Squeqling noise from VHF systems saber 3

[Fireman26]

Has anyone ever heard of this problem!

My systems saber squeals out of the speaker, and I cannot find the problem, This just started and the radio tX and RX fine! Only RX audio has this problem, I would figure the speaker but its fine! Even the case is ok!

ANY IDEAS out there would be helpful thanks!

I use this radio for Amateur bands and for Search and Rescue!

[fire_master_21]

how many channels are effected? Have you hooked a should mic up to thr radio? if so does it still squeal?

[phrawg]

Sounds like some component has become "microphonic".
That means that it is picking up vibration from the speaker
and that is affecting the way the circuit works. Kind of a
feedback loop happening. I would first open the radio and
see if there is a module loose just enough to cause this.
Maybe carefully re seat them in their sockets. also look at
screws that hold a couple of them in place through the
mother board. Carefully make sure they are snugged up
but not over tight. Do a general inspection for something
out of place or shifted in a way that would allow speaker
vibration to make circuitry vibrate with it. A few clues
to help you , is it more of a problem at high volume
and do you have a speaker mic you could try on it.
That will prove that is a microphonic component or it is
a microphonic caused by maybe a bad solder joint or
similar such thing. Hope this may help, Phrawg

[Fireman26]

Yes this happens at high volume!

I will take the radio apart and do a visual inspection

Thank you for the fast reply

Larry

[DJP126]

Sounds like Phrawg hit the nail on the head for you. If the radio is microphonic, the VCO is the most common cause (but very seldom seen in a VHF model). His recommendation of checking the hardware is exactly what to do first, then try swapping the VCO (if you have access to a spare one).

[Fireman26]

Thanks guys,

Its always a pleasure to deal with the experts!

I will check the unit this evening

Larry

[AEC]

I second the microphonic VCO...swap U4 and look for the proper filter number inside as well...for the band split the radio is programmed for, this should also help.

NFD9462 is the proper filter number for the 146-174 band split.