[thinktreasure]

The RCA tube sub. guide for emergency services lists the 25L6 as a sub for a 25A6.  Filament power is the same in both but looks like the 25L6 has more gain.

DC resistance isn't the same as impedance so you can't really say is it's mismatched or not.

http://radiorestorer.com/rcawartubes.PDF

Thanks for the substitution information, I have never seen that.
On the impedance, and the loading on the audio output, when Philco puts 200 ohm's for the speaker coil in their schematic this is not the static resistance of the coil?
What i was questioning was the AK speaker operating on the Philco chassis.


Step 1 will be to get the correct tube it was designed to operate with.

When measuring the cathode bias on the tube this is taken from the B- gnd? at the main filter.
The cathode voltage should be negative, correct?

I have the radio playing and do intend to replace the usual things, caps, out of tolerance resistors, however when the volume is increased it distorts. The signal remains clean at the volume control, and the tube has been tested.


Steve