Hi Ralph, I've never seen this before but I have a few questions. Is
it possible that your highly calibrated Voice has components at this
PL freq. that could trigger the "reverse cut off feature" or cancil
out the received tone? Try looking at the input to the tone decoder
board for the tone while doing the "test". Try a few different CG
frequencies. ..... May be it's that youre using "PL" on a GE and
not "CG"....GRIN...(;-)
MERRY CHRISTMAS !!!
AC0Y
--- In Repeater-Builder@yahoogroups.com, "Ralph Hogan" <[EMAIL PROTECTED]>
wrote:
> Working on an IDA control shelf equipped UHF GE M2 base/repeater.
Normally
> used to working with a lot of the
> older card rack style control shelves. Never saw this happen on
other GE M2
> repeaters or mobiles.
>
> Here's the situation:
>
> I am using the repeater system looking at RUS for PL detect and
CAS for COS.
> Either running repeater in stock IDA repeat mode, or externally
wired RC-85
> controller.
>
> Using an HT on the bench if I hit the audio hard getting close to
4.5 KHz
> peaks the repeater would shut down
> in PL mode (127.3 Hz FWIW). If I run in COS only mode, no issues.
I had
> originally thought perhaps it was something in the IDA control
shelf, since
> this is my first IDA equipped machine. Probing around saw that U7A
4066 in
> the IDA was muting the RX audio vol/sql hi to TX audio hi path.
That control
> line leads to RXMUTE (amoungest other sources) which started me
looking at
> the PL decoder.
>
> Used a pl deck extender card to isolate the PL deck's RXMUTE
decode signal
> from the IDA. Its the decoder for sure, rxmute high (pl detected)
on low
> level audio and rxmute drops low (no pl decode) on loud voice
peaks.
>
> This is a GE stock digital PL decoder. Swapped in another ge pl
deck. Same
> deal. Swapped in a TS-64MII and it also does it, but not as bad.
>
> I even went so far as to look at R608 audio preamp pot inside the
shielded
> box on the audio/sql board. It adjust the VOL/SQL hi signal toward
the pl
> detector. Its adjusted within limits and didn't make any
difference.
>
> I swapped out the GE RX front end and audio/sql boards with known
good ones
> just for grins thinking distorted audio. Not the problem.
Rechecked the rx
> chn element freq using the F-11.2 trick on the service monitor.
It's dead
> zero'd.
>
> This effect happens on several HT's on hand. Main 'test bench' HT
measured
> 650 hz pl dev and 4.5 KHz dev voice peaks. Audio source, my highly
> calibrated voice 'Ahhhhhh 1 2 3 W4XE' hihi..
>
> Now I can fully understand a real distorted audio signal or one
that's way
> over deviated out of the receiver limits not being decodable. But,
I can't
> ever remember being able to talk off a pl decoder on innumberable
GE M2's
> I've had on the bench before.
>
> The only new variable is this IDA shelf and maybe the system
interface board
> in the drawer. Haven't compared it to a card rack version to see
if they are
> different. But, not much to go wrong on that system interface
board in any
> case.
>
> Thought I'd throw out an email while everyone is sitting at home
dreaming
> about sugar plums..
>
> Has anyone else seen this problem?
>
> 73's and happy holidays
> Ralph W4XE
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