Hi Bob,

There are many reasons why the transponder "constant" varies somewhat. The temperature of the satellite is somewhat dependent on sun angle, periods of eclipse, etc. This usually results in a slow seasonal variation, most frequently seen in SSB satellites, but also in some cases in the FM birds. In the case of AO-7 there is no battery to stabilize the voltage, so at some (most?) times the 39 year old arrays may not provide enough power for a completely stable output. I recall an article on the subject in the AMSAT Journal, though I don't have it handy.

73s,

Alan WA4SCA

<-----Original Message----- <From: amsat-bb-bounces@amsat.org <[mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bob- W7LRD <Sent: Monday, November 18, 2013 11:00 AM <To: amsat-bb@amsat.org <Subject: [amsat-bb] AO7 calibration < <Hello...More often than not I have to "adjust" the up link <calibration on satpc32 in order to accurately track the sat. <It is not always the same adjustment, it can vary from a few <cycles to as much as 2.5 khz. Given AO-7 is a grand old lady, <is she just being temperamental, or do I have an issue <(operator error). <73 Bob W7LRD <_______________________________________________ <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 <