Mic squeal through Ext . spreaker on AM

[357magnum]

This is what I have Turner JMU + 2 mic , Cobra 140 GTL an a King Bee 250 ( I think made by Palomar ) when I key the mic on AM only it squeals through my speaker unless I turn it down two 1 which kind if defeats the purpose of having the mic .Why doesn't it do it on SSB ? It doesn't do it with the stock mic , any thought's ? I have not tried changing the patch cord yet but that is new . Thanks !

 

[357magnum]

I forgot to add it only does it with amp on an I checked to see if the braided shield wire might be shorting out with a stray strand do to the fact it an older mic an has been re-soldered a few times .

 

[M0GVZ]

It doesn't do it on SSB because SSB isn't a constant carrier so the power you're outputting is anything from 0 to 100% depending on your voice level. You would find that if you were to whistle into the mic on SSB you'd get the same problem.

 

[357magnum]

Sorry about that M0GVZ I thought about that after I posted .

Sent from my NB09 using Tapatalk

 

[9C1Driver]

If it only does it with the amp on then maybe try a different jumper, move the amp further away from the radio, double check the amp grounding. I assume the radio does not have talkback and nothing has been clipped.

Some times RF does funny things and you just have to chase things down. In the end maybe that mic just won't work.

 

[hotrod]

This is what I have Turner JMU + 2 mic , Cobra 140 GTL an a King Bee 250 ( I think made by Palomar ) when I key the mic on AM only it squeals through my speaker unless I turn it down two 1 which kind if defeats the purpose of having the mic .Why doesn't it do it on SSB ? It doesn't do it with the stock mic , any thought's ? I have not tried changing the patch cord yet but that is new . Thanks !

if turning down mic helps then its just too much audio . id just use a
noise canselling mic of your choice

 

[357magnum]

Thank you I'm going to change the patch cord an the re-do the ground this mic has been a PITA since day one .

 

[dx31353]

I am wondering if your main power bus in your amp has any DC filter caps?

Sent from my SCH-I545 using Tapatalk

 

[loosecannon]

is TR32 cut, clipped, or otherwise modified inside your radio?
what, if any other audio mods have been done.

what is the SWR going IN to the amp? (like, if you were to put an SWR meter in between the radio and the amp)

what is the SWR coming out of the amp?
how close is your station to your antenna?

trying to be "loud" comes with a price.
LC

 

[357magnum]

As far as the radio I ran it as a base for years with no problems with a D104 I never had anything clipped I am starting to think it's the mic itself I hooked up my SSK to the radio an it was fine I didn't have a chance today but I am going to disassemble the plug an see if one of the wires is shorting .I am starting to think it might even be the wiring inside the mic itself due to it's age an when I removed the old Battery there was some corrosion in there but I thought I cleaned it out . It might have done more damage than I thought .

 

[Shockwave]

The key here is the feedback is with the "external" speaker. That indicates the external speaker wire has become a receive antenna for RF. Place a ferrite RFI bead on the speaker wire right at the back of the radio. If that doesn't do it 100% add a .001 uf ceramic disk cap directly across the speaker plug in front of the RFI choke. This assumes the problem is only present with the external speaker and works without feedback on the internal speaker.

 

[357magnum]

I think I found the problem if I " pinch or move " the wire's where the feed into the mic itself it stops . I think it's got a bad wire in the mic wire itself time to ether cut the pc out an re-wire or buy another mic . I think I am going to choose the latter an save this for rainy day project .

 

[hotrod]

I think I found the problem if I " pinch or move " the wire's where the feed into the mic itself it stops . I think it's got a bad wire in the mic wire itself time to ether cut the pc out an re-wire or buy another mic . I think I am going to choose the latter an save this for rainy day project .

i may need just rewired. you may have a loose wire about to fall off