[amsat-bb] Doppler Tuning Convention Question

John Belstner jbelstner at yahoo.com
Mon May 31 13:35:43 PDT 2010

I know there is a lot of discussion on this subject in the AMSAT archives, but I've recently read a few posts to the BB that have me confused.

Just this weekend I got my Sat station on the air (FT-736R w/MacDoppler) and I noticed that the MacDoppler program I use adjusts both the TX and RX frequencies during the satellite pass.  I'm assuming this is to keep my signal located in the same place in the transponder.  The program seemed to work quite well.  I was able to copy several QSO's on VO-52 and made a couple contacts as well.

One thing I noticed is that about half the QSO's I copied did not require any manual tuning on my part (MacDoppler adjusted the RX correctly) while the other half did.  According to MacDoppler, those that did require manual tuning were moving around within the transponder passband.

I've read a few posts (one as recent as today) that suggested the convention is to keep the RX frequency fixed and manually adjusting the TX frequency while monitoring the downlink.  Looking through the AMSAT archives this is the old convention prior to the popularity of tracking software and CAT control.  So my question is, are there two conventions? or do I not have my software configured correctly?

Sorry for what might seem like a stupid question, but I'm a newbie to this facet of Ham Radio.  BTW, I'm having a blast!


John Belstner
w9en at arrl.net

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