Hi everybody,

I've just discover this great site! I'am a electronic technician but I'm newbie in restoration of vintage radio. I've a RCA RF3 AM/FM table radio that loose is channel after 2 hours of playing in AM. It seems that the gain goes to almost zero and if I change the frequency, the radio will be ok for another 2 hours on this channel, but the previous channel never comeback. I change every tube and resistor I found. I don't have this problem in FM mode and the FM RF section is in a shielded area. So I'm puzzled.

Thanks for all

Daniel Trudeau

Hi,
It sounds as if it may be a capacitor breaking down in the Rf amplifier stage. A bad solder joint, or dirty tube socket connection could also be the cause.

If you have a can of "circuit chiller", operate the radio until the channel fades, then spray the capacitors in the RF stage and oscillator/mixer stage of the AM band. The bad component should reveal itself when chilled. If the chiller spray is not available, gently tug at the ends of the tubular cpacitors; you may find one that comes apart with the most gentle touch (if this is done while the radio is operating, be sure to use a non-conductive stick, or insulated screwdriver.

: Hi everybody,

: I've just discover this great site! I'am a electronic technician but I'm newbie in restoration of vintage radio. I've a RCA RF3 AM/FM table radio that loose is channel after 2 hours of playing in AM. It seems that the gain goes to almost zero and if I change the frequency, the radio will be ok for another 2 hours on this channel, but the previous channel never comeback. I change every tube and resistor I found. I don't have this problem in FM mode and the FM RF section is in a shielded area. So I'm puzzled.

: Thanks for all

: Daniel Trudeau