The L. F. Notebook - Mailbag, News and Comments (From The LOWDOWN, July, 1996) John H. Davis PO Box 367 Warm Springs, GA 31830 -E-mail - johnhdavis@aol.com -Fax - (706) 672-0964 -Longwave BBS - 706/672-0360 -Web http://users.aol.com/lwcanews/ It's a summer of fun and games for some, and of work and games for others, here in Georgia this year. The annual Georgia State Games are underway as I write this, and will be wrapping up as many of you read it. Then the world comes to Georgia for the Centennial Olympic Games later this month. Finally, the Paralympic Games follow the Olympics in August, also in Atlanta. When some folks first heard that the Olympics were slated for Atlanta, you could see the dollar signs popping up in their eyes. Landlords began making plans to kick out their tenants and rent housing to visitors at exorbitant rates...not just in Atlanta, but way out here in the wilderness. Merchants all over the state began sprucing up their junk shops--er, antiques and crafts emporiums, in hopes that droves of Olympic visitors would be passing through. Cafes stocked up on grease and green tomatos, to better inflict stereotypical Southern "home" cooking on unsuspecting wayfarers. Fortunately, a healthy dose of reality has set in by now. When you come to Georgia this summer...and I hope at least some of you will be doing so... you'll find a modern state, full of friendly people, ready to do whatever they can to make your stay more pleasant. (Possible exception...the Interstate highways in and around Atlanta are inhabited by lunatics, and there's no reason to believe that will change any time soon. Exercise caution there.) Not all Olympic venues are in Atlanta, of course. They range all the way from the Atlantic coast for yachting, to the west end of the state, where Columbus will host women's fast-pitch softball. Your columnist is about halfway between Columbus and Atlanta, and so has been surrounded by "Olympic fever" for years. Residents of this area have already received most of the financial and social benefits of the Olympics that they will have. This has been a very popular area for teams from around the world, who wanted to train for the upcoming games in the same climate where they will have to perform this summer. Several nations' track and field teams prepared in the city of LaGrange, northwest of here. The French equestrian team practiced about 15 miles away. And the Paralympics team from the Netherlands are being hosted at the Roosevelt Warm Springs Institute for Rehabilitation, right in downtown Warm Springs. So, although I haven't mentioned the whole thing very much in previous columns, I'm certainly going to take this opportunity to do so, and welcome the world to Georgia! The graphic at the head of this column is supposed to serve a dual function...honoring Independence Day, and, through the stars above Liberty's torch, reminding you in a redolant way (not intended to infringe upon any trademarks of the IOC, USOC or ACOG, whatsoever, amen) of the Atlanta Olympic logo. Thus, the whole United States symbolically welcomes the world here for the occassion. In the graphics, I've also tried to include flags from most of our members' homelands, although I apologize if some of them are hard to distinguish in black-and-white printing. This month's column will be available on our Web page, if you'd like to view everything in color. (**COLOR versions of this column, with graphics, are available on the BBS. See ALLFILES.TXT for the particular file names.) Product Review: Ramsey FM-25 Kit Several months ago I mentioned having bought a Ramsey FM-25 stereo FM transmitter kit. This is the review that I bumped from last month's column due to space. Ironically, one of the larger circulation electronics magazines (I believe it was Electronics Now, but I'm not positive) chose that same time to review the kit. So, you can have the advantage of both this review and theirs. Unlike earlier models, the FM-25 is frequency-synthesized, so drift is not a problem in applications such as signal relaying from remote receiving sites to one's radio shack. Construction of the unit went fairly smoothly. Precise setup of stereo could be a bit awkward without an FM broadcast modula- tion monitor, though, because modulation sensitivity varies with adjustment of the oscillator tank coil. However, it's possible to get modulation sensi- tivity fairly close with a voltmeter, using the adjustment procedure in the booklet. On a spectrum analyzer, the signal is cleaner within the FM band than one might expect from relatively simple gear, but there was a distinct spur at 20 MHz. I haven't yet determined the source. I use a 1/4-wave shorted stub at carrier frequency to reduce even-order harmonics from the output, and that shorts most of the spur as well. While audio sounds clean with the furnished AC adapter, it produces visible broadening of the carrier when viewed on the spectrum analyzer. It's much cleaner with battery power, or if one adds addi- tional filter capacitors. I found range to be surprisingly good in some directions, and surprisingly bad in others...just a consequence of VHF propagation among trees and buildings, of course. I couldn't get reliably noise free reception from my hopeful LF receiving site back to the house, a distance of about 300 feet, even in mono. But with the transmitter on the roof of the house, and the same receiving antenna (a Radio Shack 4-element VHF TV antenna) taken out in the field, I was able to pick up perfect stereo almost 1,000 feet away in another direction. That particular spot would be nice for LF and MF transmitting antennas, if I can get the OK for it. Consider the possibility: If I replace the 38 kHz crystal with a source derived from a frequency standard, the 19 kHz stereo pilot could be used as a frequency reference in the field. Then, if I use the left and right channels to key or otherwise modulate my LF and MF transmitters, it would be possible to link my home to two CCW, BPSK, and/or voice beacons, entirely by radio. Drawbacks to this idea are (a. lack of time for that much construction just now; and (b. there are exactly two FM channels in this area sufficiently quiet to use, and one never knows how long that will last. But the idea certainly fires the imagination! The transmitter has had immediate practical uses. It has been helpful setting up satellite dishes, where I needed a means of relaying audio from indoors out to the dish. Ramsey has added an audio processor kit to their product line, suitable for their AM and FM transmitter kits. It might not be too useful for our purposes in signal relaying, but it would help in distributing music around the house...which is what most (i.e., normal) people presumably do with it. And, there's now a deluxe version of the kit with audio processing built-in. Disc(o) Fever Irdial-Discs in London sent word at the end of May that pre-release distribution of Electric Enigma, the 2-CD set of Steve McGreevy's recordings of whistlers, auroral chorus, and related natural-radio phenomena, was anticipated for June 4. The distributor is THESE Records, 112 Brook Drive, London SE11 4TQ, England (Telephone 44+171+587+5349; Facsimile 44+171+582+5278). The record company have established an excellent Web page that not only describes the recordings, but also provides additional useful information on natural radio. The URL is http://www.ibmpcug.co.uk/~irdial/vlf.htm For further information, contact: Irdial-Discs, PO Box 424, London, SW3 5DY, UK. (Fax: 44+171 351 4848); e-mail: irdial@irdialsys.win-uk.net. Online Update Improvements continue on the Longwave Home Page (see top of this column for URL). By the time you get this issue, the file libraries should have some additions, as well as there being more news sections. Individual departments on the page are growing, and more folks are contributing helpful material to make it all work. One advantage to electronic publishing is the ability to cheaply archive more material than you could hope to keep on hand in print form. Another advantage is the ability to let readers link to other sites that can give them in-depth coverage of material. Right now, the links on our page let you learn more about red sprites and blue jets, cave radio, earthquake detection, and all kinds of topics with some relation to LF. (By the way, if you tried to search the Georgia Tech AirNav database before, you'll find it now works much better. It's still strictly U.S. aeronautical data, but it's very helpful...even includes airport mailing addresses.) A huge advantage of the Web is, of course, speed. If you were checking the Web page, you would have heard about the British ham band allocation almost a month before you received word in the mail. The same is true of the natural radio CD announcement on the Web last month, which is only now appearing in print. I'd like to convert one of our entire past editions into hypertext format, as a sample issue for prospective members who discover us on the Web. I hope all our columnists and authors will be agreeable to using one of the issues from late last year or early this year, and I'll be in touch with more of you as we get closer to that point. (But don't worry. We're not about to do like some magazines and convert to only publishing online. For one thing, that takes way too much work!) The Longwave BBS (706-672-0360) continues to grow, too. This month we added several MPEG movie files of sprites and other lightning phenomena, and a neat MPEG viewer for Windows that even works on my older PC! The MPEG files are also available directly from NASA, through the Longwave Home Page. They include some of the Space Shuttle lightning videos you may have seen on the PBS program Savage Skies...which I hope will be repeated some time this summer. BPSK Update Cliff Buttschardt (HDO, W6HDO) announces that version 4.5 of Bill de Carle's COHERENT software is now available, and that it "is really a good one, fixing some problems. Better yet, included are some text files which further describe BPSK and CCW principles. Much of this is a repeat but now updated and good reading for all." Version 4.5 is available on Bill's BBS, his Web page, our Web page, and the Longwave BBS. And it's free. So you have no excuse not to download it! Not all LF work "out West" is BPSK or CCW. "Just an hour ago, the West coast had another fine 1750 meter CW roundtable. Bill Lake in Santa Barbara is getting used to RST 599 signals now! My biggest problem is the power line carriers which mask signals that I could work. Saratoga and San Jose were present as was PLI in Burbank, CA although the PLC QRM was bad enough to make a QSO difficult! We all will be on 1844 tonight to again duplicate effort on BPSK and CCW primarily. Of course CW and SSB can be used if advantageous. That is the reason for picking such a frequency in addition to the fact that the oscillator in the Sigma Delta board occasionally leaks into the 160M receiver. This signal 800 hertz away causes no problem as the synthesized local oscillator is there anyway! Join us on 1844 if you can." The HDO(nul) beacon uses a section of old broadcast tower (a heavy-duty old tower, about 24" on each face). And despite what you may have heard, it does sometimes rain in sunny California, and lightning protection is an issue. The HDO beacon uses a unique protection technique. "The entire affair is built on an 0.090 inch thick aluminum plate as a ground plane, and enclosed in a Tupperware container. There is a two inch broad copper strap and a large copper ring to which the 100 plus radials are connected. A BNC connector with four stout screws elevate the connector above the ground plane such that the gap formed is less than a millimeter. Three components, a NE2 bulb, 10K resistor and a 30 volt zener are placed to ground. The transmitter is connected to this point via a ten microhenry choke to the FET final The FET is rated at 100 volts breakdown. Since the zener does not have hole storage delay, it should operate fast enough to save the FET and sacrifice itself. So far, no problems with lightning even though a 160 meter antenna at the same site has flashed over during a storm." Way-Out Stuff A few quick notes from space... -The Summer Solstice has just passed, and so, perhaps, has the solar minimum. Sky & Telescope magazine reports that solar researcher Patrick McIntosh thinks we may have reached the precise minimum between sunspot cycles 22 and 23 a few weeks ago. Solar flux at 10.7 cm has apparently bottomed out, and there's reportedly evidence of more active regions on the Sun. -You probably heard about the failure of the new Ariane 5 rocket on June 4th. You may not have realized that the payload related to VLF and natural radio. Four identical satellites, a group known as Cluster, were to study the electromagnetic environment around Earth, including interactions of charged particles with the magnetic field. Ten years of work (mostly by the ESA, with some US participation) and $400 million went up in flames. Being the first launch, there was no insurance. -The American Astronomical Society held its summer meeting at the University of Wisconsin in Madison last month. Among the record number of papers were to be some on new findings about interstellar clouds in the vicinity of our solar system, studies of the Sun by the ESA-NASA Solar and Heliospheric Observatory (SOHO), and the aptly-named Global Oscillations Network Group (GONG). Some of these--especially the latter--could be of interest. We'll try to find out more. On To The Mailbag... -Welcome back to Fred Lord (3GOATS; 11383 Wagner Creek, Talent, OR 97540), whose beacon is on the air 24 hours a day at 186.1 kHz. Fred reports he has "been recording many nice whistlers at this location. I am looking for someone to simultaneously record whistlers and WWV time marks, about 300 miles from this location, to produce a stereo whistler recording." If you're about that distance from Fred, and would like to participate, you can write him at the above address, or call him at 503-535-4074. -John Lyman (TAL; Tacoma, WA; e-mail: Jlyman@wport.com) reports a change in his e-mail address. It was formerly handled by Prodigy, as was his World Wide Web page. "My web site on the Prodigy server is now deleted, I will e-mail you with the new URL on the WorldPort server when it is up. Expect that to be about a month or less." The e-mail change is effective immediately. -Bill Thomas (AL, KC9AL, St. Louis, MO; e-mail: s945527@umslvma.umsl.edu) reports LowFER AL never made it on the air last season. But there's a good reason. "I have been busy working on my Master's degree which I just completed this past May. I'll have more time to devote to LF this coming fall and winter. I have built a new transmitter and am anxious to get it on the air." Bill adds that he appreciates the Longwave Home Page. -Ed Dahlgren (ed@satcom.whit.org) viewed the Web page, and checked in to the BBS this past month. "I figure I've been interested in ham radio about 30 years, but I still don't have a ham license. (Maybe Mom and Dad should've let me mail-order that Novice kit way back when, huh?) And is it possible I remember reading about 1750 roughly 15 years ago in a column in The Mother Earth News? I think so...the 1 Watt/15 meter limitations sure sound familiar. Anyway, I sent LWCA a check today, and I'm looking forward to reading your future columns as well as the previous ones I'll download in the evenings." Glad to have you on board, Ed. And I wouldn't be at all surprised about LF in Mother Earth News. As I recall, Copthorne MacDonald (please forgive the likely spelling errors) covered just about every radio-related topic in his columns. -Bruce Koehler (YB, BK, AA0YB; e-mail: aa0yb@juno.com) tested the new free--well, advertiser-sponsored--E-mail service called Juno, that his dad Lyle told him about. The first message arrive too late to get in last month's issue. At that time, repairs to YB were underway but BK was running. "Getting YB back on has been slow. One day when I was outside wrestling with ropes to get the remains of the YB antenna out of the cottonwood tree, a ham neighbor (Gary, WA0BWE) came by. He said that when YB was running, he was hearing it every 179KHz up into the 2 meter band! I have been reluctant to put it back on the air. I built a low pass filter and we checked it out at Lyle's place during the Easter weekend. It seemed to be working fine. I'm in the process of building a new exciter and enclosing the whole works in an aluminum box, including the low pass filter. When I get that done, I'll think about hauling a new antenna up into the tree." "Jean and I went to Florida for a week in mid-April, and I brought along a universal preamp along with a Radio Shack DX390 and a 25 foot long piece of wire. We stayed on the Gulf side near Ft. Myers and Naples. I tried on a couple of mornings to hear some FL and GA LowFERs, but heard nothing but airport beacons. I didn't hear much power line noise on the beach, and static levels were fairly low, so I must have been too far away or most of the beacons were off the air. Back home with the same setup, I can hear both LEK and BK easily at about 100 miles away." "I still hear LEK regularly and faintly hear SAM both in Maplewood MN and Shell Lake, WI. I can sometimes hear 0KVL, which seems to still have an intermittent transmitter problem. RM comes in well at Shell Lake, and he's been on quite a bit this winter and spring. ART has a fairly good signal too, often with an interesting message when he turns his beacon on about two days each month. OK has been the last DX holdout, Both Lyle and I have heard him sometimes in the early mornings this spring." "Last summer, BK was on mostly on weekends when I was at the cabin, but off during the week. I'm going to try to keep BK on all summer, and replace final amplifier components when they get zapped. I have been thinking for some time now about building a lightning detector circuit that grounds the antenna and turns off the transmitter for several minutes after a strong discharge is detected. Shell Lake is very high this year after the big snow melt, and half of the ground radial system is under water. We're considering raising the cabin a few feet and filling around it." But just a couple of days later came word that "we had a big storm at Shell Lake that took the BK antenna down. The top hat was pretty severely twisted, but I think I can salvage most of it. In that storm Saturday night 5-18-96, we also got dumped on with 4 inches of rain, so now the lake level is REALLY high! It will take another 10 inches to put the cabin floor joists in water though. However, the shed in which the BK transmitter is housed sits on 4X4 skids, and they're sitting in water now. I don't know when I'll get BK back on the air, perhaps on Father's Day when dad visits me, he'll be willing to help hoist the antenna back up. If we raise the cabin and shed to get out of water, the top of my antenna will go higher too. All the more incentive to do it!" -Lyle Koehler (LEK; Aitkin, MN; e-mail: lek@juno.com) reports, "On the local LowFER scene, we win some and lose some. SAM has rebuilt his antenna and seems stronger than ever. RM has been running continuously; I'm hoping he will stay on all summer. ART is still available by request." "I just heard from Tom Lambert that his 0KVL beacon is off the air. He had to remove the trees that supported the top hat in order to put in a new drainage field for his septic system. I guess it's a matter of priorities -- HI. With luck he may get a new LF antenna system installed before next winter." "LEK has been left running during a couple of thunderstorms this season without a disaster. I recently put a shunt inductor of about 50 microhenries between the base of the antenna and ground. This transforms the feed impedance from its nominal 15 ohms up to 50 ohms, where my transmitter achieves its best efficiency. I'm hoping that the shunt inductor will also improve the transmitter's chances of survival during thunderstorms. But when the sparks are really flying, I still throw the switch that shuts off the transmitter and grounds the antenna through a relay." Lyle is considering an article on the technique for a future issue; should be interesting. "Regarding the 'Efficient High Capacity E-Field Buried Antenna for the Medfer Band' in the June LOWDOWN: Readers who don't wish to build their own may contact the HeliMax corporation for a commercial version. See the HeliMax ad on page 191 of the April 1996 QST." -John T. Collins (P, KN1H; John_T_Collins@vtetv.org) advises, "P is now back on the air nights and weekends and much improved. It now is a 45' aluminum mast matched by 2.4MH coil. I basket-wound the coil using Bill Bowers' info as a guide and it ended up being 24" diameter, 10" long of #10 solid copper wire. Q seems to be about 400. I used a PNP rf transistor tapped low on the coil for the final, which ensures that the antenna and coil are always at DC ground. Hopefully, this will encourage a longer life during near-by thunderstorms!" Footnotes. I may not have a chance to write very much myself next month, so be sure to send your news and views. Try to stay cool. 73. - - -