THE LF NOTEBOOK #27 The Mailbag, News and Comments About LF Radio & Other Experimental Topics From the June, 1995, LOWDOWN John H. Davis, PO Box 367, Warm Springs, GA 31830 -Fax: (706) 672-0964 -E-mail: johnhdavis@aol.com -Longwave/Part 15 BBS: 706/672-0360 (thru July 15) What is so rare as a day in June? Other than any meat grilled outdoors by my brother in law, I mean.... Usually, correspondence starts to get rare about this time of year, but it held up pretty well this month, and most of our news is actually in the Mailbag section. Just a few brief notes, then, and we'll proceed there. An apology. These continuing brief power outages scramble the answering machine's message count, and I fear I may have missed some messages. For dependable messaging, you should probably use the fax and/or the BBS for now. Another apology. The digital signal processing series will probably start next month, instead of this time. Announcing a contest. I'm about to run out of ways to announce that I'm having to postpone something for which I've previously built up expectations. So, I believe we need a contest to see who can come up with the most original ways for me to postpone things. I'll be working up some contest rules...eventually.... LF Ham Band. In recent weeks, there has been some grumbling around various computer forums to the effect that the ARRL and FCC haven't been doing anything toward a longwave amateur band allocation. In point of fact, they have been going through the necessary procedures, though it's not a very high priority issue. The NTIA, which is increasingly involved in allocation issues, has been at work on this matter in connection with an overall study of spectrum requirements for licensed services. Their report, issued in April, endorses the idea of a ham band at 160 - 190 kHz. For more on this, see the letter from Malcolm Keown in the Mailbag section. Book Report. This column doesn't usually include book reviews, but I thought I'd mention having received James McCallie's Low Frequency Radio and Lightning Detector Projects that was offered in his article last month. It's a very nicely printed book full of interesting project ideas, some of which you might use right from the page, and some that may inspire variations and adaptations of your own. For my part, I always enjoy a book that stimulates my imagination in this way and contains such pleasant surprises. Not all of the projects are represented as being ultimate performance examples, using, as they sometimes do, parts such as the 741 op amp, or the most basic diode or BJT frequency mixers. A little more complexity, in some cases, would yield more performance. But the beauty of the designs I've tested so far is that they extract better performance from the devices and configurations than one would suspect, and the minimum-parts-count philosophy should enhance reliability. Would you have thought Radio Shack transformers could be used as chokes or to couple signals well up into LF? I wouldn't have suspected it before. The patented lightning sensor circuits are truly remarkable. There's an interesting section on ultrasound, a summary of LF transmissions and phenomena, a list of reference works, a suppliers' list, and photos of the 1LWLF beacon installation, in addition to the projects. All in all, I think, a very worthwhile addition to the experimenter's library. BBS Success. The GRAM spectrogram program, mentioned in last month's issue, has turned out to be the most popular file ever placed on the Longwave/Part 15 bulletin board system. We even received a request for the file from Germany! People checking in for that one file generally found others they wanted, too, making this the busiest month yet for the BBS. Usage peaked around the weekend of May 13 - 14, when we had as many visitors as we have in an average month. That's what it's there for, so feel free! The BBS hours are now "summer schedule," meaning all weekend, plus all weekdays except some afternoon interruptions. The best way to use the file library is to look at the log-on news bulletin for the date of the latest ALLFILES.TXT. If it's a later version than the one you have, download it, log off, and view it in any convenient editor that can handle 40K+ ASCII files. Make a list of files that interest you, then log on again and download the ones you want. Using an "allfiles" file saves a lot of connect time when browsing through the library, and provides more information than the basic list this BBS software is able to furnish. There's a zipped version, too, to save even more time. Another neat file was uploaded this month by David Oliver (see his letter, below). It's named mfj-259.zip, contains Windows Write text and PCX images, and can be used by anyone with Windowstm. By the time you read this, I should also have a semi-generic version with plain text and GIF images. No modem, slow modem, bad phone lines? I'll be glad to copy any of the BBS files onto floppy for you under the same terms as for the GRAM program last month: Send a blank diskette, either 5.25" or 3.5", PC-formatted for 720k, 1.2M, or 1.44M, as applicable; plus a sturdy, self-addressed mailer and return postage. If the mailer and stamps are impractical, a small donation can be substituted. (Don't send over $3 in any case. Some software has limits on how much can be accepted for distribution costs.) No computer at all? Well, I can't help you with running programs, then, but any non-copyrighted text files can be printed out and sent to you. (Modest donation accepted for this service, depending on file length.) Also, some of the folks who appear in the Mailbag give only their e-mail addresses or BBS name. How can you communicate with them if you don't compute? Easy. Write or fax your message--relating to LF/MF topics only, please--to them in care of this column, and I'll be glad to forward it electronically. No charge. On To The Mailbag... - David Oliver (WB6VKH) notes a surprisingly good response to his offer of information to modify the MFJ-259 antenna analyzer to work down to 100 kHz. "I must have received about 35 letters asking for the MFJ-259 mod {as of mid-April--Ed.}; it surely caught me a little flat footed. About 10 were from outside the US." The strong response prompted David to upload a file (actually, a group of text and picture files) describing the modification, to the Longwave BBS. They are so well done, I've asked if he'll let us use them as an article in the Lowdown too. David adds: "There are some articles (short but good) about VLF in past publications. One is a "Grid Dip Converter To 100khz" in Ham Radio (HR), August 1979. Another is "Long Wave Simplified" about a passive converter for your HF rig which will get you down to VLF. CQ, March 1976." - Malcolm P. Keown (14 Lake Circle, Vicksburg MS 39180) passed along word from The ARRL Letter last month, roughly about the time word came across the on-line services, that the National Telecommunications and Information Administration (NTIA) cites the possibility of allocating an additional 2,180 kHz of spectrum for amateur radio use, including the existing 1750-meter Part 15 band. It's not a "done deal," because, as the NTIA report notes: "Amateur requests for international reallocations would be appropriate issues for ... future World Radiocommunication Conferences (WRCs). Additional allocations at 160-190 kHz, and near 5 MHz will require technical studies to determine the availability of these bands to support amateur use." The study has been underway for three or four years, and is intended to estimate spectrum needs for the next 10 years. The ARRL says it responded to the NTIA Notice of Inquiry in June, 1992. Not all of the spectrum requests were evaluated favorably. Co-primary status on 70 cm is out, and prospects for 902 MHz aren't very good. Some of the HF bands were endorsed subject to decreased use by aeronautical mobile and international fixed services. In case you haven't seen the list yet, these are the slots mentioned favorably in the report: 160 to 190 kHz (30 kHz); near 5 MHz (50 kHz); expansion of 10 MHz band (200 kHz); expansion of 14 MHz band (50 kHz); expansion of 18 MHz band (150 kHz); expansion of 24 MHz band (150 kHz); 30 to 50 MHz, 5 slots of 50 kHz each (250 kHz total); 219 to 220 MHz (already in process); satellite downlink, 29.7 to 30.0 MHz (300 kHz). - Jim Mandeville (e-mail: jmandevill@aol.com) and family are once again stateside. "We have left Saudi Arabia and are settling here in Tucson, AZ. Not much LF activity here, apparently, but maybe I can remedy that to some extent, although antenna restrictions are rife in the near-town area I need for ready commuting. I heard the western Lowfer net on 75 ssb Thursday recently. Sigs were R4-5 but rather weak here with my makeshift antenna (we're still in an apartment complex while house hunting). I expect to be on HF in a few months and will use it for communications from remote whistler locations!" - Don Burns (e-mail: epur01@email.mot.com) works for Motorola's North American Radio Systems Division in Plantation, FL, and says, "I am a newcomer to the Lowdown and VLF in general and am located in the Fort Lauderdale area. I am looking at your column in the April issue and have a couple of questions for you: "1 - Your beacon list has a column on it called GRID. Is this a location reference from a map? If yes, what map?" It's been a while since we mentioned the grid system, so it may be worthwhile to briefly explain it for benefit of our newer members. Grid entries in the beacon list are the four-character version of the Maidenhead grid locator system used for contest purposes in amateur radio. There is usually a U.S. map of this grid system in the ARRL Handbook, and I believe the ARRL also sells full size maps of the U.S. and worldwide Maidenhead grid system (225 Main St., Newington, CT 06111). The two capital letters at the beginning of the grid designator locate a quasi-rectangular block ("field") on the surface of the globe, enclosing 20 degrees of longitude and 10 degrees of latitude. Those rectangles are broken down into smaller blocks ("squares"), measuring 2 degrees longitude by 1 degree of latitude, and denoted by the two digit number. The first capital letter is determined by how far east of the 180 deg. meridian the site is. Most of the contiguous United States have D, E, or F as the first letter, going from west to east. The second capital letter is apparently determined by how far north one is from the South Pole. The southern half of the "lower 48" is in the M strip, and the northern half is mainly in the N strip. The tens digit of the number increases with eastward position in each field, and the units digit increases with northward position in the field. In the full implementation of the grid reference, there are two more lower-case letters that divide each of these numerically designated rectangles into extremely small sections of the earth's surface ("sub-squares"), measuring 5' x 2.5' of arc. It is possible to convert latitude and longitude information into the grid reference without a map. The easiest way is by computer, of course. There are programs for DOS and Windows that perform this task. You can find some of them on the Longwave BBS. Don also had a second question: "2 - Is there a Internet mail list that lowfers hang out on?" I am not aware of one exclusively for longwave, and in fact wasn't sure of any LF discussions other than those that sometimes take place in the ham radio sections of America Online and CompuServe. However, it turns out that there is some discussion of low frequency topics on at least one Internet Usenet group, as mentioned by Rick Robinson in his message, below. Don remarks, "Have been spending the past month doing a lot of LF listening in general and am surprised to find that I can consistently hear beacons in Cuba and Freeport, Bahamas, simply using a convertor with a 75A-4 and a 102 inch active whip." I believe he will particularly enjoy the reception next fall and winter in the quiet(er) QRN season. - Rick Robinson (KF4AR; Charlotte, NC; e-mail: rerobins@uncc.edu) checked into the BBS recently, and says "this is a great source of info for my tinkering in LW/MW DXing. Moved into this house last August and haven't had much time until now to experiment with antennas. I'm enjoying the Lowdown every month and will be logging in here from time to time. I also rec the rec.radio.shortwave and boatanchor, Sony 2010 and Drake R8 lists on Internet. I've met quite a few LW/MW folks there." - Dr. Murray M. Lewis (VK3EZM, School of Human Biosciences, LaTrobe University, Australia 3053; e-mail: hubmml@lure.latrobe.edu.au) recently received a sample of the Lowdown from Bill Oliver, and expresses an interest in "phone operation, ssb, am, or fm on 1750 meters, and converters to front an Icom 735 ham HF rig -- or better still a transverter circuit for homebrew." Your columnist is sending word on a few sources and resources, but if you've got some suggestions for Murray, please pass them along directly, too. - Lyle Koehler (MIN, LEK; K0LR; Aitkin, MN) reports "Until today our daytime QRN levels have been fairly low. Low enough so that the messages that BK sends at 15 WPM can almost always be copied on the first pass. Today (May 7), however, the QRN level is too high to hear anything but NDB's." "LEK continues to operate full-time except during thunderstorms. BK is on a weekend-only schedule for the summer. SAM has been off for a couple of days. He may be back on right now but I can't detect him through the QRN. I haven't heard RM for several months, and 0KVL has not been readable on LF for about a month. 0KVL (MF) is still running, so I think the absence of 0KVL (LF) is a transmitter problem rather than an indication of a summer shutdown." "I'm still 'improving' my LF/MF preamp. It's getting hard to run any actual receiving tests because of QRN and the limited availability of LowFER signals. (NDB's are too strong for meaningful tests.)" "The GRAM program {the Windows-based audio spectrogram program mentioned last month} looks like it may offer some promise in finding weak signals in noise and interference. In some limited tests here, it hasn't been able to pick LowFER CW signals out of the noise as well as I can do by ear. However, it may help to pull out weak CW signals that are very close to strong PLCs. The other evening I was using GRAM to examine the sidebands from GLS in Texas and IIB in Iowa, both at about the same signal level and only a few Hz apart. There was another very strong carrier about 20 Hz higher. It was actually possible to read the dots and dashes from both GLS and IIB on the screen (but I cheated and used the sound from the speaker to tell where to look as the GRAM cursor slid along the display-HI)." Actually, that strikes your columnist as being what we in educational media (and folks in the advertising industry) try to do every day...reinforce messages by delivering them through more than one sense at a time. In trying this technique myself, I find a ringy filter to be a hindrance to the visual interpretation, possibly worse than for aural reception. In fact, if there's enough random background noise, you can develop a rough plot of your receiver's IF bandpass, or your external audio filter's characteristics. Where the program really shines, of course, is in analyzing natural radio signals, especially whistlers. - John Amery (KF0HX; Route 1 Box 38A, Elsberry, MO 63343) writes: "Just got my first (recent) Lowdown in the mail. Had interest in 1750 communication 10 years ago, but didn't make it on the air. Have been active on and off on 2 m FM and 3/4 m TV in the St. Louis area the past 10 years. My intentions are to put a BPSK signal on from about 50 mi North West of St. Louis. Would be interested in hearing from others using phase modulation TX and PLL receivers. Phone (314) 233-7554 workday, (314) 898-5770 evenings & week-end." John would like to communicate with fellow St. Louis area hams Bill Thomas and Stan Wilson by phone for planning and coordinating purposes. - Cecil Wadford reports he is getting settled in at his new QTH, but is setting up a workshop now, and wants to work on a BPSK receiver before putting the RED beacon back on. It is on a roomy 5-acre site now, although he didn't specify exactly where. He estimates he will be back on the air somewhere between the first and middle part of June. - Mike Kana (AA9IL) has been interested in longwave for a while, and recently checked in on the BBS. "I recently picked up a Watkins Johnson 340A VLF receiver. I was wondering if anyone else has experience with this set or the earlier CEI. It seems real sensitive and should work well once I put up an active antenna. I am about 45 miles north of Chicago and have the usual neighborhood noise problems. Time for a good loop! Anyway, look forward to posting some new found beacons." - Bart Prater (VA, N4ZV; Smith Mountain Lake/Moneta, VA) will be keeping both his LF and MF beacons on during the summer...at least, between storms! He reports "noise is up and receptions are down here. ABC is about all I'm hearing any more (mid-April). I'm sure, as in years past, Todd and I will be able to copy each other with some difficulty through the summer. Sunset seems best, since the noise builds later on." "I sure appreciated the reception reports in the April issue. Until then I had no idea anyone except Todd had copied my LF beacon. Special thanks to Brice for passing them along!" "A couple of junk box tips. I recently built a new crystal controlled exciter for my LF beacon using parts from a defunct 'electronic' -- DSU telephone. They're loaded with chips and transistors. By removing the case from one of the on-board crystals, I was able to carefully scrape it a bit with a knife blade and coax it up in frequency to produce a divide-by-32 output on 187.800 kHz. A good source of parts!" (Home-tweaked crystals surely hearken back to the good old days.--JHD) "Also, by swapping two crystals in a junked CB radio and adding a decade divider, I ended up with a nice 40 channel synthesizer that I'm sure will be handy for avoiding QRM in the MedFER band when the expansion begins." Footnotes. We'll be looking for your news and views for the July edition. Have a really great summer! - - - #(Special File Associated With This Month's Column:)# OP-AMP PROXIMITY DETECTOR by Rick Wright, R, KA5YWH *Download PROXIMIT.ZIP if you use PKZip and can view PCX images. *If you cannot use PKZip, then download PROXIM.TXT and either PROXIM.PCX or PROXIM.GIF as needed.