Noise Squelch in Cybernet 134

[Mudslinger]

This is a different mod Muddy, and much, much, much better than that mod you are referring to

In that case I am willing to try it...

But it won't be on my CBX as I don't want to break the factory seals.

[Ashtec]

Glad its worked for you............
I'm a Cybernet fan but my only pet hate with them all is the dam Squelch pop they have they drive me to the point of switching them off

But the other day i got a Ham International Puma and it was driving me up the wall so i set out to sort this problem once and for all.
So out come the oscilloscope and i had a play with all different ideas to stop the popping but i found that the 16v 10uf cap across the emitter & collector of the squelch transistor was the cleansed in action and easy for all to do with out removing parts and replacing with others.
I found the 16v 10uf cap was the best value to use as other value's do put a bit of a delay on the squelch.

Im not a big fan of the move the wire mod as it pulls the FM detector ic's output to ground which may damage the FM detector ic over time and i wasn't impressed with the way it sounded or worked..........

[Buick Mackane]

Just done this mod on both my harrier CBX & radiomobile 202. Seems to work a treat, It also does away with that annoying speaker rumble you get just as the squelch is about to turn on/off

Nice one ashtec

[Ashtec]

Glad its worked for you..............

[The Collector]

Personally I'm fed up with everyone soldering bits onto me

[163TM847]

The best mod ive found to work after playing about with these radios is put a 16v 10uf cap across the emitter & collector of Q14 this sort's the popping and banging sound out on these radio's ive found............

[CENTER]
[/CENTER]

The Noise Squelch dose work well but they don't take to well to CB'ers over deviating.

This mod also work's well on the Ham International Puma but put the 16v 10uf cap across the emitter & collector of Q12

Just tried this in an SMC Oscar i got in for repair, Works fine no annoying popping when signals break the squelch now.

Cheers Paul

[Ashtec]

Glad its worked for you Nick

[ChrisMagpie]

The best mod ive found to work after playing about with these radios is put a 16v 10uf cap across the emitter & collector of Q14 this sort's the popping and banging sound out on these radio's ive found............

[CENTER]
[/CENTER]

I've done the mod today on a Cybernet PTBM135AOX (Radiomobile CB201)
The squelch transistor Q14 on the 134 board is also called Q14 on the 135 board.
The collector of Q14 connects to a 10K resistor on both boards. Emitter goes to ground.
Schematic on CB Tricks of the 134 (Rotel 240) shows Q14 as a 2SC945 and this 135 board had a Q14 using a JC501Q.
I checked the datasheets, and the pinouts are the same

No room for the capacitor on the solder side of the 135 board, as the rig case fits closely to the board.

radiomobile1.JPG

I spotted an unused through hole on the trace to the emitter of Q14, so used that for the capacitor ground.
I unsoldered one end of the 10K resistor connected to the collector, enlarged the hole with a small drill, scraped off a bit of the etch resist, to give a bit more track to solder to, then resoldered the 10K resistor, along with the new capacitor.
Before:

radiomobile2.JPG

After:

radiomobile3.JPG

Works nicely. Looks almost factory

[Ashtec]

Glad to see this mod is used and helpful to a few of you... It was always my pet hate with cybernet set's the squelch popping.
Ie why I had a play to find a fix for it...

[The Collector]

I'm trying to pluck up courage to fit a resistor in my Petrusse Excalibur to stop it popping, but you know me and the insides of radios don't get on

[Ashtec]

I'm trying to pluck up courage to fit a resistor in my Petrusse Excalibur to stop it popping, but you know me and the insides of radios don't get on

Umm the radio you have collector isn't as easy as the early cybernet Chassis were a capacitor can be used....I will have to have a good think and get back to you..

[Ashtec]

[The Collector]

Hmmmm...thanks Paul Might have to wait until I'm taking a few radios to a rig doctor though and ask if they can do that to it.
I'm not sure if I could be trusted to perform minor surgery on it and not bugger something up!

[Ashtec]

Hmmmm...thanks Paul Might have to wait until I'm taking a few radios to a rig doctor though and ask if they can do that to it.
I'm not sure if I could be trusted to perform minor surgery on it and not bugger something up!

Mitch did post a capacitor mod for your radio that you could try.. I wasn't impressed with the mod but it is each to there own how you whanting the squelch to work...

[The Collector]

Now if I could simply solder a capacitor onto the speaker wire or something like that, even I could handle it

Cheers Paul and welcome back once more mate!