[amsat-bb] Is there any frequency error on the AO-7 Mode A transponder?

Scott Armstrong aa5am at arrl.net
Wed Dec 1 07:32:30 PST 2010

Hi all,
I am new again to satellites after a 30 year absence.  I recently began operating on AO-7 ,Mode A, since that is the only bands I currently have equipment for.
Over the past  few weeks while trying to find my downlink signal, it seems to be farther off in frequency than I would expect it. Even after taking the doppler into consideration. 
I know there is some error on my transmit side but the receive side is fairly accurate.
Is there any frequency error associated with the Mode A transponders? If so how much error?   
Ideally, ignoring doppler associated with the uplink and downlink signals and any frequency error associated with my transmitter and receiver, an uplink signal of 145.9000MHz should result in a downlink signal at 29.45000 MHz.
Thanks in advance,
Scott AA5AM

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