THE LF NOTEBOOK #49 - The LOWDOWN, April, 1997 The Mailbag, News and Comments About LF Radio, Etc. John H. Davis, Box 367, Warm Springs, GA 31830 - E-mail - longwave@mindspring.com -World Wide Web http://members.aol.com/lwcanews/ Well, well, well... That's not just an expression. It's literally what I spent a good chunk of column-preparation week working on at the TV station. After 20 years of talking, our county still has no water system, so wells are kind of crucial here. (The phrase could have been "how dry I am," but we finally got it working again. I hope.) Wish I had time and space to fully describe our beautiful, scary, early springtime here. It's been unseasonably warm since late February. By the second week of March, all our trees were at a stage of blooming and leafing more typical of the first week in April. Dogwoods, cherry blossoms, wisteria...they're all out in full glory as I write this. There was a low temperature scare at mid-month, which followed a small but powerful tornado that hit some neighborhoods down in Columbus, GA, and chased me off the mountaintop too. (You'll remember, last time I called March cruel and treacherous.) We seem to have escaped the worst of both circumstances. For our neighbors in the frozen northlands, be of good cheer. Warmth is on the way. This month saw an upturn in correspondence via U.S. mail. In fact, all correspondence was up. We'll postpone some feature material a little longer (sound familiar?); but that's OK. Keep that information flowing! Call To Action Thanks to all who responded to the "help wanted" request for LOWDOWN articles. As you'll see in the mailbag, several are in the works. There's room for more, too. Bear in mind that if you need assistance developing a technical article, you can call on Charles Thurman, our Technical Editor, who is listed on the back page. If you have one that's fully ready for print, send it directly to Bill Oliver. Should you have one written, but would like to have it printed out on a laser printer, I can help with that. And, of course, having a computer file makes it easier to adapt it to the Web. This month, your help is also needed for coordinated natural radio monitoring. Natural Radio editor Dan Levit may have a column this time, and if so, you'll probably find details there. If not, be aware that he's looking for serious investigators to do recordings at specific times. Contact him at the address on the back cover, or by e-mail at: dlevit@cin.net Online Developments We now have about 3 times our original file capacity for the Longwave Home Page, thanks to signing up with a new Internet service provider in this area, and courtesy of some space made available by Pierre Thomson. This means we can tempt newcomers with more articles and features in the archives, and provide even more timely information about radio events for our members. If you checked in to the Web site early this past month, you found information forwarded to us by Jay Miller after last month's issue was already being printed, about the March 7 test of HAARP (the High Frequency Active Auroral Research Project) up in Alaska. While the project beams multi-megawatt HF energy at the ionosphere, the expected effects extend to phase shifts in VLF signals passing through the region, and--the Navy ultimately hopes--generation of ELF signals in the earth-ionosphere resonant cavity. The CW test message was copied across most of the country on 6.990 MHz, albeit with considerable QSB. The 3.3 MHz frequency was buried by a U.S. tropical-band broadcaster. Links were placed on the LW Home Page recently to several parts and kits dealers, including the new Curry Communications home page. In addition, our page sometimes has just-for-fun surprises, like St. Patrick's Day graphics on March 17. The banner at the top of the page is frequently an active icon, which you can click to go to other, non- longwave sites for amusement. If you were to click there right now, you'd see links to sites about Comet Hale-Bopp...an object well worth viewing in person, by the way. Hint: Whenever you access the Longwave Home Page, use the Reload (or equivalent) button on your browser, to be sure you have the latest version of the page. The new service provider also means a new e-mail address is available for reaching me: longwave@mindspring.com. The AOL address still works (mostly) but after my e-mail was accidentally switched off during two different America Online system "upgrades" this month, I agreed with Popeye the Sailor Man: That's all I can stands, 'cause I can't stands no more. It's time for some reliability. The change will not affect how you get into the Longwave Home Page, however. We have quite a collection of interesting Web sites you might want to check out this month. Mark Kahrs found DoD standards for digital LF communciations systems (non-classified) at: http://www-library.itsi.disa.mil/org/mil_stdb/m188140a.pdf Jay Miller says, "While we are out playing with itty-bitty radios, I usually listen to the H-Field portion on the VLF part of the spectrum. It's RF quiet & beautiful in the desert of New Mexico. Notice the up close photo of the VLF array, on the aircraft, that had overflown us." See what he means at: http://www.flash.net/~w5bi/ Member Stan Forsman has written an inexpensive database and logging program for NDB lovers. For details, check out: www.aimnet.com/~caengrav/ndblog/ The new Curry Communication page: http://www.fix.net/~jparker/currycom.htm Look for these and more other links on the Longwave Home Page too. On To The Mailbag -Bart Prater (VA, N4ZV; Smith Mtn. Lake, VA) wrote this month, and notes that postal difficulties may have prevented one or more earlier letters from getting through. He notes, "First, like everyone else, I'm saddened at Ken Cornell's passing--I never knew we even had him to thank for our name, LowFERs/MedFERs." "I've spent most of my time this winter working on the lower sideband exciter I built for my MedFER beacon. Thanks to Todd's listening efforts, I think I've got it pretty well tweaked to the max. Todd has even been able to copy detailed messages without too much difficulty." "Basically, we've found that a very simple filter...just one crystal in series with a common balanced modulator...produces a near-ideal passband for weak signal detection. And, if the output of the balanced modulator is first clipped by nothing more than two cross-connected LEDs, it becomes really potent. Plus, it twinkles when you talk. If my time allows and there's any interest, I may try to write up a brief article this summer." (Your columnist is positive that there's interest in this!) -Todd Roberts (ABC, WD4NGG; Hilton Head Island, SC) has been copying Bart's voice transmissions quite regularly. He adds that Bart is using one of the Radio Shack 20-second voice recorder chips to store and play the messages. Todd hasn't been active much on 1750 meters this year, not having a transmitting antenna to dedicate to LowFER use, but has been testing intermittently weekends on 189.500, "but so far John Hoopes has not been able to hear it near Warner Robbins, GA." He has done quite well listening on 1750, however, netting KRY, JDH, YD, YHO, ZIA, TH, and (probably the most distant) OK this winter. Todd was also one of the folks copying the HAARP CW test transmission on 6.990 MHz in early March. His new 160 meter 200 watt AM rig has been putting some beautiful signals into West Georgia the last few weeks, and he is preparing to bring it up to 300 watts soon. Switching mode finals and a PDM audio stage make it remarkably efficient. This could result in an article on Class E finals for LF/MF use, too. -Lyle Koehler (LEK, MIN, K0LR; Aitkin, MN; k0lr@emily.net) is among the authors now preparing new material for The LOWDOWN. It looks as if we should have some interesting reading this summer! Of course, he's also been listening. "On the LowFER band, OK and TEXAS have been putting in very good signals for the past couple of weeks despite the increase in QRN. Earlier in the season they were only readable in morning hours, but recently they also have been strong during the late evening. At about 0600 CST on Feb. 17th, LowFER BOB became a new log entry (see below). Others heard in the past month are RM, TH, SAM, YHO, and KRY." "STLMO's frequency appears to be holding very steady at 1690.798 kHz. He's sending alternate BPSK and CCW, approximately one minute of each. At MS100, that's long enough to repeat the STLMO identifier six times. The cycle start time may not be synchronized to the exact second with WWV time, but it looks like STLMO is sending CCW during the odd minutes and BPSK/ET during even minutes after the hour. The 10-baud BPSK message uses Bill de Carle's latest Error Tolerant (ET) coding, and is printable here even when the CW signal isn't audible." See Lyle's and Bill de Carle's reception reports of STLMO in the Top End column. "BPSK tests on 80 meters have continued, with QSOs on 3591 kHz most nights at about 0400 UTC. We're still using a keying speed of 40 baud (MS 25 in the COHERENT software). We start out with just plain BPSK and switch to ET coding if necessary when band conditions are poor." "LowFER beacon MIN is temporarily off the air. The neighbor's dog recently developed an interest in radio, and took the fine-tuning coil at the base of the MIN antenna home to examine it more closely. By the time he had finished his examination, there wasn't much left but a flattened plastic bottle which used to be the coil form, and lots of wire strung along the trail. I need to wind a new coil and find a way to keep it out of reach. Either that or wind it on a tabasco sauce bottle." About 1200 UTC on February 17th, Lyle taped BOB, a signal he has been trying to hear for some time. "I was using an IC-751A receiver with an 8-foot loop and homebrew remote-tuned preamp. The receiver has a 500Hz CW filter in the 2nd IF and a 250 Hz filter in the 3rd IF. By tweaking the passband tuning it's possible to get the bandwidth down to about 100 Hz. Most of the recording was made with a modified DSP-59+ filter between the receiver and speaker, with the bandwidth settings at roughly 17 and 34 Hz. The audio filter is bypassed at the very end of the tape. It's almost easier to copy the identifier without the audio filter because of the ringing caused by the static crashes. Signals from (the southeast) sometimes peak about this time of the morning. It appeared signals were fading by the end of my short listening session -- possibly they might have been even stronger a half hour earlier. KRY was still coming in very well, and OK was about the same strength as BOB. The only other LowFER I could hear at the time was SAM, about 100 miles away. It looks like the distance between my location and the center of Mahomet, IL is just over 500 miles. That's a pretty long haul for a LowFER signal. Congratulations, Bob!" -Bob Hoffswell (BOB, AA9DH; Mahomet, IL; BOBharvey@prairienet.org) was especially pleased with Lyle's report and recording. "I haven't had much time to spend listening here this season, and when I have, condx have been really poor. Usually, both BA and YHO are always R5 or better, but since winter set in, their signals sometimes are down to nil. Brice's signal was actually better in August, which is pretty odd, since I'm in the woods with lots of greenery, and Brice didn't have his extra radials in place yet. I still don't have a good RX antenna, however, and just use the beacon's, but did get a path through the woods to try a 1/4-mile wire before the WX got too cold! I've listened for LEK, KRY (who I should get), and OK, with no luck yet. I have the same trouble with PLCs here, and one is now near BA. It's always something, but I sure do like the feel of LF to satisfy the homebrewer in me! When XJ is on, his signal is the best of all, but I haven't been able to catch him for a QSO." Bob remarks on using many of Lyle's circuits in his own work: "(the universal) preamp circuit on my portable set-up, the general-purpose final amplifier in BOB and John Horton's JN Medfer beacon, and the clamp-on current meter for quick checks of antenna and radial currents. (My version uses a spring clothes-pin.) Everything works very well and used up stuff from my junk-box. That's my kind of circuit!" -Bill Cantrell (TEXAS; Haslet, TX; cantrell_bill@macmail1.fwrdc.rtsg. mot.com) advises that he is preparing some articles for publication, and reports, "My wife and I made a quick camping trip to Austin, TX on Tuesday 3/18. Naturally, I took VLF reception equipment along for the ride. I was able to receive the TEXAS beacon in Austin (@ 200 miles) throughout the day, despite thunderstorm interference. My mobile set-up was a 3 foot active whip-antenna feeding a homebrew AD826 dual op-amp preamp (+40 dB) into a Rycom 3135 FSV (I.F. BW = 50 Hz) followed by a homebrew +36 dB gain power-amp/speaker. Needless to say, I was a happy camper." -Mitch Powell (VE3OT; London, ON) has been enjoying the Longwave Home Page, and is another author-in-progress. His article is about 100-foot untuned loop antennas. "These loops are cheap and easy and give outstanding results, so I am sure that someone with trees and no towers or rotors would be interested - and scaling up or down is easy." Mitch uses his big loops, plus a 12 foot Octoloop from the earlier article by Will Payne (who also has an article now on loop antenna sensitivity). "Logging results this winter have resulted in some long haul and new DX. Coast to coast in Canada, with all provinces and NWT - including BC (344-XX Enderby) to NWT (290-YYH Spence Bay) to NFLD (356-AY) - within a 20 minute period. The Atlantic provided 273-SAL and 323-BSD, and out of the Pacific came 367-HA and 280-IPA. The Caribbean and South America provided 26 new ones from this area, including Brazil and many of the islands." "It is interesting to note that 90 percent of the stations logged can be copied on the Octoloop. The remaining ten percent are either not readable at all, or the tone is distorted by ionospherics, threshold flutter or interference. They are then readable on the Big-Loops." -John Reed (jtreed@iamerica.net) has prepared an article describing his synchronous noise blankers (mentioned last month), and we should be seeing it in print soon. He has a few more loggings this month, too: "1687.4 TSN 2/26/97 1223; Fading but good at times. Positive ID. Apparently this beacon is on in the mornings as well as evenings." He has also heard it since that date. "1675.09 D 2/26/97 1229 Solid ID. Heard several times since briefly. Both made with NRD-525 with pre- and post- IF filters (just to add to the confusion)." John is considering writing for Communications Quarterly as well, and reminded me of its address (76 North Broadway, Hicksville, NY 11801-9962) for subscription purposes. He says, "I like the magazine a lot. This latest issue had an excellent article on DSP receivers." A miracle occured, and I was able to obtain a copy, right here in West Georgia. The article in question is by no less an authority than Dr. Ulrich Rhode, and it is indeed fascinating. -One short little note near the end of last month's column generated interest out of proportion to its size. I mentioned that Don L. Davis (dxguy@earthlink.net) had some thoughts on troublesome beacon PYD. It may be just as well that we ran out of room when we did, for Don said his own initial experiences seemed to favor the Victorville, CA, location. He did, however, say that was with very casual observations. His more recent messages point out potential traps in direction finding, especially where metal fences, powerlines, and skywave propagation may all contribute to error. Don went to the site of George AFB in the daytime and found no trace of PYD. This corroborates data from one of our other reliable California correspondents, who prefers not to be quoted, earlier in the winter. It also set Don to rethinking. Having to attend a conference in Las Vegas, he took his dual Ray-Jeff DFs (modified), rifle scope for DF targeting, and precision compass with sights. He has now confirmed to his own satisfaction that "it is located near Groom Lake in Nellis AFB, Nevada. This is the supposed site of UFOs in hangars, aliens, and the usual bunch of brain-dead ideas about classified areas. I took 8 distinct bearings around the periphery of Nellis (about 300 miles of driving!), and was able to pin-point the location to an area about 5 miles west of Groom Lake (115 deg. 56'W, 37 deg. 17'N. I am still in the process of crunching the data - the above is preliminary). My last two bearings were from about 20 miles from the site, and were quite loud, with distinct nulls." "It was a grand adventure - will write up more of what I found (maps, techniques, equipment, etc.) for the LOWDOWN." That should make interesting reading, and may help to set the record straight on the matter. It just goes to show that, even in a hobby based on scientific and engineering principles, there can be uncertainty and even error at times. It's only natural. Fortunately, unlike politics, disputes in science are not ultimately settled by seeing who can shout the loudest, but by laying out our methods and results and letting others see whether they can duplicate them. Don's work is a step along that (literally) long and winding road. Of course, the question a lot of folks would like answered next is, where to send reception reports. Anyone have thoughts on that? -Dave Holland (PX, Berlin, MD; dav3yay@shore.intercom.net) has closed down for the season. "The beacon antenna has been readjusted for 40 meters operations for the summer. Didn't have much of a winter here, which is fine with me. Started to cut grass already. Reception conditions were good this season, for the BC, and Medfer bands, not so good for the Lowfer band. I had some trees in the yard, taken down this winter. This improved the loading of the beacon antenna, and less readjusting was needed with the change in weather conditions." -William Ashlock (WA; ashlocks@mdc.net) was very pleased with the results he obtained from posting a request for Boston area reception reports on the Web site last month. "Thank you for posting my request for Boston area signal reports. The farthest report came from Pocasset, MA, a distance of 65 miles. On another topic, is there interest out there in a discussion of transmitting antenna configurations? One of the questions that comes up is the best location for the loading coil on the vertical element." -Clifford Buttschardt (HDO, K7RR; cbuttsch@slonet.org) has a helpful hint for beacon operators using FET finals. "Apparently Dan's Small Parts has the IRF 510 FET's for sale for a buck each. I realize that Radio Shack is not that much more but I would think the experimenters would like a larger supply than the one and only that usually resides on the RS hook!" -Glenn Jolley (glenn@snmail.jsc.nasa.gov) has been doing some whistler processing "using a freeware program written by a fellow in France, available at ftp.winsite.com/pub/win95/sounds as filename tusf.zip. The program is a little odd, the graphics are not that useful, but the digital filtering algorithms appear to work well." He sent some interesting samples of WAV files processed by the program, then viewed using R.S Horne's Spectrogram program. "I am currently running a magnetometer I designed especially for low level geomagnetic monitoring purposes. I and a few others are interested in coordinating this with natural radio observations. Like a lot of other things we tinker with, the challenge after building the device is finding a place quiet enough to use it effectively. Bob Comfrey is building the magnetometer right now. I also sent a copy to Dan Levit a couple of months ago." -Drayton Cooper (K4KSY, Green Mountain, NC; d4@juno.com) writes, "Thanks to QST, I discovered your web page tonight. Site is great, as is the whole LW hobby. Started in LW listening many years ago with old Navy surplus Scott RCH when I lived on an island off South Carolina coast (Edisto). Still spin the dial down to the basement bands from time to time but now using Ten-Tec Paragon. Was quite active on 160 meters for years (have DXCC on Top Band) so this will give you an indication of my love for the low frequencies. Have bookmarked the site and will spend more time tuning now that I know where to look for signals." He has been contributing valuable loggings to the page, and we will have a later message from him that outlines some of his earlier LF listening experiences in SC. -E. L. "MAC" Mcknight (W7LW@aol.com; Boise, ID) introduces himself, "I've been a ham for 34 years. When I upgraded to extra class 10 years ago I elected to go for a new callsign; I received WK7U. It reminded me then (and now) of a part number off of a motor bearing. The Vanity call program provided the oportunity for me to change this and to express my affinity for a portion of the radio spectrum near and dear to my heart. 73's, W7LW" -John R. (Rick) Wright (R, KA5YWH; Durant, OK) reports that the university has now settled on jwright@sosu.edu for his e-mail address, "and that is supposed to be final; all other addresses are now defunct." "Mark McDaniel brought to my attention that there is a new differential GPS beacon south of Sallisaw Oklahoma on 299 kHz, so I listened for this, with success, using my Kenwood R-2000. To receive this LF beacon I used a long wire, which was matched to the receiver input using a ferrite-tuned coil. I was curious to see what sort of format is transmitted, but the baud rate seems to be wrong for the available options of my FSK unit and ASCII decoder software. Also, The computer puts noise into the receiver, and I will have to move the computer well away from the receiver feedpoint, somehow, if I intend to do anything else with the signal. Does anyone out there know much about the new GPS beacons? Someone should write an article..." "I use a Magellan GPS-2000 hand-held navigation unit in the aircraft, which is more accurate than an aircraft NAV system really needs to be (unless you are talking about a precision ILS!). I fashioned a wooden platform for the Magellan, and a thick rubber band holds it in place. Pushed back under the windshield, it maintains a strong signal, and the NAV display is very easy to use." He remarks that things might have been different for Commerce Secretary Ron Brown and the others on the plane to Dubrovnik, had there been such an instrument available on the Air Force plane. "As for me, I prefer to fly with all instruments running, so that I can crosscheck the readings. Even untralight pilots mount these kinds of receivers (sometimes LORAN-C versions) on their open cockpit aircraft!" -Barry Dieser (bdieser@worldnet.att.net) would like to know: "Does anyone else own an RBA-3 radio? I just powered mine up after it had been off for a very long time. It is still quite an impressive receiver. I have been listening to the Hartford WI beacon (HXF) for the last 2 hours, and there has been absolutely no drift at all. The frequency range of the receiver is 15khz to 600khz. It has very nice filters for CW reception. If anyone knows anything about them, I would like to know where I could get the cable that connects the power supply to the radio. I have been wiring it directly sticking solder tinned wire ends into the plug connectors. Don't know how many of these radios were made, mine has a serial number of 664. I have some manuals for this receiver, and could make some copies for anyone who is interested." -Stan Wilson (ALF, AK0B; St. Louis; microres@crl.com) has been working on his 800 hz BPSK generator. "I went the way of a simple X-OR gate but did not like the discontinuity of switching at other than the zero crossing point of the signal. So, have reworked my circuit to include a couple of D Flip-Flops so that I can now switch at the zero crossing point. I am an OLE rtty operator and we really tried to maintain a coherent signal and never switching at other that the zero crossing. Always believed that it helped to maintain sync on the receiving end." "Anyway it now appears to work on paper and have a few more wires to connect to prove it works correctly and I will have a BPSK generator running. Hope to get enough time this week to prove it all out. Will send you the circuit when I have verified it works ok." "I am cleaning up the 800 hz square wave BPSK signal by filtering with a W3NQN 800 hz filter. Again want a nice clean signal for the SSB input on the xmit. Hopefully the high Q circuit does not go nuts when it sees the phase reversal." "I also pulled one of my old RTTY CRT scopes off the shelf and plan on modifying it so I can use it for BPSK tunning and hope to be able to watch the nice keying pattern on the scope tube. I will feed one set of plates with my local 800 hz oscillator and drive the other set of plates with the incoming BPSK signal from the speaker circuit. As you can see I am an experimenter. Do not work very fast, but usually by the time I get a signal on the air it works correctly. hi My work bench looks like the mad scientist's workshop." -David M. Jones (NR, AD4NR; Columbus, GA; d.jones160@genie.geis.com) writes, "Project INSPIRE has returned my two audio tapes and some spectrograms of the November transmissions from the MIR spacecraft. Bill Pine noted that no reception has been found yet. The Inspire Newsletter should have more details in April." Meanwhile, "I sent a .wav recording of a mosquito to someone at Georgia Tech Research Institute. I suppose he intends to explain how a vlf receiver receives an insect." "Lowfer beacon NR 186.8kHz is off since the tornado (Mar. 13) took down all of the convenient trees to brace it up. At my hamshack, all the backyard trees are down and nothing is left to hang a wire antenna on. I suppose I will build a stealth vertical. I haven't figured out the best antenna solution yet. Verticals I built in the past sacrificed short and medium range." David also sent along pictures of a Tesla coil that we'll either put on the Web site or the Longwave BBS. "George Ensley, the owner of a marine radio dealership in New Bern, NC, has built a beautiful oversize Tesla coil and sent me pictures. It throws corona five feet or so. I have four colorful pictures, one of which shows details; the others, coronas." -Jim Labor (KE4NZG; LABORJ@mail.firn.edu) adds his respects upon hearing about Ken Cornell's passing. "Very sorry to hear that ... definitely inspired by his "Scrapbook" publications. May he live on in the experimental-endeavors of all V.L.F. enthusiasts." -Frank T. Sliwinski (N3MUD, 3213 E. Gaul St., Philadelphia, PA 19134) renewed over the winter and sent along some interesting observations. "I am planning tp install a better antenna to receive VLF. Right now I have a Palomar loop and amplifier, and a MFJ converter for low frequencies. My receiver is a Drake SW-8, thus the need for a converter; only goes down to 500 kHz. Copied a few beacons, but living in Philadelphia, the conditions are not good...too much noise!" "Took the rig to my wife's sister's house over Thanksgiving. She lives in Radnor, PA. Boy, what a difference! Copied beacons I never heard in the city. Ideal surroundings in Radnor. No outside electrical wiring (buried underground), no tall buildings, just trees. Amazing reception." Sounds like Radnor is a truly civilized place, especially from a radio standpoint! Footnotes: We packed in more material than I expected. Miraculously, I think we have now either quoted or made reference to all correspondence that has arrived here this season! If not...and that is always a possibility, given that the postal service and e-mail providers and your columnist are only human...please let me know. Hope you'll get a chance to see the comet in the evening sky soon. Later this month, our southern hemisphere neighbors get so see it, then it's gone for another 4,000 years! Keep the great momentum going--let us hear from you soon. 73. - - -