Petrusse Excalibur 2002 squelch pop mod advice needed.

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The Collector
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Petrusse Excalibur 2002 squelch pop mod advice needed.

Post by The Collector » 30 Sep 2017, 16:51

Hi all.

I'm looking to mod the above radio to get rid of the infamous Cybernet-boarded squelch pop.

After looking on here, I found Ashtec had sussed out that adding a capacitor to the boards seemed to do the job nicely. I don't mind a bit of white noise when listening for weak signals so decided again getting a noise squelch fitted. Not that I use radios to be honest ;)

I've bought a Panasonic 16v 10uf (whatever that means) capacitor as Paul recommended but need to know where in the board to fit it.

I believe the board to be a PTBM131A4X from what Crusader put on a post a while back.

Anyone know where/how this has got to be soldered?

Cheers.

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Re: Petrusse Excalibur 2002 squelch pop mod advice needed.

Post by ChrisMagpie » 30 Sep 2017, 22:58

The Collector wrote:Hi all.

I'm looking to mod the above radio to get rid of the infamous Cybernet-boarded squelch pop.

After looking on here, I found Ashtec had sussed out that adding a capacitor to the boards seemed to do the job nicely. I don't mind a bit of white noise when listening for weak signals so decided again getting a noise squelch fitted. Not that I use radios to be honest ;)

I've bought a Panasonic 16v 10uf (whatever that means) capacitor as Paul recommended but need to know where in the board to fit it.

I believe the board to be a PTBM131A4X from what Crusader put on a post a while back.

Anyone know where/how this has got to be soldered?

Cheers.
I'm not much of an expert, but I've done Ashtec's squelch mod to two Radiomobile CB201s now, and it works great! :thumbup:

Ashtec's mod here:
viewtopic.php?f=53&t=30803&start=30
Schematic for PTBM131A4X here:
http://www.cbtricks.com/radios/supersta ... 00_sch.jpg

I'm looking at the schematic, and thinking the squelch switching transistor is Q28, as that's grounding the audio preamp, and the base is connected to the "squelch gubbins". If this is right, the negative lead of your new 10uf capacitor would go to Q28's emitter (which would be easy to spot, as it goes to ground, so it goes to the "common foil" on the circuit board, [which is the foil that snakes all around the board]) . . . and the positive lead of your new 10uf (micro farad ;) ) capacitor would connect to Q28's collector (which will be the foil trace that arrives at the junction of R150 and C155).
I am out of my depth here, though :shifty: It would be great if someone lots more cleverer than me could cast their beady eye over the schematic, and let us know if we're on the right track, or if I'm embarking up the wrong tree!
Best of luck bro :mrgreen:

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Re: Petrusse Excalibur 2002 squelch pop mod advice needed.

Post by The Collector » 01 Oct 2017, 15:55

Most of that went "whoosh", straight over my head lol ;)

It might be best if someone would kindly expand a picture of the right area of the board and put some arrows on it saying long leg goes here and short leg goes here! Q-blah this and collector-foil ground emitter trace dooberry thingymijig means bugger all to the likes of me.

I bought the capacitor ..that's about the limit of my component expertise :)

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