There are some very good reasons to NEVER use FM on a linear transponder, especially FO-29 and AO-7.
Since FM is running a constant carrier, it sucks all the available power away from other users on the transponder, and makes the transponder run a full-carrier on the output. This is VERY hard on the power system of a satellite that was never designed for it, and particularly hard on the batteries of an older bird like FO-29. Since AO-7 is running entirely on its solar cells, forcing it to transmit a full carrier would drag the system voltage down to where it would probably reset the satellite, and possibly cause other damage. If you want to run FM, stay on the FM satellites and keep off the linear birds! Jim KQ6EA On 04/23/2011 08:37 PM, Kevin Deane wrote: > > Or he could just use FM since hardly anyone uses the SSB birds compared to > the other sats. > > Although I am sure there are a million reasons not to use FM. even though it > works just fine on the SSB birds. The feedback I got from the FO-29 Control > Team was that SSB was pretty much "the rule" or "band plan" if you will. > > I may be wrong in my opinion, but I dont see why we cant use FM other than to > keep usage down? I hope everyone dosent freak out, as this seems to be "Taboo" > > Kevin > KF7MYK > > >> To: amsat-bb@amsat.org >> From: k...@aol.com >> Date: Sat, 23 Apr 2011 15:08:12 -0400 >> Subject: [amsat-bb] Re: FO 29 help >> >> >> Ted, >> It sounds like you are hearing a "reflection" of your signal, not the >> downlink from FO-29. This is a common malady associated with 3rd harmonic >> interference on mode J (V/U) satellites. Try this on a pass that will reach >> at least 30 degrees above the horizon: >> 1. Turn HRD control of your TS2K off >> 2. Set your uplink at 145.950 CW >> 3. At AOS you should hear the beacon about 8-10 kHz above the beacon freq of >> 435.895 (about 435.904 MHz) >> 4. Tune your receiver to 435.850 plus that same delta from beacon (about >> 435.859 USB). You should be able to tune your receive and hear your CW dits >> (clearly). >> 5. Zero beat the CW dits on the low side, switch to LSB and you should be >> exactly on frequency and can turn on TRACE and go anywhere in the passband. >> >> If you have auto-Doppler turned on in HRD, your program should do the same >> thing as this manual procedure. >> >> You should be able to hear yourself. If not, Google the diplexer fix for the >> harmonic problem. >> >> > From the center of the passbands, whatever the UHF Doppler shift is, the >> > VHF Doppler will be approximately 1/3 in the opposite direction. This is a >> > helpful rule for finding your downlink manually. >> >> 73, >> Jerry, K5OE >> >> -- original message -- >> Good morning, >> >> Since putting up the Elk on a rotor (fixed el +- 25 deg), I decided to try >> some linear birds. >> >> I have tried FO 29 about 3x but seem to have some issues. I am using TS-2000 >> in SAT mode with HRD Sat program. >> Up: 145.9 LSB >> Dn: 435.8 USB >> >> I am clearly able to track the bird with doppler as I can hear the CW beacon >> through the entire pass (switching back and forth). I can also TX into the >> bird and hear my signal coming back duplex. However, what is coming back is >> my voice signal but totally unintelligible. Also, I have heard no other >> stations on these passes. >> >> Am I doing something wrong? >> >> Tnx for any help >> >> Ted, K7TRK >> >> >> >> _______________________________________________ >> Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > _______________________________________________ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
