It's (almost) back to original circuitry now. The 50K resistor you see
hanging off the chassis is connected to the cathode of the 1st. audio amp.
It doesn't belong there, but the radio will not play properly without it.
With it, the cathode voltage sits around 30 volts. Without it, it sits
around 70 volts, and the resulting grid bias cuts the tube off so far that
there's more signal at the grid than at the plate.

Any suggestions??

--
Say no to institutionalized interference.
Just say NO to HD/IBOC!

That's confusing. Could you post a schematic?

"William Sommerwerck" wrote in message
. ..
That's confusing. Could you post a schematic?

http://www.nostalgiaair.org/PagesByM...8/M0002028.pdf

Hmmm... This is a totally unfamiliar circuit, so I'll limit my ignorant
comments to the following.

Based on what I can figure out, the plate current is 1mA. That should put
the cathode voltage at 60V, not 70V -- which still seems rather high.

I assume you've checked the obvious stuff like the resistor values.

"William Sommerwerck" wrote in message
. ..
Hmmm... This is a totally unfamiliar circuit, so I'll limit my ignorant
comments to the following.

Based on what I can figure out, the plate current is 1mA. That should put
the cathode voltage at 60V, not 70V -- which still seems rather high.

I assume you've checked the obvious stuff like the resistor values.



Indeed I have. In fact, every component but the tube itself in the circuit
is new, as I had to rebuild the power supply, first audio, driver, output,
detector and AGC circuits back to factory design. This one's a puzzle for
me. The voltages on that stage are strange. Plate voltage is quite high,
IIRC, around 240 volts, and the grid is at essentially zero. It's all
supposed to be a part of that squelch circuit, I'm sure.. perhaps it's
staying in the squelched mode for some reason.

"Brenda Ann" wrote in message
...

"William Sommerwerck" wrote in message
. ..

Based on what I can figure out, the plate current is 1mA. That should
put the cathode voltage at 60V, not 70V -- which still seems rather high.
I assume you've checked the obvious stuff like the resistor values.

Indeed I have. In fact, every component but the tube itself in the circuit
is new, as I had to rebuild the power supply, first audio, driver, output,
detector and AGC circuits back to factory design. This one's a puzzle
for me. The voltages on that stage are strange. Plate voltage is quite
high, IIRC, around 240 volts, and the grid is at essentially zero. It's
all
supposed to be a part of that squelch circuit, I'm sure... perhaps it's
staying in the squelched mode for some reason.

I like to say that "science" is not about "facts", but about asking the
right questions. I think you've made the right observation -- the unit is
stuck in squelch mode.

One other possibility... double-check your wiring. (No offense intended.)

Brenda Ann wrote:
It's (almost) back to original circuitry now. The 50K resistor you see
hanging off the chassis is connected to the cathode of the 1st. audio amp.
It doesn't belong there, but the radio will not play properly without it.
With it, the cathode voltage sits around 30 volts. Without it, it sits
around 70 volts, and the resulting grid bias cuts the tube off so far that
there's more signal at the grid than at the plate.

Any suggestions??


Are you checking cathode E to ground? If so, it looks like R24 already
has 35V across it. Add the 50V from R18 to ground, you have 85V to
ground, not counting the E developed across R 15. The voltages given
look wrong, and they don't give a reading for the cathode. I would
select a cathode R to gnd that gave the correct current for good
operation. Ken

"Brenda Ann" wrote in message
...
It's (almost) back to original circuitry now. The 50K resistor you see
hanging off the chassis is connected to the cathode of the 1st. audio amp.
It doesn't belong there, but the radio will not play properly without it.
With it, the cathode voltage sits around 30 volts. Without it, it sits
around 70 volts, and the resulting grid bias cuts the tube off so far that
there's more signal at the grid than at the plate.

Any suggestions??

--
Say no to institutionalized interference.
Just say NO to HD/IBOC!

SAY, I recognize that Pace base unit :-)

Greg
w9gb