09-05-2008, 04:43 PM
A couple of things you need to check on those old Philco Transitones. As with all auto sets, the filaments are returned to chassis, generally with a ground lug held by one of the mounting eyelets for the socket. Over all those decades, there is a barrier of corrosion that forms between the grounding lug and the chassis. The filament is no longer grounded, and often does not light. It might be a good idea to make a soldered connection directly on the chassis, and wind a bare wire pigtail to the filament terminal and the solder pool on the chassis.
One other part of the above is that if the connection to chassis is bad on the power amp tube (41 or 42), the cathode and filament pins are tied together, then grounded with that ground lug. Now, if the connection is poor, a whole volt may be measured from the filament (and cathode) pins to ground. The filament is lit OK, but there is virator hash in the output of the set. If you have that bad connection, you are feeding the vibrator hash into the cathode of the tube, and you have a sort of "grounded grid" signal feed into the power amp stage.
Second thing. Check the grid capacitor in the oscillator, and the grid resistor. They could be the source of weak or dead oscillator.
And lastly, don't get bent out of shape over old style vibrators. I'd never send a radio out with a solid sate one.
One other part of the above is that if the connection to chassis is bad on the power amp tube (41 or 42), the cathode and filament pins are tied together, then grounded with that ground lug. Now, if the connection is poor, a whole volt may be measured from the filament (and cathode) pins to ground. The filament is lit OK, but there is virator hash in the output of the set. If you have that bad connection, you are feeding the vibrator hash into the cathode of the tube, and you have a sort of "grounded grid" signal feed into the power amp stage.
Second thing. Check the grid capacitor in the oscillator, and the grid resistor. They could be the source of weak or dead oscillator.
And lastly, don't get bent out of shape over old style vibrators. I'd never send a radio out with a solid sate one.