showed 25db on the carrier level meter. As a reference, the 135'x100' "T" outdoor wire antenna showed 40db. The tuning Q didn't change too much but with the R-389 the peak is easy to find. Further testing will reveal if this change benefits DX reception for both the R-389 and the SP-600VLF. November 5, 2018 using the SP-600VLF and the loop I was able to copy NO3M on 473kc. His QTH is Pennsylvania. I'd say the loop works fine with the SP-600VLF. However, the R-389 still favors a wire antenna.
the HP 461A Broadband Amplifier to the Remotely-Tuned Loop
Several years ago, N7ID loaned me a Hewlett-Packard 461A Broadband Amplifier to use with the RAK-7 receiver I was then using for longwave. I installed the 461A between a wire antenna and the receiver. All I got was a tremendous increase in noise and not much, if any, signal gain. I returned the 461A and didn't think about that type of amp again. A few years later I had tried a homebrew solid-state amplifier on my six foot remotely tuned loop but its performance was terrible. It seemed to have so much gain that I'd tune in the AM BC band stations along with various NDBs. Recently, I began thinking about the HP 461A again. When I had used it before, it was an untuned input coming from a random length wire antenna. If I installed the 461A with the loop's pick-up loop as the input that would add the tuned frequency input ability of the main loop along with the pick-up loop's selectivity. This would tend to reduce the amount of noise while enhancing a specific tuned frequency. The output of the 461A would be connected to the antenna input of the receiver.
HP-461A Specs - These small solid state amplifiers had a built in power supply and had selectable fixed gains of either 20db or 40db. Input and Output impedance is 50Z ohms. Frequency bandwidth is 1Khz up to 150Mhz. The input voltage limit is 2vdc and 1vac.
Performance - For the first test I used the Collins R-389 and a 160' End-Fed Wire. This is about as noisy of an antenna that can be found. With the 461A connected between the EFW and the receiver all that seemed to be increased was noise. Signals that were audible disappeared into the noise with 20db of amplification. Next, I substituted the loop antenna and tuned in the DGPS node on 314kc. It was pretty strong with no amplification and very strong with 20db but with 40db of amplification the input overloaded the receiver and the signal seemed to disappear. Returning to 20db and then the 314kc node was again present. At 2230 hours I tuned in NDB MOG 402kc. I showed about 20db on the carrier level meter (a strong signal) without the 461A on. With 20db of amplification, as expected, the meter read 40db. But, if 40db of amplification was selected, then the signal disappeared because the input was so strong that it "blocked" the receiver front end. >>>
Pixel Technologies - Shielded-Magnetic Loop Antenna
Nov. 23, 2019 - I recently had the opportunity to purchase a "used" Pixel Loop Antenna from a fellow LW enthusiast that had two of them. Initially, these loops were built by Pixel Technologies, which was a manufacturing arm of the SiriusXM Satellite Radio business. Nowadays, the loops are a product of "DX Engineering." The one I purchased was an older one built by Pixel Technologies. This loop is a "shielded-magnetic loop" which means that nearly all of the loop is enclosed in a non-ferrous metal tube, in this case, aluminum tubing. The aluminum tends to somewhat shield the loop from certain types of RF noise but, being non-magnetic, allows the loop to respond to the magnetic component of the EM signal. However, this shielding tends to greatly reduce the signal level so an external amplifier is provided to boost the signal level to an acceptable level. There are two advantages to this type of loop. First, it tends to respond less to RFI noise because that type of energy is mostly electrical in nature. This leaves the loop to respond more to magnetic components of the signal. Second are the directional characteristics of the loop configuration. It's possible to enhance a weak signal by pointing the loop in the direction of the signal's origin. It's also possible to null some interferences. This could be either noise or undesired signals. The ultimate goal is that the shielded-magnetic loop will reduce noise and enhance weak signals.
The Pixel Loop has three main components. First is the 38" diameter loop. Second is the broadband low noise amplifier and third is the loop power switch box with wall-wart power supply. The amplifier operates on 24vac provided by the wall wart that connects to the switch box. The 24vac is rectified to provide +20vdc from the switch box. To avoid running a separate power cable to the amplifier the +20vdc is routed up the output coaxial cable simultaneously with the amplifier's output. Since one is an RF signal and the other is DC there's no interaction between the two paths. The amplifier is connected to the loop with a 12" long piece of RG-6 coax. The output coax from the amplifier can be almost any length necessary and it connects to the switch box which is located near the operator and receiver. The output of the switch box connects to the receiver antenna input. There's a power switch on the switch box to turn the loop system on or off. If used in conjunction with a transmitter (operated on it's own transmitting antenna) there's a "keying line" input allowing the loop to "turn off" when the transmitter keying. This prevents over-driving the amp or possible damage. Since the amplifier is broadband, no tuning is required of the Pixel Loop. Frequency range is from 100kc up to 30mc. The loop can be mounted outside or indoors. It can be setup to have a rotator to optimize the directional ability.
|Performance of the Pixel Loop - Dec.
2, 2019 - I've been using the Pixel Loop for a couple of
weeks now and its performance has been quite a nice surprise. The low-noise
amplifier provides enough gain that most signals are fairly close in
strength to what would be heard on a wire antenna. Of course, the large wire antennas will
have stronger signals but also noticeably more noise. It's a trade-off in
that the loop and amplifier will provide enough gain that the advantage
of its lower noise levels will payoff with an increase in the signal to
noise ratio. That does seem to be the case
with the Pixel Loop even when used in a low-noise environment, like rural
Dayton, Nevada. In noisy, urban areas there might be a very apparent
advantage to the shielded-magnetic loop but in this area the advantage
is in directivity and nulling along with very weak signal detection.
I first tested the Pixel Loop with the Hammarlund SP-600VLF and was able to receive DDP 391kc from Puerto Rico to the east and LLD 353kc from Hawaii to the west. I only heard JT9 signals on 630 meters. Performance of the Pixel Loop is much better than my homebrew remotely-tuned loop and much less of a hassle to use. Against the wire antenna, the Pixel Loop doesn't provide stronger signals. The wire antenna provides stronger signals but the noise reduction using the loop is significant therefore the signal to noise ratio is improved with the loop.
UPDATE: Jan 3, 2020 - After using the Pixel Loop in combination with the RACAL RA-17 and RA-237 from November 23, 2019 up to the present, January 3, 2020 (about six weeks,) I've tuned in over 135 NDBs with 13 of those being "newly heard" stations. DX to the west would be both POA 332kc and LLD 353kc in Hawaii. To the east would be DDP 391kc in Puerto Rico along with FIS 332kc in Key West, FL. Canadian stations to the east would be PN 360kc on Anacosti Island which is located just west of Laborador along with several NDBs located on the east shore of Hudson Bay in Quebec. Directivity is great since PKZ 326kc in Pensacola, FL was copied and that's on the same frequency as Canadian powerhouse DC 326kc in Princeton, BC (which was directly off the "side of the loop" so significantly attenuated in signal strength.) The Pixel Loop is a major improvement over my homemade remotely tuned loop.
UPDATE: Feb 20, 2020 - I've been using the RA-17 and RA-237 combo with the Pixel Loop for a little over two months now. Performance is impressive. I've logged over 250 NDBs and of those 31 are newly heard stations (#345 to #375.) Although I don't have a rotor set up (since the loop is indoors) I can rotate it. The nulling effect is very pronounced and allows finding weak NDBs that would be "buried" by an extremely strong NDB on the same frequency. The gain increase by aligning the loop axis with the signal is very good and can increase a 229 signal up to 549. At least enough for solid copy. Lots of 25W beacons from mid and eastern Canada have been copied. One side note, my house furnace uses a modulated blower that always used to create some RFI when running. I had to always listen to MW when the furnace was off. I've noticed while listening in the early mornings that the furnace will come on but I don't hear anything in the receiver. The RFI suppression of the Pixel Loop is amazing.
UPDATE: Feb 27, 2020 - I've noticed that this season has produced 31 newly heard NDBs using the Pixel Loop plus one newly heard NDB on the wire antenna for the Racal set up and then four newly heard NDBs from October 2019 using the wire antenna and the R-389 receiver. The total for this season (so far) is 36 newly heard NDBs. That's almost ten percent of the total number of NDBs I've logged, which is 376, with #376 being YLQ 289kc from La Tuque, QC on the 26th. Also, total number of NDBs logged with the Racal set-up and the Pixel Loop is well over 250 stations, in just a few months of listening. Certainly the Pixel Loop deserves most of the credit for this incredible number of newly heard stations, although the Racal has also proven to be one of the best performers on MW. Another note, the listening session on Feb 26, 2020 also logged FIS 332kc in Key West, FL and several other NDBs from Quebec. Conditions were excellent even though it's getting close to the LW Season winding down.
The Pixel Loop is easy to use, provides a strong signal level with good noise reduction along with the advantages of directionality, both peaking and nulling. New Pixel Loops are somewhat expensive at around $500. But, after using one and being very impressed by its performance capabilities and by its professional level of construction, I can see why the price is what it is.
Headphones versus Loudspeaker
|The final necessity for successful reception of weak LW
signals is using the proper audio output reproducer. If you use a
loudspeaker you can just about eliminate 70% of the NBDs that you would
probably hear if you used headphones. Nearly all of the DX NDB signals
are weak in signal strength. Most signals are in the noise. Much of the
time you are trying to copy the weakest NDB that's on the same frequency
as a couple of strong NDBs. Listening with a set of 'phones enhances
your perception when copying weak signals that are buried in QRM and
Most vintage military LW radio receivers provide a 600Z ohm audio output. Finding a set of 600Z ohm 'phones is pretty easy. If you are looking at the WWII military headsets that provide a short cable with a small phone plug that then plugs into a six-foot extension cable, then you look at the color of the small phone plug shell. If it's red then it's Low-Z or 600Z ohms, if the shell is black then the 'phones are Hi-Z or around 10K Z ohms. This color code only applies to WWII 'phones. Later, in the 1950s, 600Z 'phones were considered Hi-Z, so these types should be measured to verify actual impedance.
Most early vintage LW receivers have high impedance outputs that might have the 'phones connected directly between B+ and the audio output tube plate. You must use Hi-Z 'phones for this type of receiver. Generally the older style 'phones work fine, especially those from the 1920s that were designed for direct B+ to plate connection. >>>
|>>> If the headset is not marked then measure the DCR at the
connecting plug or the phone tips to determine the probable
impedance. Hi-Z phones will measure above 1K ohms DCR while 600Z ohm
phones will measure around 100 ohms DCR. If you measure a very low DCR
(< 5 ohms) then the impedance is 4 or 8 ohms. This test is an
approximation to estimate probable impedance. Remember, 'phone impedance
is "nominal impedance" and dependent on what frequency is used in the
calculation. Generally, nominal impedance meant that the specified Z was
the lowest Z that the would be encountered when the 'phones were used in
a standard configuration listening to average signals at average levels.
Pretty vague,...so don't take the specified Z as something that is
ultra-critical,...close is okay.
Once you have your 600Z ohm 'phones, check the schematic on your
particular LW receiver to see how the audio output is designed. Most
military LW receivers were designed for "headphones only" use and the
600Z ohm audio output is at the phone jack on the front panel (usually.)
Later LW receivers might have the phone jack connect to the 1st AF stage
or the second detector (on a superhet) and it might be that the phone
jack might have circuitry added to assure that the headset is not
"over-driven." Best results will be obtained by connecting the 600Z ohm
'phones to the "actual" 600Z ohm audio output stage. This may or may not
be "at the phone jack" so check your receiver's schematic and connect
your 'phones to the "actual 600Z ohm audio output."
Coast Guard - Loran C Master Station 'M'
NOTE: As of February 8, 2010 the Loran-C system will begin its permanent shut down
On February 8, 2010, I tuned in Loran-C Master Station 'M' at 8:30AM PST and it was operating as usual. Tuning in later in the afternoon, at 5:15PM PST, Master Station 'M' had ceased operating. In August 2010, it was noted that Station 'G,' the last remaining West Coast Loran signal, was not transmitting.
Consider all Loran-C operations "OFF THE AIR"
Fortunately, we toured Master Station "M" in July, 2007 and were able to take several photos of the station including the Megapulse Transmitter and the Control Room - photos and descriptions below...
Update 2021: Fives years after the 2010 shutdown, efforts were underway to develop E-LORAN as a terrestrial-based long-range navigation system. The current views were (and are) that there is an over-reliance on GPS. The GPS signals are not strong and it was becoming relatively easy to disrupt GPS information by jamming, hacking to cause errors and other efforts to compromise GPS navigation. South Korea is starting up its LORAN again (2019 - mainly because of North Korean GPS jamming attempts.) Efforts to establish E-LORAN as the modern replacement for LORAN-C (and a "back-up system" for GPS) are going forward. The new system would still be a terrestrial based long range radio navigation system that would have a consistent accuracy equal to the best achievable accuracy with old LORAN (within 65 feet with E-LORAN compared to within 50ft to 150ft with LORAN-C.)
MORE,...I took two new photos on June 23, 2021 showing the Fallon Master Station Antenna System. Obviously, activities at the station have been on-going since the 2010 shutdown. The signs in Fallon showing U S COAST GUARD - SODA LAKE ROAD are still up, the signs at the station gate are still up and LORAN RD is well-maintained. The only thing I saw different was the old street sign "LORAN RD" had been taken off of the street post (souvenir hunters, no doubt.)
|Just outside of Fallon, Nevada is the U.S. Coast Guard
Loran-C Station which provides a navigation utility for the Pacific
Ocean and the West Coast. Loran-C is part of a world-wide system of
navigation mostly used for sea going craft. The Fallon station is
designated 'M' since it is the Master Control station for the other
three West Coast stations designated 'Y' in Searchlight, Nevada, 'X' in
Middletown, California and 'G' in George, Washington. These three
stations along with the master station in Fallon allow navigators to
determine their position by use of a special Loran C receiver that
accurately measures the pulse characteristics of the received signal to
determine station ID and then accurately measures the time delay of the
precisely timed signal (based on a Cesium atomic clock standard) to
determine the receiver's distance from the transmitter. By using the
master station signal and at least one slave station signal, the
receiver position is determined by timing the two wave fronts to
determine their intersection point in reference to the receiver's
location. If another slave station can be received then the calculation
of intersection point becomes more accurate and likewise the receiver's
position. Various corrections are incorporated into the computations to
allow for skywave propagation (if any,) terrain (over land or over
water) and other minute interferences. Three HP Cesium atomic clocks
keep the accuracy of the system constant since correct timing to the
nanosecond is essential for determining true position. The best accuracy
of Loran C is about 50 to 150 feet.
NEW 2021 Photo left: The Loran C antenna from main gate. The mast is 625 feet tall with each side measuring about six feet across. The capacity hat is about 900 feet diameter and is formed by the 24 top cables drooping down to large isolators. This is a very recent photo that I took on June 23, 2021 showing that Fallon Master "M" station is maintained and staffed.
The transmitter is running 400KW at 100 kHz. The antenna
mast is 625 feet tall and 24 top conductors drooping down to large
isolators form the enormous capacity hat for the system. If you look
carefully at the photo above, all 24 isolators can be seen. Shown in the
photo to the right is a telephoto view of some of the isolators that are
used to prevent corona discharge to the support cables running to the
ground. Each isolator is about twelve feet long. This is also a recent photo taken June 23, 2021.
The LORAN-C signal
consists of a rapid, continuous "tick-tick tick..." centered at 100 kHz.
The signal is actually a pulse train made up of eight pulses from each
Loran C station. The Master 'M' station has an extra pulse in the train
for identification as a "master." Timing is critical as every Loran C
station is on 100 kHz and each station has to send its pulses at a
precise time for the system to maintain accuracy.
The Fallon Loran C is easy to receive anywhere in the west. It is particularly strong in Virginia City as we have "line of sight" to the Loran-C antenna, even though it is nearly 60 miles away. This is because VC is on the east slope of Mt. Davidson at 6200 feet elevation and looking 60 miles east is Fallon at 3980 feet elevation. You can see Mt. Davidson from the Fallon Loran-C Station. The USGC station and antenna are located West of Fallon at the end of Soda Lake Rd. with a right turn onto Loran Rd. to the site.
June 2021 - There's now a geo-thermal plant going further out Soda Lake Rd. which, as you pass Loran Rd., then becomes a dirt road out to the geo-thermal plant.
2007 Photographs Below
Above Left: 2007 photo
of the Antenna System. In this photo the roof of the station house is
just visible and the two street lamps for the parking lot outside the
station house can be seen.
The 625' Antenna base stands on five ceramic insulators. The entire
weight of the tower and guy system is supported by these 5" diameter
insulators. The feed line is an air spaced concentric feedline housed in an
eight-inch diameter PVC tube that exits from the transmitter building.
The box at the end of the feedline is the lightning arrestor. The output
of the feedline connects to the tower base with 2" diameter copper pipe.
The device to the left of the tower is a coupling transformer for the
tower lights - it allows isolation from the AC line if the tower is
struck by lightning. The ground connection can be seen at the base of
the insulators - four copper sheets 2 ft. wide and .125" thick are
buried and also connect to the radial system that is about 900 feet
diameter. For a scale to the size of this installation, the sides of the
tower are 6 feet across. The circular pads at the top of the triangular
section are for fitting spacers to hydraulically jack the entire tower
up for maintenance to the base mount. The "hitching post" in front of
the concrete base is for placement of the ladder to climb the tower.
Since the tower is energized while being climbed the ladder has to be
insulated from ground.
Right: The Control Room with Signal Generators, three Cesium atomic clocks, signal and transmitter monitoring, alarms, communications with slave Loran stations. Everything has a duplicate for redundancy.
Left: The Loran C 400 KW transmitter built by Megapulse. Most of the transmitter consists of sixteen drivers (eight panels on each side) that shape the final output signal. The station can operate with up to two drivers not working. Past the drivers is the output stage followed by the output coupler. The output coupler attaches to the feedline via two large cables (this 8" PVC feedline exits the transmitter building wall and goes directly to the antenna.) The incredibly large switching load on the transmitter power supplies results in a very loud audible representation of the transmitted signal. The two huge power supplies are set up against the two walls of the transmitter building across the isles from each of the transmitter's two sets of driver panel cabinets.
Right: Looking into the rear of the transmitter bay between each of the two driver panel cabinets. The red tags remind the technicians that 30,000 volts is present when the transmitter is operating. Also note the yellow sign regarding the noise present around the transmitter. The bays directly ahead are access to the output coupling which can be seen at the top of the cabinet with the two connections to the concentric feedline output that runs out the wall of the transmitter building to the antenna base.
The output coupler stage of the transmitter. One inductor is hand tuned
for a "rough" setting while the final tune is accomplished remotely with
the motor driven inductor. Below the inductors is the solid state output
magnacoupler. Large capacitance can be used with solid state
transmitters resulting in smaller inductors. These inductors are about
10" diameter. The coils are wound with a cloth covered multiconductor
cable. Note the output cable routed thru the rear fiberglass wall. This is
then routed up to the antenna to feedline coupler that can be seen in
the photo above-right.
The output tank stage which is adjacent to the output coupler. The
tuning inductance is adjusted with a special tool that fits onto the
eccentric knob on the shaft. This allows adjustment with the panel
installed and the transmitter operational. Below are the massive
capacitors that allow the use of smaller inductors. For size reference,
the inductor is about 10 inches diameter.
NOTE: These internal photos
were taken of the standby units. The access doors to the operational
units cannot be removed while the transmitter is running without causing
a system shutdown. Even removing these standby unit access doors would
have triggered an alarm had it not been bypassed in the Control Room
prior to opening.
Thanks to USCG ET1 Chris Shanks for the tour of the facility 7-2007.
Non-Directional Beacon Stations
NDBs in Nevada
Ah,...the good old days, when there were loads of NBDs everywhere,...even in Nevada. Today (2014,) there are no active NDBs in the state. Here's information and some photos of the last two NDBs in operation in Nevada. Both have gone "off the air" in the past few years - AEC 209kc (OTA 2009) and NO 351kc (OTA 2013.) Additionally, I've added information on some of the older NDBs that were operating here in Nevada in the past.
"NO" - 351 Khz - Reno, Nevada - NDB for Reno-Tahoe International Airport
Located on 351 KC is the NDB for Reno-Tahoe International Airport. "NO" runs 25 watts and is a marker beacon physically located at the north end of the airport, in an empty lot, across the street (Mill Street) from the beginning of runway 16R. The antenna is only about 15 feet of vertical radiator with a capacity hat that is about 15 feet off the ground and about 150 feet long. The capacity hat is strung between two "not very tall" telephone poles. The transmitter and climate control equipment are located in and around a small building below the center of the capacity hat. The feed actually enters on the west side of the building through an underground conduit. Coverage is quite good considering the low power of the transmitter and the small antenna. Since "NO" is a marker beacon, it usually isn't listed on any of the NAV-AID sites - but it is operating 24 hrs a day, on 351 KC. About once a year, "NO" is "off the air" for a period of 2-3 weeks. Whether this is due to failures or scheduled maintenance is not known - the signal always seems to return after a few weeks.
"OFF THE AIR"
NO has been off the air for over three months now. This is the longest shutdown yet. Hopefully, NO will return to the air pretty soon. When in Reno last (end of Oct.2013) I drove over to Mill St. to look at the NO site. Everything is still there, the shack, the antenna. Everything appears normal but as of November 7, 2013, NO is still OTA.
No change as of July 1, 2014. Consider NO "Off The Air." See updated photo lower right.
NOTE: As far as I can tell, "NO" was the last operational NBD in Nevada.
photo above: I took this shot of the NO site on September 21, 2015. As can be seen, nothing is left of the NO radio shack, transmitting equipment, antenna or associated structures. The property has been totally cleared. Compare this shot to the shot directly above and it can be seen that the NO shack was located just about center of the view and slightly to the right of the Nugget Towers. I took this shot from the same location behind the auto-repair dealership on Mill St. This pretty much concludes that NO 351kc will not be returning to the air.
"AEC" - 209 kHz - NDB for Base Camp, Nevada
AEC is on 209 kc and can be received here day or night, indicating that the transmitter might be running power higher than the 25 watts normal for NDBs. AEC is located near Warm Springs, Nevada on Hwy 6 about 60 miles east of Tonopah, Nevada. The site is called Base Camp. The antenna is an "inverted L" configuration with the shack located at one end near the pole support. From aerial photos it appears that there are a number of ground radials running out from a central location between the two poles. At one time AEC transmitted voice weather along with the MCW ID, however nowadays just the CW ID is transmitted. Base Camp is a US government controlled, fenced air field with a maintained runway and some minor support buildings. Though the runway was recently repaved, there are large "X"s painted at each end of the runway to indicate "as viewed from the air" that it is closed and not in use. Apparently no hangers are at the site. What the exact use of Base Camp is remains unknown, although once it was part of the Tonopah Test Range. Though some speculate it now has some connection with Groom Lake/Area 51, this is highly unlikely. AEC is not listed on any of the NAV-AID sites yet it is in operation 24 hours a day, everyday. It is listed on LF websites that show logs of received stations.
AEC 209kc has been Off the Air since Sept.2009
Consider AEC "OFF THE AIR"
photo left: AEC at Base Camp, NV - this great photo is by Steve McGreevy N6NKS, from www.auroralchorus.com
Other Nevada NDBs (Inactive)
EMC - 375kc
- Winnemucca, NV - Off the air since 2002
NDB Station Log 2006 to 2020
From Virginia City, Nevada - 2006 to 2012 - A large percentage of the following NDB stations are ones that I copied from Virginia City, Nevada using only vintage, tube-type receivers. I used several different types of vintage LW receivers. Many NDBs were heard using the 1941 RAZ-1 receiver, but I have also copied quite a few with the 1945 RAK-7 and 1944 RBL-5 receivers. I also logged some "newly heard" NDBs during experiments when testing the 1920 SE-1420, the 1922 RMCA IP-501A and the 1940 Hammarlund SP-200-LX receivers. For the 2009-2010 season, I added the 1945 RBA-6 receiver. My first dedicated LW antenna was a 10' diameter remotely tuned loop but that was destroyed by wind. Now, the main LW antenna is a 6' remotely tuned loop located indoors (as of Nov'08.) I also found some new NDBs using various wire antennas. These NDB stations were received during the 2006 to 2012 seasons. Stations are listed alphabetically along with frequency, location and power of the transmitter, if known. Total was 252 NDBs received from Virginia City 2006 up to 2012. NDBs first heard in Virginia City are listed in Black.
From Dayton, Nevada, the new QTH beginning in 2012 We are now in Dayton, Nevada (10 miles SE of Va.City.) For a short time (2013-14,) the antenna used was a 300 ft. long end fed wire up about 50 feet. New NBDs for 2012/13 and 2013/14 seasons are shown in Navy Blue. Receiver was the RBA-6. EFW antenna taken down Mar 2014. Six newly heard NDBs were logged with this combination. Total Spring 2014 was 258
NOTE: The MW-LF Season is from the Autumnal Equinox to the Vernal Equinox, that is, from September of one year to March of the next year.
2014-2015 Season - Nov. 2014, started using Hammarlund SP-600VLF-31 receiver. New NDBs heard with the SP-600VLF are in Maroon. Changed to 6' Remote-tuned Loop Nov.15, 2014.
2015-2016 Season - Started listening Oct. 2015, Hammarlund SP-600VLF-31 and 6' Remote-tuned Loop. Total newly heard NDBs logged (2014/16) with this combination is 35 - Maroon
2016-2017 Season - Hammarlund SP-600VLF-31 w/ 6' Remotely-tuned Loop - First new NDB this season on Nov.30, 2016 (AN-368kc.) Total new with this combo is 42 - Maroon
- Hammarlund SP-600VLF-31 w/ 6' Remotely-tuned Loop -
First new NDB this season on Oct. 13, 2017 (DUT-283kc.) Total new
with this combo is 61 - Maroon
2018-2019 Season - Collins R-389/URR w/ 100' x 135' "T" Wire Antenna - First new NDB this season on Sept. 24, 2018 (ZZP-248kc) Total new with this combo is 15 - Green
- Collins R-389/URR w/100' x 135' "T" Wire Antenna - First
new NDB this season on Sept. 27, 2019 (JNR-382kc) Total new with this
combo is 19 - Green <
= Indicates new this season w/date
2020-2021 Season - RACAL RA-17C-12 w/ RA-237B L.F. Conv. w/ Pixel Loop Antenna. 1st new this season on Oct 3, 2020 (AUB-355kc) New this season 6, new total this combo 38 - Rose < = new this season w/ date
Updated on with Total NDBs logged as of Nov 7, 2020 = 382.
AA - 365kc - Fargo, ND - 100W
ADT - 365kc - Atwood, KS
AE - 351kc - Dudle-Albuquerque, NM
AEC - 209kc - Base Camp, NV - OTA
AFK - 347kc - Nebraska City, NE - 25W
AGZ - 392kc - Wagner, SD
AL - 353kc - Trina (Walla Walla,) WA
AM - 251kc - Amarillo, TX - 400W
AN - 368kc - San Antonio, TX
ANR - 245kc - Andrews, TX
AOP - 290kc -Rock Springs, WY - 100W
AP - 260kc - Denver, CO - 100W
AP - 378kc - Active Pass, BC, CAN
ATS - 414kc - Artesia, NM - 25W
AUB - 355kc -"Saldo"King Salmon, AK <10-3-20PL
AVQ - 245kc - Tucson, AZ
AW -382kc -"Waton" Arlington, WA <2-7-20 PL
AZC - 403kc - Colorado City, AZ
BAJ - 392kc - Sterling, CO
BBD - 380kc - Brady, TX - 25W
BI - 230kc - Jadan-Bismarck, ND
BK - 335kc - CHRLZ-Brookings, SD 25W
BKU - 344kc - Baker, MT - 80W
BM - 375kc - Balmoral, MB, CAN 25W<12-30-19 PL
BO - 359kc - Boise, ID - 400W - OTA
BR - 233kc - Brandon, MB, CAN
BWR - 412kc - Alpine, TX - 25W
BY - 211kc - Beechy, SK, CAN
CBC - 415kc - Cayman Brac, Cayman Islands
CC - 335kc - Buchanan AF, CA - 25W
CD - 362kc - "Dawes" Chadron, NE <1-9-20 PL
CEP- 278kc - Ruidoso, NM - 25W
CG - 227kc - Castlegar, BC, CAN
CH - 329kc - Ashly-Charleston, SC - 400W
CHD - 407kc - Chandler, AZ
CII - 269kc - Choteau, MT - 50W
CIN - 397kc - Carroll, IA - 25W
CKP - 423kc - Cherokee, IA - 25W
CL - 515kc - Port Angeles, WA
CLB - 216kc - Wilmington, NC - 1KW
CN - 235kc - Cochrane, ON, CAN 100W
CNP - 383kc - Chappell, NE - 25W
CO - 407kc - "Petey" Colo.Sprgs, CO 25W >11-7-20 PL
COR - 205kc - Corcoran, CA - 25W
CRK - 389kc - Spokane, WA
CRR - 245kc - Circle, MT - 100W
CRZ - 278kc - Corning, IA - 25W
CSB - 389kc - Cambridge, NE - 25W
CUH - 242kc - Cushing, OK - 25W
CVP - 335kc - Helena, MT - 150W
CY - 353kc - Cheyenne, WY
CYW - 362kc - Clay Center, KS - 25W
CZX - 332kc - Crosbyton, TX
DAO - 410kc - Ft. Huachuca, AZ
DB - 341kc - Burwash Landing,YK,CAN
DC - 326kc - Princeton, BC, CAN
DDP - 391kc - San Juan, PR - 2KW
DIW - 198kc - Dixon, NC - 2KW
DL - 379kc - "Pykla" Duluth, MN <12-20-19 PL
DN - 225kc - Dauphin, MB, CAN
DPG - 284kc - Dugway Prov Gnds, UT
DPY - 365kc - Deer Park, WA - 25W
DQ - 394kc - Dawson Creek, BC, CAN
DUT - 283kc - Dutch Harbor, Amakrak Is., AK
DWL - 353kc - Gothenburg, NE - 25W
EC - 217kc - Cedar City, UT - 25W
EEF - 391kc -"Elephant"Sisters Is., AK < 9-27-19
EF - 206kc - Champion-Castlegar, BC, CAN
EHA - 377kc - Elkhart, KS - 25W
EHM - 385k -Cape Newenham,AK 100W
EKS - 286kc - Ennis, MT - 25W
EL - 242kc - El Paso, TX - 400W
ELF - 341kc - Cold Bay, AK - 1KW
ENS - 400kc - Ensenada, Mexico
ENZ - 394kc - Nogales, AZ - 100W
EOK - 366kc - Keokuk, IA - 25W <2-14-20 PL
ESY - 338kc - West Yellowstone, MT - 100W
EUR - 392kc - Eureka, MT - 100W
EX - 374kc - Kelowna, BC, CAN
FBY - 293kc - Fairbury, NE 50W <1-29-20 PL
FCH - 344kc - Fresno, CA - 400W - OTA
FH - 304kc - Whitecourt, AB, CAN 25W<2-20-20 PL
FIS - 332kc - Key West, FL - 400W
FMZ - 392kc - Fairmont, NE - 25W
FN - 400kc - Ft. Collins, CO
FO - 250kc - Flin Flon, MB, CAN
FOR - 236kc - Forsyth, MT - 25W
FQ - 420kc - Fremont, MN - 25W
FS - 245kc - Sioux Falls, SD - 100W
FS - 375kc - Ft. Simpson, NWT, CAN
GB - 253kc - 'Garno' - Marshall, MN
GB - 419kc - "Babsy"Great Bend, KS 25W >11-7-20 PL
GC - 380kc - Gillette, WY
GDV - 410kc - Glendive, MT - 100W
GEY - 275kc - Greybull, WY
GGF - 359kc - Grant, NE
GHW - 346kc - Glenwood, MN 25W<1-9-20 PL
GLS - 206kc - Galveston,TX-2KW - OTA
GLY - 388kc - Golden Valley-Clinton, MO
GNC - 344kc - Seminole, TX - 25W
GRN - 382kc - Guerrero Negro, Mexico
GRN - 414kc - Gordon, NE
GUY - 275kc - Guymon, OK - 25W
GW - 371kc - Jarpik, Kuujjuarapik, QC, CAN
GYZ - 280kc - Guernsey, WY - 50W
HAU - 386kc - Helena, MT
HBT - 390kc - Sand Point, AK
HCY - 257kc - Cowley, WY
HDG - 211kc - Gooding, ID - 50W
HE - 245kc - Hope, BC, CAN
HF - 241kc - Hearst, ON, CAN 100W
HIN - 275kc - Chadron, NE - 25W
HJH - 323kc - Hebron, NE - 25W
HLE - 220kc - Hailey, ID - 50W
HQG - 365kc - Hugoton, KS - 25W
HRU - 407kc - Herington, KS - 25W
HRX - 341kc - Hereford, TX
HY - 374kc - "Nette" Hays, KS <12-20-19 PL
IB - 209kc - Atikokan, ON, CAN
ICL - 353kc - Clarinda, IA - 25W
ID - 324kc - Idaho Falls, ID
IKY - 429kc - Springfield, KY - 25W
ILT - 247kc - Albuquerque,NM - 400W
IN - 353kc - International Falls, MN
INE - 521kc - Missoula, MT - 400W
IOM - 363kc - McCall, ID - 25W
IP - 201kc - Mobile, AZ
ITU - 371kc - Great Falls, MT - 100W
IY - 417kc - Charles City, IA - 25W
JDM - 408kc - Colby, KS - 25W
JHN - 341kc - Johnson, KS
JM - 396kc - Jamestown, ND
JNR - 382kc -"North River"Unalakleet, AK < 9-27-19
JW - 388kc - Pigeon Lake, AB, CAN
K2 - 376kc - Olds-Didsbury, AB, CAN
L4 - 402kc - Nipawin, SK, CAN - 200W <11-13-19 W
LAC - 328kc - Ft. Lewis, WA - 25W
LBH - 332kc - Portland, OR - 150W
LD - 272kc - Lubbock, TX
LF - 336 - LaSalle, MB, CAN 50W
LFA - 347kc - Klamath Falls, OR
LGD - 296kc - LaGrande, OR - 25W
LLD - 353kc - Lanai City, HI - 2KW
LLN - 266kc - Levelland, TX
LU - 213kc - Abbotsford, BC, CAN
LV - 374kc - Livermore,CA - 25W
LW - 257kc - Kelowna, BC, CAN
LWG - 225kc - Corvallis, OR
LWT - 353kc - Lewiston, MT - 400W
LYI - 414kc - Libby, MT - 25W
LYQ - 529kc - Manchester, TN
L7 - 395kc - Estevan, SK, CAN
MA - 326kc - Midland,TX - 400W
MA - 365kc - Mayo, YK, CAN
MB - 293kc - Mill Bay, Victoria, BC, CAN 25W<2-1-20 PL
MDS - 400kc - Madison, IA - 25W
MEF - 356kc - Medford, OR
MF - 373kc - Rogue Valley, OR
MKR - 339kc - Glascow, MT - 50W
ML - 392kc - Charlevoix, QC, CAN
MLK - 272kc - Malta, MT - 25W
MM - 388kc - Fort McMurray,AB,CAN
MNC - 348kc - Shelton, WA
MNZ - 251kc - Hamilton, TX - 25W
MO - 224kc - Moosonee, ON, CAN <1-29-20 PL
MO - 367kc - Modesto, CA - OTA
MOG - 404kc - Montegue, CA - 100W
MR - 385kc - Monterey, CA
MW - 408kc - Moses Lake, WA
NA - 337kc - Orange County AP, CA
NM - 278kc - Matagami, QC, CAN
NO - 351kc - Reno, NV - 25W - OTA
NY - 350kc - Enderby, BC, CAN
ODX - 355kc - Ord, NE - 25W
OEG - 413kc - Yuma Proving Grounds, AZ
OEL - 381kc - Oakley, KS - 25W
OIN - 341kc - Oberlin, KS - 25W
OJ - 239kc - High Level, AB, CAN
OKS - 233kc - Oshkosh, NE - 25W
OLF - 404kc - Wolf Point. MT - 100W
ON - 350kc - Newport, OR
ON - 356kc - Penticton, BC, CAN
ONO - 305kc - Ontario, OR
ORC - 521kc - Orange City, IA - 25W
OT - 378kc - Bend, OR
OUN - 260kc - Norman, OK - 25W
OWU - 329kc - Woodward, OK
PA - 347kc - Prince Albert, SK, CAN
PBT - 338kc - Red Bluff, CA -400W OTA
PBY - 259kc - Kayenta, AZ
PD - 230kc - Pendelton, OR - 400W
PDG - 327kc - Watsonville, CA - 25W
PFT - 342kc - "Piney" Pinecreek, MN <1-31-20 PL
PG - 353kc - Portage, MB, CAN
PI - 383kc - Tyhee, ID
PKZ - 326kc -"Pickens"Pensacola,FL400W<1-1-20PL
PMV - 329kc-Plattsmouth,NE 25W <11-23-2019 PL
PN - 360kc - Port Menier, Anacosti Is., QC, CAN
PNA - 392kc - Pinedale, WY - 25W
POA - 332kc - Pohoa-Hilo, HI
POH - 428kc - Pocahontas, IA - 25W
POY - 344kc - Powell, WY
PPA - 450kc-Puerto Plata, Dominican Republic
PR - 218kc - Prince Rupert, BC, CAN < 9-30-19
PRZ - 407kc - Portales, NM - 25W
PTT - 356kc - Pratt, KS - 25W
PY - 207kc - Ft. Chipewyan, AB, CAN
PYX - 266kc - Perryton, TX - 25W
QD - 284kc - The Pas, MB, CAN
QL - 248kc - Lethbridge, AB, CAN
QN - 233kc - Nakina, ON, CAN
QQ - 400kc - Comox, Van.Is., BC
QR - 290kc - Rigina Int'l, SK, CAN
QT - 332kc - Thunder Bay, ON, CAN
QU - 221kc - Grand Prairie, AB, CAN
QV - 385kc - Yorkton, SK, CAN
QW - 302kc - North Battleford, SK, CAN
RA - 254kc - Rapid City, SD - 100W
RD - 367kc - Redding Muni, CA - 25W
RD - 411kc - Redmond, OR - 400W
RG - 274kc - Red Wing, MN 25W <1-29-20 PL
RG - 350kc-Will Rogers World AP, OKC,OK
RJ - 378kc-Roberval,QC,CAN 500W<12-30-19 PL
RL - 218kc - Red Lake, ON, CAN
RMD - 204kc - McDermitt, OR - 25W
RNT - 353kc - Renton, WA - 25W
RO - 305kc - Roswell, NM - 400W <1-1-20 PL
RPB - 414kc - Belleville, KS
RPX - 362kc - Roundup, MT - 25W
RWE - 528kc - Camp Roberts, CA
RWO - 394kc - Kodiak, AK - TWEB Voice WX
RYN - 338kc - Tuscon, AZ - 400W
SA - 356kc - Sacramento,CA
SAA - 266kc - Saratoga, WY - 25W
SAK - 515kc - Kalispell, MT - 25W
SB - 397kc - San Bernadino,CA
SB - 362kc - Sudbury, ON, CAN
SBX - 347kc - Shelby, MT - 25W (sends SDX or UDX)
SC - 271kc - Stockton,CA
SCO - 283kc - Scobey, MT
SDA - 411kc - Shenandoah, IA - 25W
SDY - 359kc - Sidney, MT - 25W
SF - 379kc-San Francisco Intn'l AP, CA
SG - 341kc - Santa Fe, NM
SIR - 368kc - Sinclair, WY
SIT - 358kc - Sitka, AK > 10-8-20 PL
SKX - 414kc - Taos, NM - 25W
SL - 266kc - Salem, OR - OTA (now SLE)
SLB - 434kc - Storm Lake, IA - 25W
SLE - 266kc - McDerrmit AP, Salem, OR
SM - 230kc - Metre/Sacramento, CA
SM - 254kc - Fort Smith, NWT, CAN
SOW - 206kc - Show Low, AZ - 25W
SRL - 270kc - Santa Rosalia, MEX
STI - 333kc - Mt. Home, ID
SU - 414kc - "Salix" Sioux City, IA 40W >11-7-20>PL
SWT - 269kc - Seward, NE - 25W
SWU - 350kc - Idaho Falls, ID
SX - 367kc - Cranbrook, BC, CAN
SYF - 386kc - St. Francis, KS - 25W
SYW - 428kc - Greenville, TX - 25W
SZT - 264kc - Sandpoint, ID
TAD - 329kc - Trinidad, CO
TCY - 203kc - Tracy, CA
TF - 373kc - Pueblo, CO
TH - 244kc - Thompson, AB, CAN
TK - 392kc - Telkwa/Smithers, BC, CAN
TOR - 293kc - Torrington, WY
TQK - 256kc - Scott City, KS - 25W
TV - 299kc - Turner Valley, AB,CAN
TVY - 371kc - Tooele, UT - 25W
TW - 389kc - Twin Falls, ID
U6 - 360kc - Creston, BC, CAN
UAB - 200kc - Anahim Lake, BC,CAN
UK - 371kc - Kearn, CA
ULS - 395kc - Ulysses, KS - 25W
UNT - 312kc - Penticton, BC, CAN
UVA - 281kc - Uvalde, TX - 25W
VC - 317kc - LaRonge, SK, CAN
VG - 230kc - Vermillion, MB, CAN
VQ - 400kc - Alamosa, CO
VT - 332kc - Buffalo Narrows, SK, CAN
VTR -350kc-Takotna River, McGrath, AK<2-1-20 PL
VV - 326kc - Wiarton, ON, CAN 400W<1-9-20 PL
WC - 332kc - White Rock BC,CAN<2-18-20 PL
WG - 248kc - Winnepeg, MA,CAN
WL - 385kc - Williams Lake, BC, CAN
XC - 242kc - Cranbrook, BC , CAN
XD - 266kc - Edmonton, AB, CAN
XE - 257kc - Saskatoon, SK, CAN
XH - 332kc - Medicine Hat, AB, CAN
XJ - 326kc - Fort Saint John, BC, CAN
XS - 272kc - Prince George, BC, CAN
XT - 332kc - Terrace, BC, CAN
XX - 344kc - Abbotsford, BC, CAN
X2 - 328kc - Athabacsa, AB, CAN < 9-30-19
YAG - 376kc - Fort Frances, ON, CAN
YAT - 260kc - Attawapiskat, ON, CAN
YAZ - 359kc - Tofino,Van.Is., BC, CAN
YBE - 379kc - Uranium City, SK, CAN
YBL - 203kc - Campbell River, BC, CAN
YBV - 370kc - Berens River AP, MB, CAN
YC - 244kc - Cranbrook, BC, CAN
YCD-251kc - Nanaimo, Van. Is, BC, CAN
YCO - 375kc - Kugluktuk, NU, CAN
YD - 230kc - Smithers, BC, CAN
YE - 382kc - Fort Nelson, BC, CAN
YEK - 329kc - Arviat, NU, CAN 500W <12-13-19 PL
YEL - 276kc - Elliot Lake, ON, CAN
YER - 334kc-Fort Severn, ON, CAN 195W <12-8-19 PL
YFM - 332kc-LaGrande 4,QC,CAN 2KW <12-5-19 PL
YHD - 413kc - Dryden, ON, CAN
YHN - 329kc - Hornepagne, ON, CAN
YIV - 300kc - Island Lake, MB, CAN
YJ - 200kc - Victoria Island, BC, CAN
YJQ - 325kc - Bella Bella, BC, CAN
YK - 371kc - Yakima, WA
YK - 269kc - Castlegar, BC, CAN
YKA - 223kc - Kamloops, BC, CAN
YKQ - 351kc - Waskaganish, QC, CAN
YL - 395kc - Lynn Lake, MB, CAN
YLB - 272kc - Lac la Biche, AB, CAN
YLD - 335kc - Chapleau, ON, CAN
YLJ - 405kc - Meadow Lake, SK, CAN
YLL - 241kc - Lloydminster, AB, CAN
YLQ - 289kc - La Tuque,QC,CAN 500W<2-26-20 PL
YMW - 366kc - Maniwaki, QC, CAN
YNC - 385kc - Wemindji, QC, CAN 25W <1-27-20 PL
YNE - 207kc-Norway House,MB,CAN 1KW<12-10-19 PL
YPH - 396kc - Inukjuak, QC, CAN
YPL - 382kc - Pickle Lake, ON, CAN
YPM - 274kc - Pikangikum, ON, CAN
YPO - 401kc - Peawanuck, ON, CAN
YPW - 382kc - Powell River, BC, CAN
YQ - 305kc - Churchill/Eastern Creek, MB, CAN - 500W
YQA - 272kc - Muskoka, ON, CAN
YQF - 320kc - Red Deer, AB, CAN
YQK - 326kc - Kenora, ON, CAN
YQZ - 359kc - Quesnel, BC,CAN
YSQ - 260kc - Atlin, BC, CAN
YTL - 328kc - Big Trout Lake, ON, CAN
YWB - 389kc - West Bank, BC, CAN
YWP - 355kc - Webequie, ON, CAN
YXL - 346kc - Sioux Lookout, ON, CAN
YXR - 257kc - Earlton, ON, CAN 400W
YY - 340kc - Mont Joli, QC, CAN
YYF - 290kc - Penticton, BC, CAN
YYU - 341kc - Kapuskasing, ON, CAN
YYW - 223kc - Armstrong, ON, CAN
YZA - 236kc - Ashcroft, BC,CAN
YZE - 245kc - Gore Bay, ON, CAN
YZH - 343kc - Slave Lake, AB, CAN
ZAB - 214kc - Leduc/Edmonton IAP, AB, CAN
ZEG - 379kc - Edmonton, AB, CAN
ZF - 356kc - Yellowknife, NWT, CAN
ZKI - 203kc - Kitimet, BC, CAN
ZQ - 410kc - Sir Wilfred Laurier CCGS*, BC, CAN
ZP - 368kc - Sandspit, Queen Charlott Is, BC, CAN
ZPA - 372kc - Prince Albert, SK, CAN 25W <12-20-19 PL
ZRG - 414kc - Regina, SK, CAN
ZSJ - 258kc - Sandy Lake, ON, CAN
ZSS - 397kc - Yellowhead-Saskatoon, SK, CAN
ZT - 242kc - Port Hardy, BC, CAN
ZU - 338kc - Whitecourt, BC, CAN
ZVR- 369kc - Vancouver (Sea Is.,) BC, CAN
ZXE - 356kc - Saskatoon, SK, CAN
ZYC - 254kc - Calgary, AB, CAN
ZZD - 308kc - Calmar/Edmonton Int'l AP, AB, CAN
ZZP - 248kc - Sandspit, Queen Charlotte Is, BC, CAN
Z1 - 305kc - Three Hills, AB, CAN 25W <12-8-19 PL
Z5 - 274kc - Vulcan, AB, CAN
Z7 - 408kc - Claresholm, AB, CAN
3Z - 388kc - Taber, AB, CAN
4W - 391kc - Kelsey, MB, CAN 25W<1-23-20 PL
5J - 328kc - Coronation, AB, CAN 141W<1-9-20 PL
6T - 362kc - Foremost, AB, CAN
9Y - 311kc - Pincher Creek, AB, CAN - 50W
INUU - 395kc - 11/2017 (also in 2016, 2019)
EEGU - 378kc - "Key Down-CAN?" - 11/2017,
OTA - Off The Air, Decommissioned
* Canadian Coast Guard Ship - NDB for heliport onboard
** not counted in total received
|Henry Rogers WA7YBS ?November 2007, new info added Oct.2008, Nov. 2008, Jan 2009, Nov 2009, updates Sept 2014, updates Jan 2015, update on "NO" 351kc with photo Sept 2015, updates on LW BC, 600M ham, RBA-1 rcvr Oct 2017, info on DGPS, GWEN, FCC Experimental License Grants, Nov 2017, added R-389 info Jan 2018, Layout Revamped to four parts in Feb 2019, added Pixel Loop info Dec 2019,|
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Western Historic Radio Museum
Vintage Radio Communication Equipment Rebuilding & Restoration Articles,
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