What's going on?

[Spacecadetje]

I have a General AP Hill radio that is about 18 years old. Recently when someone near me keys up my meter needle is buried to the right and I can't hear them until I key my mic and "reset" it. I've had it happen while turing down the recieve gain too. It has only been happening for a couple weeks. It happens with a magnet mounted generic whip antenna and with a 3' firestick and 18' of cable. Anyone heard of the before? It's installed in a 2014 Volvo.... Thanks in advance for any help.

 

[Tallman]

You must be very close to the other transmitter. Try turning down your RF gain.
You might also have a bad pot on your rf gain.

 

[Spacecadetje]

You must be very close to the other transmitter. Try turning down your RF gain.
You might also have a bad pot on your rf gain.

Thats the thing, I never had problems until about 2 weeks ago..... I'll flip the switch to low and try that. Thanks

 

[9C1Driver]

Sounds like someone with a fair amount of power is keying up very close to you. Usually happens in a truck stop when a driver thinks he needs 500 watts to talk to the truck 80 feet from him. If your in the truck next to his mirror to mirror your receive is getting hammered.

 

[357]

try with the coax off it next time he's on.
dont key up for more than 1 second.
maybe he popped the detection diodes?

 

[Spacecadetje]

Sounds like someone with a fair amount of power is keying up very close to you. Usually happens in a truck stop when a driver thinks he needs 500 watts to talk to the truck 80 feet from him. If your in the truck next to his mirror to mirror your receive is getting hammered.

Yeah but it never happened until about 2 weeks ago. Nothings changed with my set up. Could it be the radio is old and crapping out?

 

[Shadetree Mechanic]

Almost sounds like the receive is going into oscillation. But I really don't know if that's even possible.

 

[Tallman]

Almost sounds like the receive is going into oscillation. But I really don't know if that's even possible.

Yes it is. Any electronic device that is setup to amplify signals can go into oscillation.
You have heard the feed back squeal from a Public Address system? That is an oscillation because the audio from the speaker is getting amplified. It is a feedback loop.

 

[Tallman]

try with the coax off it next time he's on.
dont key up for more than 1 second.
maybe he popped the detection diodes?

If the antenna is disconnected DO NOT key up the transmitter!
It might be the AGC diodes which provide feed back to the receiver amplifier stages.
Feed back can be either positive or negative, AGC is a negative feed back.