[App_rpt-users] [Bulk] Issue with Hangup after first keying

Bryan D. Boyle bdboyle at bdboyle.com
Wed Jul 3 23:17:53 EDT 2013

On 7/3/2013 7:37 PM, Joshua Hintze wrote:
> Thank you for all the suggestions thus far.
> I'm using an ICOM IC-A110 VHF radio. I was able to find some
> schematics/block diagrams in the service manual here:
> http://elektrotanya.com/icom_ic-a110,_a110e_service_manual.pdf/download.html
> This is my first time trying to dig through a radio and find a COR. I'm not
> sure either where to get a discriminator audio signal either.

Detecting squelch break in AM is a lot different that breaking squelch
in FM...

iirc, you have to depend on the AGC circuit to do what it's supposed to
do in order to detect a signal level delta greater than the background
hash, which is a variable.  FM looks for the detector to open up when
the frequency swing happens...a bit more binary than AM transmissions,
which means there's a constant noise level vice AM (just listen on the
HF bands to see the difference in the noise levels from minute to
minute...).  Kind of hard to detect amplitude changes as being a
legitimate carrier vice noise, since they're both the same general
modulation envelope, whereas in FM, the intelligence is carried in a
different mode than the background noise.

Don't know whether I'm explaining it clearly enough, but it's in that
general neighborhood or some such.

Just what are you trying to do?


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