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Date: Mon, 19 Sep 94 08:30:53 PDT From: Info-Hams Mailing List and Newsgroup <info-hams@ucsd.edu> Errors-To: Info-Hams-Errors@UCSD.Edu Reply-To: Info-Hams@UCSD.Edu Precedence: Bulk Subject: Info-Hams Digest V94 #1039 To: Info-Hams Info-Hams Digest Mon, 19 Sep 94 Volume 94 : Issue 1039 Today's Topics: 2m handhelds ?? Embedding e-mail addresses Ham activity in Seatte/WA Help Kenwood TH79 Mod File r1.5 New Ham NEWSLINE VIA INTERNET VE Session Stamford,CT Send Replies or notes for publication to: <Info-Hams@UCSD.Edu> Send subscription requests to: <Info-Hams-REQUEST@UCSD.Edu> Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Info-Hams Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/info-hams". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: Sun, 18 Sep 1994 11:53:41 GMT From: elroy.jpl.nasa.gov!grian!morris@ames.arpa Subject: 2m handhelds ?? To: info-hams@ucsd.edu phillips@eso.mc.xerox.COM (Mark Phillips x75493 - ESO) writes: >(unknown poster a new Technician Plus). >What do y'all recommend? >Icom IC-T21A, Icom IC-2GXAT, or the Kenwood TH-22AT ? >Cetainly don't overlook the Yeasu single and dual band HT's. Yeasu >offers a lot of radio for usually less money than Icom or Kenwood. >Try before you buy.... check the "user interface" commands on some >radios to decide which one is the most logical to use. You don't want >an HT that requires you carry an instruction manual. Definitely try before you buy. The Icom IC-02/03/04 were famous for the b.s. it took to go from repeat to simplex on the same channel. Many people just sacrificed another memory position. The early ones forced you intothe same PL tone for memories 1-8, 9 and 10 had different tones. A new CPU chip fixed that bug, but at extra $$$. The Yaesu 709 of the same era had an offset switch for -, spx, + which was it's major comparison feature. The Icom had the easy-on battery, where the Yaesu had a battery door in the back of the case, and a cartridge battery. And when you look at a radio's price, figure in from the start two full size batteries (the original one will be a small one, that will end up being a end-of-the-day spare), and a drop-in charger. Your next purchase should be a leather case or holster. Later on you will want a speaker-mic (MFJ has some nice rugged ones - check QST or 73), a mag mount antenna and a mobile power cord. >Everything else being the same, you might also consider a single band HT >to simply "get your feet wet" before you spend a bunch of money and >decide ham radio is not for you. It's easy to trade radios without >losing much of your investment. Attend some local radio club meetings >and ask the folks what radios they're using. (then if you have questions >you can get direct help) >One more thing... if you buy a used HT, expect the nicads to have >"memory failure" and therefore need replacing, adding to your cost. >=Mark= n2rpz@amsat.org That is one advantage of the older Icom IC-2, IC-3, IC-4, IC-02, IC03 and IC-04 series, as well as the Radio Shack 2m, 440 and real-soon-now-available duobanders. The battery packs are rather cheap and easy to replace - just unscrew the side of the case, and replace the battery cells for $30 or so... The Yaesus 727 packs (FNB-4s) that I use are almost as easy - just drop them once or twice and they split open :-). Change the packs, and tape them shut witha piece of clear 2" wide strapping tape. I put a piece of paper under the tape with a PL tone chart, my phone number, and a "Property of... Reward for intact return" line across the bottom. And if you are just geting started don't overlook a used radio from someone that is upgrading to a more-features radio, a newer radio, or lost interest in VHF/UHF. The ones to watch out for are the ones where someone went into it to fix it and "fixed" the wrong area... I lucked out - I picked up my Yaesu 727 duobander radio from someone who was a 20m CW addict and bought a duobander to chat with his buddies on a 440 repeater, and to have 2m for public service funtions - parades, etc. He found VHF/UHF wasn't his cup of tea. I picked it up used for overhauling a IBM AT that was suffering from a bad case of too many limited knowledge people trying to fix it and a little cash. I used it for a year, then sent it back to Yaesu and got a new main crystal (the radio was 1.5kc off frequency), a new metal frame inside and a new outer plastic case (I had dropped it once too often), new volume and squelch controls (noisy and stiff), a new lithium cell, new keyboard and a new mic & speaker. Plus a full tuneup and warranty. Its after 1am and I'm forgetting something else I had them do. Anyway, all of the above was about $225. So for under $325 I had a very good duobander that looks brand new, works like new, with a factory warranty. I bought a speaker-mic at a hamvention, and a cheapie case. I plan on having a local SCA leatherworker make me a custom leather holster. If you buy a used radio, you can also expect to replace the lithium cell - if there is one. You wouldn't want the radio to lose it's mind a month after you bought it would you? Mine did. Some clip in, some solder in. Some are easy if you have a steady hand, a good solder station, a vise to hold the radio, a third hand to hold a 6" magnifying glass and a lot of patienc a lot of patience. Some you need to have replaced by the trained people... PS - If I was going to find a decent duobander all over again I would have found me an Icom IC-32 - even if it took 3 months. That was a short-lived Icom duobander that was built in the shape of the IC-02/03/04 series. The main reason for picking that radio? Cheap batteries (the major repeating expense), 12 volt operation in a car without a bulky 9v adapter, decent speaker volume, aftermarket add-ons are easy to find (everybody makes them for Icom), etc. And ruggedness. My Yaesu has been the most fragile radio I have had. I understand that the IC-02 was the RS 2m model, and the IC-32 was the model of the soon-to-be-released Radio Shack duobander. -- Mike Morris WA6ILQ | All opinions must be my own since nobody pays PO Box 1130 | me enough to be their mouthpiece... Arcadia, CA. 91077 | ICBM: 34.12N, 118.02W | Reply to: morris@grian.cps.altadena.ca.us ------------------------------ Date: 18 Sep 1994 10:21:40 -0700 From: sdd.hp.com!math.ohio-state.edu!howland.reston.ans.net!usc!elroy.jpl.nasa.gov!netline-fddi.jpl.nasa.gov!nntp-server.caltech.edu!news.cerf.net!ccnet.com!ccnet.com!not-for-mail@ihnp4.ucsd.edu Subject: Embedding e-mail addresses To: info-hams@ucsd.edu Gary Thorburn/UB Networks (Gary_Thorburn/UB_Networks@UB.COM) wrote: : Considering the level of thought many posters put into their comments, : perhaps anonymity is a blessing. But if you have something to say : and you want all to know who posted it, or if you want a response : from as wide a community as possible, you must consider : that the real audience is much larger than those who will see your : posting today using a newsreader. The regular posting of Hams on Usenet to rec.radio.info is a good source of the current information you seek. You can easily search these files for New adresses for those hams that move up to new jobs. A lot of good effort goes into maintaining these lists. Check it out, they are probably on the same CDs you are reading. Bob -- Bob Wilkins work bwilkins@cave.org Berkeley, California home rwilkins@ccnet.com 94701-0710 play n6fri@n6eeg.#nocal.ca.usa.noam ------------------------------ Date: 19 Sep 94 13:53:31 GMT From: news-mail-gateway@ucsd.edu Subject: Ham activity in Seatte/WA To: info-hams@ucsd.edu Hi all, could someone please tell me of any club meeting, workshops or any other ham activity in the Seattle/WA area? Also directions for shops,flea markets etc. is appreciated. 73, Marco P.s. Reply via email -- Marco Fassiotto, i1iiy/aa1iu Internet : fax@sparc4.ico.olivetti.com AX25 : aa1iu@n0ary.#nocal.ca.usa.na ------------------------------ Date: Sun, 18 Sep 1994 17:08:47 -0400 From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!europa.eng.gtefsd.com!fs7.ece.cmu.edu!casaba.srv.cs.cmu.edu!bb3.andrew.cmu.edu!andrew.cmu.edu!cs6q+@network.ucsd.edu Subject: Help To: info-hams@ucsd.edu Hello I am in quite a Jam. I am looking for the postal adresses of all mail order companies dealing in communication equipment/ microphones, receivers, and transmitters. Also on the detection of microphones, receivers, and transmitters. Any information of any companies would be great. Thank you Marc Madjaric - Infojunkie - Forum - Pittsburgh PA cs6q@andrew.cmu.edu ------------------------------ Date: Tue, 13 Sep 1994 21:11:33 GMT From: darwin.sura.net!news.duc.auburn.edu!mallard!wagarbc@seismo.css.gov Subject: Kenwood TH79 Mod File r1.5 To: info-hams@ucsd.edu Kenwood TH79 Dual Bander Modification and Feature Guide r1.5 9/13/94 ======================================================================= Clayton Wagar, KD4IDN 920 West Crawford Street #7 Dalton, GA 30720 Here is a compiled list of modifications and features I've found for the Kenwood TH79 Dual Band HT. Thanks to the following for their contributions to this document: Mike Musick, N0QBF Cole Cunningham, AA7RD Duane Voth, KC5BGV Chuck Scott, N8DNX Having had many other radios in the past, and certain to have many in the future, I understand the anticipation of Amateur Radio operators to find modifications to their equipment. I started this document because I want to see _quality_ information circulated as quickly as possible, in order to save a lot of time and effort for others. If you have any other comments, mods, or information you would like to see included in this document in the future, please send them to: Clayton Wagar KD4IDN yensid1@aol.com Outstanding questions at the time this document was released: * Rumor of a keypad modification to the radio for "Wide band" TX, RX. If you know of this mod, please write to me, even if you wish it not to be published. This would save a number of poor radios from useless torture! Hope you find all of this information useful. Again, please send corrections or additions to yensid1@aol.com 73 de Clayton KD4IDN +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Contents of This Document +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ I. Disclaimer and other foolery II. Brief Description of the Kenwood TH79A Dual Band Handheld Radio III. MARS/CAP Modification IV. Extended TX/RX Modification ('Beyond MARS') V. Remote Base Operation VI. Post Modification Specification Chart VII. Cross Band Repeat VIII. Other Stuff +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ I. Disclaimer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Well, don't you get sick of this stuff? I know, I know. However, I must say that I cannot and will not be responsible for anything that might happen to your radio, your person, your dog, or other operators you might talk to with your th79. In addition, if you decide that, with your newly modified HT, you just absolutely must cause unlawful interference with another ham or another radio service, I won't pay your NAL. Really. Oh, and while we're at it... The extended RX/TX modifications may require you to solder or desolder really, really small components. If you want to know how small, look at the tip of an average ball point pen. Smaller than that. It takes about 1/2 of a second to wipe out several components as well as fry the board inside the 79. Please be careful. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ II. TH79 Description and Impressions, by Mike Musick, N0QBF +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Lulled by the sexy small size, I succumbed (or, rather, the credit card succumbed) and bought a Kenwood TH-79 dual-band H-T recently. Already owning a TH-78, the comparison comes easy. SPECS. The TH-79A is a U.S.-spec dual-band transceiver, featuring coverage from 144-148 and 438-450 MHz. Receive coverage is extended on the 2M side from 118 to 174 MHz with AM in the aircraft band; there is no extended UHF coverage without modification. Max power is rated 5W on VHF and 3.5W on UHF with a 12V source; max power with stock 600 mAH nicad pack is 2.5/2.0. There are three power levels for each band - high, low, and extra-low (30mW). There are 80 memory channels, with no evident expansion capability. U.S./Canada version comes with the CTCSS encode/decode option. Going price at a 7/17/94 hamfest was $480. GENERAL IMPRESSIONS. Tiny, tiny, tiny. Imagine putting a small duckie on the ARRL Repeater Directory - except that the 79 is narrower by about an inch. With the standard battery and not counting the belt clip, the dimensions are roughly 2" wide, 5" tall, and 1" thick. The belt clip adds 3/8" to the thickness; I left it off so it would be pocketable, and, frankly, it fits moderately comfortably in my work slacks' front pockets, which was surprising. It's tiny! (Oh, I said that already.) The 79's keyboard has larger buttons than it's predecessor (lacks the cover, too) which are much easier to use. Control layout in general is better and even in just a couple of days I appreciated the change. No more ambiguous power switch - it's in the primary band volume knob in a normal OFF/ON/VOL setup. Secondary band volume control is on the "ring" of the freq/channel encoder knob in a coaxial arrangement. There are no squelch knobs; it a key+knob function for both bands. Squelch control was, well, interesting. There are only six "settings", with usually only the lowest setting opening the squelch under no signal. Reading between the lines in the manual, apparently the squelch circuit is semi-automatic. I expected some limitations, but had no complaints under actual use - it worked well. With my expected habit of putting it in my pocket, I like the control lock switch - it's *not* an F-key function, but, rather is a slide switch next to the PTT. No more fumbling around to unlock it. Unfortunately, the lock function does not lock PTT - that has to be disabled with the "Tx Stop" menu setting. I found this out the hard way by putting it in my pocket and inadvertently keying-up a repeater. The 79 has an alphanumeric display capability of two lines of 10 characters, which is used in several ways. First, there is a "guide" facility, which provides online instruction for most operation features with a scrolling display. Then there is a "menu" function, which provides access to the settings which were normally done with obscure F-key commands in the 78. Setting the various functions is very clear this way. There is also a status review mode, where the more important settings are displayed. Finally, the alphanumeric display can be set for each programmed channel. Seven characters positions are available, and almost the entire extended ANSI character set - that's right: lower case, symbols, and accented characters - can be used. However, alpha display is mutually exclusive with frequency display. Frequency display mode can be selected in case you forgot what was "underneath" your programmed channel ID. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ III. MARS/CAP Modification provided by Mike Musick, N0QBF +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Here is the MARS/CAP modification for the new Kenwood TH-79A dual-band HT. Usual disclaimers about doing mods apply. 1. Remove battery. 2. Open case by first removing 3 screws (#00 Phillips) on back and 1 screw on side hidden underneath the rubber flap covering the DC power jack. Gently pry apart starting at top; BNC connector will move with back, knobs with front. 3. Spread unit out. Wires will "hinge" on the side with the PTT button. 4. Looking on the back of the keypad (front) half, locate green wire on upper left, just below the CTCSS decoder module. 5. Neatly cut this green wire, and tuck back in so ends won't touch each other or other components. 6. Reassemble. Programmed memory will be lost since the CPU will notice the strap change and reset itself. End result - Before: VHF RX - 118.000-173.995 TX - 144.000-147.995 UHF RX - 438.000-449.995 TX - 438.000-449.995 After: VHF RX - 118.000-173.995 TX - 142.000-151.995 UHF RX - 420.000-449.995 TX - 420.000-449.995 Automatic repeater offset and shift selections remain normal. And this tip comes from Duane Voth, KC5BGV... "The MARS/CAP mod can be made without opening the entire case up. You can fairly easily cut the green wire by simply (and carefully) removing the CTCSS decoder cover and using a small pair of diagonal wire cutters." +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ IV. "Wide Band" Modification, provided by Cole Cunningham, AA7RD +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Following is a modification for the Kenwood TH-79A Dual Band HT which opens it up to tuning from 67-174 MHz and 400-511 MHz. Actual receive was 85-135.995 AM and 136-179.995 FM with reasonable (0.5 microvolt or better) sensitivity at all the points I measured. Transmit was 136-179.995 and 400-511 with power dropping off at the ends but still usable (about 0.5w on the high scale at the band edges). As usual, I take no responsibility for the mods, or your use of the unit after mod. Please exercise good judgement and don't endanger our ham bands with your irresponsible actions. The observations noted are all I tried and I have no further data. This is such a delicate operation that one shot was all I wanted to do, and when it worked I quit!!! WARNING-CAUTION-LOOKOUT-ETC!!! The diodes to be moved are microscopic!! About 1mm long by 0.5mm wide. This mod should be done by professionals on a closed track only. Children, do not attempt this at home. Requires extremely small soldering tools and MUCH skill. I had a professional surface mount facility do mine... 1. Open the unit by removing three screws from the back and one under the DC power input cover. Carefully separate the front and back pieces. The two case halves may be disconnected by pulling the wired plug and by prying the brown latch on the ribbon cable connector up enough to release it. 2. On the front PC board in the lower right corner as viewed from the rear with the knobs pointing up there are seven spots for diodes in a row, with one diode missing. | o o o o x o o | ________________| 2 3 4 5 6 7 8 The numbers are D302-D308, left to right, with D306 missing. 3. Remove D304, and D307. Put them away in a safe place (Just in case...)_ 4. You should now have: | o o x o x x o | ________________| 2 3 4 5 6 7 8 5. Reassemble and good Luck. Enjoy, but don't create problems with the new capability...Wouldn't it be nice if Kenwood would make a RX only mod with these capabilities and we wouldn't have to worry about accidental transmissions where we shouldn't be transmitting. I, for one, don't want or need to TX, just RX... 73, Cole, AA7RD August 11, 1994 (Note - This mod also adds 2 more menu settings. One of which is an AM/FM demod selector for the 300-400 Mhz band. To access this band, select the VHF band, press F, then press the Low/Hi key. Repeat to return to 144 Mhz. The AM/FM selector will allow you to listen to Military transmissions in the 300Mhz band in either AM or FM. - Clayton) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ V. Remote Base Operation with Kenwood 732/733 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Kenwood has now simplified remote base operation of their mobile rigs with the TH79. I will not give a step by step on how to control the mobile rigs, since they are different. Hoewever, to really understand this feature, I would first get to know the remote control feature on the mobile very well. This makes the following explanation a little clearer! To access this feature, hold [PTT] and [MR] while [POWER ON]. The display will indicate -RC-, which I presume means 'Remote Control'. If you have correctly matched your DTSS codes, frequencies, etc, the dual bander's keypad now becomes a function pad. Pressing certain keys enables or disables functions on the mobile rig by sending the DTMF sequences for you. Please note that all this fuction does is send the DTMF tones over the air to control your mobile rig. I have not made a list of what each key does, but as the 79 sends the DTMF tones, the display will indicate the function. (i.e. - RPT ON, RPT OFF, TONE ON, TONE OFF, etc.) 73 de Clayton KD4IDN And this from Chuck Scott, N8DNX... "The "RC" function is configured to directly control radios such as the TM-732. In fact, if you look at the layout of the microphone remote commands for the 732 it very closely matches the key assignments for of the "RC" mode. Since I have a TM-732 installed in my car, I had a chance to try this out and it's VERY convenient. Everything from direct frequency entry with the "F" key to enabling X-Band repeat. I'm really surprised they aren't marketing this feature of the radio." ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ VI. Post Modification Spec Sheet, by Clayton Wagar, KD4IDN ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Here is a small chart showing the measured specifictions of TH79 S/N 60300272 after modification. The measurements were made with an IFR 1200S Service Monitor, on the bench, with a 6V power supply. Your milage may vary - these are just what happened with mine, and I would suspect that most units are pretty similar. 73 de Clayton KD4IDN Band - VHF ----------------------------------------------------- Frequency Sens (uV) Power Mode --------- --------- ----- ---- 108 4 - A3 110 2 - " 115 .75 - " 120 .40 - " 125 .30 - " 130 .30 - " 135 .30 - " 140 .12 2.9 F3 145 .12 2.9 " 150 .13 2.8 " 155 .15 2.4 " 160 .18 1.9 " 165 .20 1.45 " 170 .21 1.10 " 175 .30 0.85 " 179.995 .35 0.70 " Band - VHF (2) (set to 300Mhz) -------------------------------- Frequency Sens (uV) Power Mode --------- --------- ----- ---- 300 50/75 - A3/F3 320 4/20 - " 340 .3/.6 - " 360 .2/.5 - " 380 .2/.6 - " 400 .2/.75 - " Band - UHF ----------------------------------------------------- Frequency Sens (uV) Power Mode --------- --------- ----- ---- 400 11 1.0 F3 410 4 1.5 " 420 1 1.85 " 430 .2 2.2 " 435 .12 2.3 " 440 .10 2.5 " 445 .10 2.5 " 450 .10 2.5 " 455 .15 2.3 " 460 .16 2.3 " 465 .20 2.0 " 470 .45 1.8 " 480 1 1.6 " 490 2 1.3 " 500 6 1.1 " 510 no RX over 509 0.8 " ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ VII. Cross Band Repeat, from Chuck Scott, N8DNX ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ The TH-79 does go into X-Band repeat. Press the "F" key then the "MONI" key to enter repeat mode. Use the same to return to normal. There is a 10 min transmit limit so it's not useable for long duration monitoring of a continuous transmission. That's understandable in light of the number of horror stories I've heard of people frying their HT's in repeat mode. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ VIII. Other Observations, Ramblings, Etc. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ Date: 18 Sep 1994 20:12:06 GMT From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!msuinfo!netnews.upenn.edu!netnews.CC.Lehigh.EDU!panda@network.ucsd.edu Subject: New Ham To: info-hams@ucsd.edu Hey all, I just passed my Technician exam - and now i want to learn code - I read abut a computer program available through the ARRL [I think it's called Morse Tutor] Anyone have any experience with it? Any reviews, recomendations, etc would be greatly appreciated... Also, anyone know of any upcoming hamfests in the South Jersey/NYC area? Thanx much.. 73, Joe --- ------------------------------------------------------------------------------- - Joseph Herman Thought is useless unless accompanied by action- - herman@yu1.yu.edu Action is useless unless preceeded by thought - a196@lehigh.edu Slammy@chop.isca.uiowa.edu ------------------------------------------------------------------------------- ------------------------------ Date: Sun, 18 Sep 1994 21:57:42 GMT From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!gatech!news-feed-1.peachnet.edu!news.duke.edu!eff!news.kei.com!yeshua.marcam.com!charnel.ecst.csuchico.edu!csusac!csus.edu!netcom.com!wa2ise@@. Subject: NEWSLINE VIA INTERNET To: info-hams@ucsd.edu Look in rec.radio.info and you'll see a transcription of Newsline into ASCII text. Usually shows up around Tuesdays. ------------------------------ Date: Sun, 18 Sep 1994 21:11:01 GMT From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!spool.mu.edu!howland.reston.ans.net!europa.eng.gtefsd.com!library.ucla.edu!csulb.edu!csus.edu!netcom.com!tja@network.ucsd.edu Subject: VE Session Stamford,CT To: info-hams@ucsd.edu The Stamford ARA will sponsor a VE session on Saturday, November 12, 1994. It will be held at 1PM at the Stamford Government Center 888 Washington Blvd. For more info contact Tom Alessi WB1L at +1.203.969.1880 -- --------------------------[ T.J. Alessi - WB1L ]----------------------------- T.J. Alessi & Associates * PO Box 16781 * Stamford, Connecitcut 06905-8781 Internet: TJA@Netcom.Com * MCI:Alessi@MCIMail.Com * Phone: +1(203)969-1880 ------------------------------ Date: 19 Sep 1994 07:58:47 -0600 From: mnemosyne.cs.du.edu!nyx10.cs.du.edu!not-for-mail@uunet.uu.net To: info-hams@ucsd.edu References <proctor-1409941724080001@mac-247-107.cern.ch>, <jas12-1509941522020001@131.111.200.3>, <jas12-1909941451290001@131.111.200.1>│▐ Subject : Re: Why is aviation COM VHF *amplitude* modulated? In article <jas12-1909941451290001@131.111.200.1>, Julian Scarfe <jas12@cus.cam.ac.uk> wrote: >Someone subsequently asked me *why* they are AM not FM (after all, >commercial broadcast VHF in the 88 to 10? MHz range is FM). Explanations >please? Money. It would cost billions of dollars to replace all the AM radios in the aircraft of the world with FM. Pilots would reject the idea because they would see no good in it. Another reason is the FM capture effect: While that's a Good Thing for most uses, it's a bug in the aviation arena, where both pilots and controllers need to know that a transmission was blocked, fully or partially, by another signal. -- Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can jmaynard@admin5.hsc.uth.tmc.edu | adequately be explained by stupidity. The US Constitution: 1789-1994. RIP. ------------------------------ Date: (null) From: (null) "Regarding the lack of a memory Lock Out function, I talked at length with the Kenwood people. They have been inundated calls about this and have told me that they are preasuring Japan to come up with a processor replacement to fix this, perhaps as a retrofit. I encourage any owner of a TH-79 to write to Kenwood insisting on such a modification at no cost and asking that they be informed when it is available. I think this is justified for several reasons. First, I have been told by another ham that the official brochure indicates that such a feature is included. Second, and more important, it is arguable that the radio is not suited to the application without memory lockout. After all, it's an 80 channel radio. To make effective use of that many channels REQUIRES a channel lockout function. Without effective use of that many channels, the radio is not comparable to the current standard for such a unit. BTW, close inspection of the RF deck in my radio shows no obvious missing parts. I didn't remove the board to check the other side, but my suspicion is that the 800 MHz parts are installed. I'd be interested in input from others on that. So far I've not discovered how to make it display any 800 MHz frequencies though." ======================================================================= Kenwood TH79 Dual Bander Modification and Feature Guide r1.5 The End! ======================================================================= ------------------------------ End of Info-Hams Digest V94 #1039 ******************************