Browning Mark II feeds

[spongbob]

I have a Browning Mark II radio that feeds while keyed using a banana microphone only.
Any suggestions what the problem could be?

 

[KneeBiter]

Maybe its Hungry??

 

[nomadradio]

If the receiver won't shut off while you're transmitting, I would look for a shorted disc capacitor on the 6AQ5 speaker-amplifier tube.

Do you hear talkback audio in this radio when using other mikes?

Just trying to get a clearer picture of the fault.

73

 

[spongbob]

No talk back audio. On air reports are good with hand PT507-4 microphone.

 

[nomadradio]

So, they're hearing a feedback squeal on your signal, but you don't hear it in the room, right?

Sounds as if maybe the circuit that puts a tone onto the Spot carrier is not shutting off. The DM507 is a low-impedance mike. The banana mike is high impedance. The low-impedance mike may be "shunting" the tone audio to ground. A high-impedance mike would not do that.

Now, this may sound odd, but lay the opening in the front of the banana mike against your ear and see if you hear a faint tone coming out of the mike. It should be the same pitch as the one in your Spot carrier.

Or you could flip it over, remove the bottom cover and see if the tiny glass neon lamp just to the rear of the mike socket is dark when you key the mike, and lights up (dimly) with the Spot button.

If that lamp glows when you key the mike, this is probably the source of the tone. Clipping one leg of the neon lamp would cure this.

73

 

[spongbob]

The light goes out when microphone is keyed,but problem solved. I found a old EV element that I used to put in place of the Heil HC-5 element and problem solved. Thanks guy for all the great information.