Cobra 29 NW squelch issue?

[secret squirrel]

I have never experienced this issue before. Local tech says the squelch is adjusted right. Personally I think he does not want to play with it. The squelch does not open up crisp, when you adjust the dial- let say turn the squelch down- you have a decrease in volume then a delay, then the channel opens up. I never had a CB do this, even the Pearce Simpson Pussycat 23 I have sitting on my desk from 1973 the squelch is a pretty clean break its either open clear channel, or the squelch level is set. If you adjust the RF gain so the squelch works like I think it should, then I just reduced the receive to next to nothing. Second there is a very low hum that will not go away unless I crank the squelch up pretty high. I think its the face plate LED, if I dim it all the way the hum goes away. This is a 2004 model out of a water tanker. Its been knocked around pretty good.

 

[Handy Andy]

2004? Pretty old - and when you get a chance, you may need to replace C36 that cap cushions the "thunk" you usually hear thru the speaker while the squelch opens and closes.

Tends to slow down and even take in the audio along with it - as the cap ages, it's ability to retain a sharp linearity for audio changes - it's a response to age.

Most of the time it's a 33uF - but you can lessen the value to about 10uF - you will hear a thunk but it will respond crisper to that threshold. Original 16 volt value works but you can go up to 25 Volt rating to ease the cost.

As far the the "nightwatch" illumination, they tend to get noisier as they age - to a point where it will be dim in many spots and won't go as bright as it once did, the membrane that separates the plates is what causes this - the plates it separates and the embedded phosphor within - tends to oxidize and stress pressure, humidity and temperature adds to the demise - the environment it's in diminishes its' ability to illuminate evenly as it ages. The noise it makes is from the dimmer unit, and if its' been in the shop more than once, if they mess with the dimmer or have to move it out of the way to work on other sections. The re-routing and any kinks will add to the field effect noise and hence affect the ground plane and any close wires carrying audio - located close by.

The reason why he may not want to work on it is from the rework and layout of that EL wire feed to the front panel - not properly routed, or it got pinched, it acerbates the failure and the increased noise too.

 

[secret squirrel]

Thanks for the come back. Much appreciated.