Drake TR-4C -- need advice -- PTT not working
 

I recently bought a Drake TR-4C / RV-4C / AC-4 station
which came from an estate. The gear is nice and clean
and appears to be 100% stock.

After I rebuilt the power supply and replaced a couple
of tubes, the station is operational with the exception
that I have no push-to-talk (PTT). VOX works fine on CW
and SSB. I replaced the 6EV7 tube, and that didn't help.
I tried two different microphones and got the same result
with both of them. Both mics work fine with my B-Line,
so it's not a mic wiring or switching problem. Before I
dive in with a voltmeter, does anyone have any suggestions
on what may be wrong, perhaps based on personal experience?
And yes, I'm aware that the CW key must either be closed
or unplugged for PTT to function.

Thanks and 73,
Dean K5DH

In article ,
K5DH wrote:
I recently bought a Drake TR-4C / RV-4C / AC-4 station
which came from an estate. The gear is nice and clean
and appears to be 100% stock.

After I rebuilt the power supply and replaced a couple
of tubes, the station is operational with the exception
that I have no push-to-talk (PTT). VOX works fine on CW
and SSB. I replaced the 6EV7 tube, and that didn't help.
I tried two different microphones and got the same result
with both of them. Both mics work fine with my B-Line,
so it's not a mic wiring or switching problem. Before I
dive in with a voltmeter, does anyone have any suggestions
on what may be wrong, perhaps based on personal experience?
And yes, I'm aware that the CW key must either be closed
or unplugged for PTT to function.

If you are set for SSB operation and plug a key in, does closing the key
transmit?

I would start looking at the CW key jack and the microphone jack and
the associated wiring.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article , says...

In article ,
K5DH wrote:
I recently bought a Drake TR-4C / RV-4C / AC-4 station
which came from an estate. The gear is nice and clean
and appears to be 100% stock.

After I rebuilt the power supply and replaced a couple
of tubes, the station is operational with the exception
that I have no push-to-talk (PTT). VOX works fine on CW
and SSB. I replaced the 6EV7 tube, and that didn't help.
I tried two different microphones and got the same result
with both of them. Both mics work fine with my B-Line,
so it's not a mic wiring or switching problem. Before I
dive in with a voltmeter, does anyone have any suggestions
on what may be wrong, perhaps based on personal experience?
And yes, I'm aware that the CW key must either be closed
or unplugged for PTT to function.


If you are set for SSB operation and plug a key in, does
closing the key transmit?


Nope. Closing the key yields a momentary click of the T/R
relay and that's it.


I would start looking at the CW key jack and the microphone
jack and the associated wiring.
--scott

Already looked at the wiring. Didn't see anything wrong with
it. No evidence it's ever been tampered with, either.

Dean

On Fri, 09 Jul 2004 15:15:39 GMT, (K5DH) wrote:

I recently bought a Drake TR-4C / RV-4C / AC-4 station
which came from an estate. The gear is nice and clean
and appears to be 100% stock.

After I rebuilt the power supply and replaced a couple
of tubes, the station is operational with the exception
that I have no push-to-talk (PTT). VOX works fine on CW
and SSB. I replaced the 6EV7 tube, and that didn't help.
I tried two different microphones and got the same result
with both of them. Both mics work fine with my B-Line,
so it's not a mic wiring or switching problem. Before I
dive in with a voltmeter, does anyone have any suggestions
on what may be wrong, perhaps based on personal experience?
And yes, I'm aware that the CW key must either be closed
or unplugged for PTT to function.

Thanks and 73,
Dean K5DH


Dean,

Have you replaced the 6FQ7? This tube controls the TX/RX.

Walt, KA2NJF

In article ,
says...

On Fri, 09 Jul 2004 15:15:39 GMT, (K5DH) wrote:

I recently bought a Drake TR-4C / RV-4C / AC-4 station
which came from an estate. The gear is nice and clean
and appears to be 100% stock.

After I rebuilt the power supply and replaced a couple
of tubes, the station is operational with the exception
that I have no push-to-talk (PTT). VOX works fine on CW
and SSB. I replaced the 6EV7 tube, and that didn't help.
I tried two different microphones and got the same result
with both of them. Both mics work fine with my B-Line,
so it's not a mic wiring or switching problem. Before I
dive in with a voltmeter, does anyone have any suggestions
on what may be wrong, perhaps based on personal experience?
And yes, I'm aware that the CW key must either be closed
or unplugged for PTT to function.

Thanks and 73,
Dean K5DH


Dean,

Have you replaced the 6FQ7? This tube controls the TX/RX.

Walt, KA2NJF


Hi Walt,

The TR-4C uses a 6EV7 instead of the 6FQ7 used in the
earlier models. Thanks for the help attempt! :)

73,
Dean K5DH