03-15-2013, 08:38 PM
Some of you may have watched previous problems with this chassis of a friend of mine. It works like a champ, at least it did for quite some time. Dead now from a station standpoint. I can shove an IF signal through it. Seems the problem is in the front end. On my scope, I can see the output of the RF amp and when on station, looks good. After that things go down hill. Did some voltage measurements of the oscillator area and it is no wonder why it went deaf.
RF tube 6K7G, good on all voltages.
Mixer tube 6Ag8G measures well on all pins
Oscillator tube, 6A8G Pin 3 should be 290V, measures 0 Pin 4 should be 90V measures 60
Pin 6 should be 225V measures 0
Osc Control 6Sn6G Pin 3 should be 225V measures 0
Pin 6 should be 225V measures 0
Would seem to me somewhere a voltage source just ain't hacking it. Any ideas?
Schematic link:
http://www.nostalgiaair.org/Resources/235/M0013235.htm
RF tube 6K7G, good on all voltages.
Mixer tube 6Ag8G measures well on all pins
Oscillator tube, 6A8G Pin 3 should be 290V, measures 0 Pin 4 should be 90V measures 60
Pin 6 should be 225V measures 0
Osc Control 6Sn6G Pin 3 should be 225V measures 0
Pin 6 should be 225V measures 0
Would seem to me somewhere a voltage source just ain't hacking it. Any ideas?
Schematic link:
http://www.nostalgiaair.org/Resources/235/M0013235.htm
A friend in need is a pest! Bill Slee ca 1970.
