On Fri, 8 Oct 2010 12:30:07 EDT, I wrote:

On Fri, 8 Oct 2010 10:10:09 EDT, John Davis
wrote:

On 10/7/2010 12:45 PM, Dick Grady AC7EL wrote:

Can anyone explain the above phenomonon?

Dick AC7EL
One thought.. What is the "Hang time" on that repeater... (From the time
received signal stops to the time xmtr cuts off.

It could be the signal was not holding it and it was fluttering the
transmitter (Rapidly switching on and off) and your S-meter was averaging.

The hang time is zero, literally. A while ago, I asked the tech
committee why there was no hang time, and they said that to save money
they did not add a controller board.

So your explanation makes sense.

Dick AC7EL

Further thoughts on the mechanism:

Our repeater has zero hang time, because we don't have a controller
board. So if he was just barely opening the squelch, and the squelch
was fluttering rapidly, then the repeater output was being switched on
and off rapidly, and my S meter was averaging the on/off signal. We
could understand Andy because of the redundancy in human speech.

I can think of two mechanisms for the rapid flutter of the squelch.
One is noise in the receiver front-end.

The other is desensing of the receiver from the transmitter. Every
time the transmitter keys, the receiver desenses slightly (those
filter cans cannot suppress all of the transmitted signal at the
receiver input), which makes the received signal seem weaker, which
closes the squelch, which turns off the transmitter, which stops the
desensing, which makes the receiver sense Andy's signal large enough
to open the squelch, ... and this cycle repeats and repeats. On a
stronger input signal, the desensing will not cause the squelch to
close, and the transmitter would not be rapidly switched on and off.

My guess is that desensing is the reason for the observed phenomenon.

Dick AC7EL