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Author Topic: Programming HT for Doppler effect  (Read 999 times)
S109
Member

Posts: 15




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« on: March 14, 2014, 03:47:37 PM »

Hello,

I'm new to working satellites and I don't really seem to be having much luck in just hearing anyone. I'm using a Kenwood TH-F7E and I've recently got the Arrow antenna. I use GoSatWatch to track the satellites, normally listen to AO-73. I have my HT programmed with the memory channels starting with 145.950, 955, 960, 965 ending with 145.970. With the satellite at its highest point I should be hearing people around 145.960 correct ? I am hearing people but can never really fine tune the signal so I can't make out the call sign etc. Should I program the HT with finer gaps, how do you program your spacing for the satellite rx frequencies ?

Thanks. 
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M6SWA/2E0SNJ
WD9EWK
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Posts: 239


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« Reply #1 on: March 14, 2014, 04:50:51 PM »

Hello,

I'm new to working satellites and I don't really seem to be having much luck in just hearing anyone. I'm using a Kenwood TH-F7E and I've recently got the Arrow antenna. I use GoSatWatch to track the satellites, normally listen to AO-73. I have my HT programmed with the memory channels starting with 145.950, 955, 960, 965 ending with 145.970. With the satellite at its highest point I should be hearing people around 145.960 correct ? I am hearing people but can never really fine tune the signal so I can't make out the call sign etc. Should I program the HT with finer gaps, how do you program your spacing for the satellite rx frequencies ?

Thanks. 

You'll be better off if you don't bother with memory channels when trying to hear SSB downlinks like AO-73 with that HT.  I have the North American twin to your TH-F7E, the TH-F6A, and I never bother with memories for anything - especially trying to receive SSB.  Just put VFO B into USB, set the tuning step down to a small number (I use the smallest setting, 33 Hz, but some use these radios at 100 Hz), and tune across the transponder that way. 

SSB satellites like AO-73 (this also includes AO-7, FO-29, and VO-52) are not single-channel repeaters like SO-50 and the previous AO-27, AO-51, and a few others.  Add in Doppler, and memory channels just don't work well.  AO-73 has the smallest transponder of the 4 SSB satellites at 20 kHz wide, where FO-29 has the largest at 100 kHz wide.  Most activity is near the center of each transponder.  You could start out at 145.960 MHz USB on AO-73, and tune up or down from there.  With the small tuning step, you'll be able to adjust the VFO to clean up the voices you hear.  The smaller tuning step means you will be spinning the VFO knob a lot to tune across most transponders from end to end, but you'll probably find that most activity is around the center, and not all the way out to the far ends of the transponder. 

In general, most SSB activity will be up from the center of each transponder, and CW will be below the center of the transponder - just like how you'd hear on most HF bands.  Sometimes the SSB activity will slip a little below the center of the transponder, and you'll sometimes hear SSB all over the smaller AO-73 transponderwhen operators are trying to find an open spot to make QSOs.

73!
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Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
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