[amsat-bb] Re: AO-07 Distorted audio
protest at virginmedia.com
Tue Apr 29 14:28:49 PDT 2014
Thank you for such a detailed response, for a newbie like me (only 63 years old) this is all very interesting - and logical.
As you quite rightly say, this satellite should be treasured due to its footprint………..
From: prstoetzer at gmail.com [mailto:prstoetzer at gmail.com] On Behalf Of Paul Stoetzer
Sent: 25 April 2014 19:23
To: Dave Webb KB1PVH
Cc: Peter Wilson; AMSAT -BB
Subject: Re: [amsat-bb] Re: AO-07 Distorted audio
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.
Paul Stoetzer, N8HM
On Fri, Apr 25, 2014 at 11:12 AM, Dave Webb KB1PVH <kb1pvh at gmail.com <mailto:kb1pvh at gmail.com> > wrote:
Only when people are running too much power. It's called FM'ing.
Sent from my Verizon Wireless Droid RAZR
On Apr 25, 2014 11:10 AM, "Peter Wilson" <protest at virginmedia.com <mailto: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
> old, the audio on this pass was very distorted.
> Is this common?
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