[amsat-bb] Re: AO-51 Signal Strength Post Flip

Mark L. Hammond marklhammond at gmail.com
Tue Feb 9 10:41:44 PST 2010

Thanks for the reports.

Again, I encourage you all to research the power levels OUT at the
comparison times.  That has to at least be considered in the

For example:

Power is "watts" out

Date                                   435.150  435.300   Battery V

Before flips

2009-02-09 19:27:04 oz7sat   0 0.779 0.859 7.660   <--- 859 mW one
year ago!  compare to today, listed below!

2009-10-25 18:17:01 oz7sat   0 0.452 0.617 7.868

2009-11-25 17:41:51 oz7sat   0 0.361 0.744 7.581 <-- 745 mW before the flip!

2010-01-15 18:45:31 oz7sat   0 0.437 0.462 7.892


2010-02-09 17:19:06 oz7sat   0 0.452 0.475 7.752 <-- 475 mW today!

We are running a few hundred milliwatts below what we were running
pre-flip, and a good bit less than we were able to run a year ago.
So you all may be seeing the difference between 600-850 mW and 475 mW.
   It's real.

Yes, the bird is aging, and we're doing the best we can to manage the
resources available on-board (the limits now are orbit and battery
condition) .  The full illumination periods in the last year or two
have taken their toll on the batteries.   What will be interesting is
to see what happens when we return to periods of eclipse!!
Personally, I don't expect the situatio to improve, although it might
be that the batteries will cool and some capacity will return.  But
we'll need it with eclipses.


Mark N8MH

> In the past few weeks, I've often had problems hearing AO-51 here in DO33.  A year ago, signals of at least S3 on my FT-817ND were common.  Now they are weaker.
> As well, I get the impression that the signal polarity has changed.  Formerly, I could hold my Arrow dual-band Yagi with the 2 m elements nearly horizontal and still hear the satellite.  Now, I have to turn it nearly 90 degrees, sometimes changing the orientation more than once during a pass.
> Some of that I might attribute to my operating a portable station within a  residential area in the city, but I definitely noticed a significant difference between what I hear from AO-51 now and what it was before the satellite was flipped.
> 73s
> Bernhard VA6BMJ @ DO33FL
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Mark L. Hammond [N8MH]

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