[amsat-bb] Re: AO-07 Distorted audio

[Paul Stoetzer]

Absolutely!

The recommendation at the time of launch was to limit power output to no
more than 100W ERP (which is about 25 watts to a small antenna like an Elk
or an Arrow). This is even more critical now since the solar panels are
almost certainly not supplying enough power to drive the transmitter to
it's full power output. At certain times of the year, there are poor solar
angles on the panels too, which reduces power availability. Remember too
that AO-7 will enter a period where it eclipses on every orbit over the
south pole within the next week or so. That period will last for about 9
weeks. It should be in Mode B every day as a result, but from what I've
read about past eclipse cycles, it can act a bit odd during that time.

On too many passes, I hear distorted audio and reflections throughout the
transponder from it being hit too hard with SSB and especially CW. CW,
being full power at key down, unlike SSB, is even harder on a linear
transponder.

If everyone would just have the courtesy to keep their uplink power to a
reasonable level, AO-7 can be a very enjoyable satellite with a large
footprint providing the best DX opportunities currently available.
Unfortunately, this problem is not new as a glance at the AMSAT Newsletters
from 1974-1981 shows.

I recommend the following reading: The Editorial + Letter from W4NUL/5 in
the March 1976 AMSAT Newsletter, the AMSAT-OSCAR-7 QRP Test Telemetry
Report in the November 1976 AMSAT Newsletter, and the June 1976 QRP Test
Results from the December 1976 AMSAT Newsletter. All available here:
http://www.ka9q.net/AMSAT-Newsletter-1976.pdf

Please calculate your ERP ( http://www.csgnetwork.com/antennaecalc.html )
and keep it to no more than 100W.

73,

Paul Stoetzer, N8HM
Washington, DC


On Fri, Apr 25, 2014 at 11:12 AM, Dave Webb KB1PVH <kb1pvh at gmail.com> wrote:

> Only when people are running too much power. It's called FM'ing.
>
> Dave-KB1PVH
>
> Sent from my Verizon Wireless Droid RAZR
> On Apr 25, 2014 11:10 AM, "Peter Wilson" <protest at virginmedia.com> wrote:
>
> > Just worked IK8YSS on AO-07.
> >
> >
> >
> > Haven't worked this satellite for a while and whilst I know the bird is
> > very
> > old, the audio on this pass was very distorted.
> >
> >
> >
> > Is this common?
> >
> >
> >
> > Peter
> >
> > G8KEK
> >
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