This is the way it has always been with this bird, I posted this about a month ago....

From: Jeff Griffin [mailto:kb2m@comcast.net] Sent: Monday, December 9, 2013 9:38 AM To: 'amsat-bb@amsat.org' Subject: RE: [amsat-bb] Re: Auburn sat

I also worked AO-73 for the first time this weekend (thanks all involved for the new sat) and noticed the frequency shift also. As the bird came up I found my D/L at about 5k higher than the advertised center frequency. What was different was that by the end of the pass, the D/L ended up about 10k higher than the Doppler adjustment supplied by PCSat32. It was like, as the transponder was being used and warmed up it went higher in frequency. I found that during several QSO's I made, I had to adjust the D/L up several times. As I had just worked VO-52 this was noticeably different. I'm not complaining, I just thought this worth mentioning :-)

73 Jeff kb2m

-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Andrew Glasbrenner Sent: Friday, January 10, 2014 4:43 PM To: Peter Wilson Cc: amsat-bb@amsat.org Subject: [amsat-bb] Re: AO-73 Doppler shift

Yep, it drifts. Best to tune that one by hand in my opinion. G0MRF addressed it in an email to the -bb a while ago if I recall correctly.

73, Drew KO4MA

Sent from my iPhone

On Jan 10, 2014, at 4:26 PM, "Peter Wilson" protest@virginmedia.com

wrote:

Hi all,

I'm having great fun on all the operational satellites, including AO-73.

However, I find that even using CAT control I have to adjust the uplink frequency almost constantly throughout the pass.

I have to shift buy about 3500Hz overall from start to finish, increasing all the time.

Is everyone else seeing the same effect?

Peter

G8KEK

---

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_______________________________________________ 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

According to Wouter, PA3WEG, who designed the AO-73 transponder, PLL frequency generation is possible now within the power budget of a 1U CubeSat, but was not when the FUNcube's transponder was designed.

See his post from last month:

http://amsat.org/pipermail/amsat-bb/2013-December/047815.html

73,

Paul, N8HM

On Sat, Jan 11, 2014 at 9:22 AM, Rich/wa4bue richard.siff@verizon.net wrote:

AO7 and FO29 seem to be very stable. VO52 was my first experience with a drifty transponder oscillators. I read some explanations on the BB.

What design element needs to be changed to stabilize the linear transponders oscillators on the new CUBESATS.

Are the beacons crystal controlled?

Rich W4BUE _______________________________________________ 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