[amsat-bb] INTERMITTANT DOWNLINK HEARD - CAS-4A transponder freq

Paul Stoetzer n8hm at arrl.net
Thu Jul 27 22:02:17 UTC 2017

An FM signal with no modulation is theoretically just a carrier, no
different from CW. So it wouldn't really be a problem to send a couple of
quick transmissions to test it out.

FM signals won't harm a transponder, but they will cause a lot of problems
for others trying to use the transponder.


Paul, N8HM

On Thu, Jul 27, 2017 at 17:41 Scott <scott23192 at gmail.com> wrote:

> Had hopes of monitoring some voice transponder activity on a high pass of
> CAS-4A this evening, but nothing heard.
> The telemetry data stream and CW beacon were strong as ever, but nothing
> around the transponder downlink.
> Image of SDR waterfall:
> http://www.qsl.net/k/k4kdr//files/2017-07-27--2124--CAS-4A.png
> Question:  in a case like this where the status of a transponder is unknown
> and no activity is heard, absent any SSB gear would it be bad to transmit
> an FM signal on the uplink just to see if the transponder is in fact
> active?  I would never use FM if there was activity, but could an FM
> transmission cause any harm just to possibly determine the status of a
> transponder?
> Thanks!
> -Scott,  K4KDR
> ==========================
> On Wed, Jul 26, 2017 at 9:31 PM, christy hunter <cchunter3 at mindspring.com>
> wrote:
> > to All, this is to confirm my status report on the website, (in case you
> > think it was a mistake)
> >
> > on July 27 2017, at about 0047UTC I could hear my downlink, although
> > intermittently, during a pass of CAS-4A (using the published
> frequencies).
> > The downlink had good audio (loud and clear), and I could only hear a few
> > words of my transmission at a time. I was able to sustain for only a
> > portion of the pass. Using 5Watts into a M2 16 el cross element circular
> > beam. (436CP16). This pass did NOT coincide with any of the XW sats.
> >
> > 73, Christy KB6LTY, DM14
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