High temperatures depress the downlink frequencies. AO-85 has just finished an 11 day period of continuous illumination which normally increases the temperature 30-35 C. Low battery voltage is also a factor. It is still seeing very short eclipses, but that will return to normal over the next few days.
73,
Alan WA4SCA
<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Hasan <al-Basri via AMSAT-BB <Sent: Sunday, November 03, 2019 05:19 AM <To: James Pierce james@thirdglance.com <Cc: AMSAT-BB amsat-bb@amsat.org <Subject: Re: [amsat-bb] AO-85 Downlink Frequency Shifted Down 2.5Khz ? < <Yes it is off freq (often) and by the amount you mentioned. I'm guessing it <is thermal. <73, N0AN < <Hasan < <On Sun, Nov 3, 2019, 1:43 AM James Pierce via AMSAT-BB <amsat- bb@amsat.org <wrote: < <> The last couple of passes I’ve chased AO-85 over Australia the downlink is <> appearing about 2.5Khz lower than expected. <> <> I am uplinking at 435.170 and was expecting the downlink at 145.978.6 … <> however it seems the return is arriving at more like 145.976.1- The signal <> coming back is excellent once tuned, especially while the bird is higher in <> the pass. And yes, for anyone wondering, I use macdoppler for full doppler <> tuning through the whole pass. <> <> Can anyone shed any light as to what may be happening? I’ve always found <> AO-85 to be a very quiet bird over Australia, and I wonder if this may be <> part of the reason. <> <> James - VK3VJP <> _______________________________________________ <> Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <available <> to all interested persons worldwide without requiring membership. <Opinions <> expressed <> are solely those of the author, and do not reflect the official views of <> AMSAT-NA. <> Not an AMSAT-NA member? Join now to support the amateur satellite <program! <> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb <> <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions <expressed <are solely those of the author, and do not reflect the official views of AMSAT- <NA. <Not an AMSAT-NA member? Join now to support the amateur satellite <program! <Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb