[SignalOne] Color Me Stupid...

[wes Bolin]

I have my CX7A back on the air again....this was a battle for me.

Found my problem.  To restate it, when the Time Delay Relay timed in, the
S-meter would go well over S-9 in white noise and the heatsink would get
very hot. I have learned a lot about T/R switching, and PA Bias, and what
would make the Noise go away.  It
turns out I have a stuck contact, E5, inside the Reed Relay.   I have
cobbled around it by connecting the bias control lead from the Solid State
Driver board (377) to a 33ohm resistor to the RLY contact on rear chassis.
It is grounded in PTT, and the radio is transmitting and
receiving like it should again.  Final fix will be a small relay added
inside the chassis. The original relays are probably unobtanium.

Hope it is back in its cabinet soon.

On Wed, Nov 20, 2024 at 4:50 PM parinc1 <parinc1 at frontier.com> wrote:

>
>
> This list is for discussions regarding collecting, repair, use and sale of
> Signal/One radios and accessories.
>
> Documentation on Signal/One radios can be found at
> http://www.hamanuals.com and several other sites on the Web.
>
> .
> Congrats Jerry,
> Another CX-7 made operational. I would think the keyer may be the simplest
> of all the issues you have found. Hope I am not jinxing you.
> Dale W4OP
> ________________________________
> From: signalone-bounces at mailman.qth.net <signalone-bounces at mailman.qth.net>
> on behalf of jerry <jerry at tr2.com>
> Sent: Wednesday, November 20, 2024 2:39 PM
> To: Signalone <signalone at mailman.qth.net>; Signal One <
> signal-one at groups.io>
> Subject: [SignalOne] Color Me Stupid...
>
>
>
> This list is for discussions regarding collecting, repair, use and sale of
> Signal/One radios and accessories.
>
> Documentation on Signal/One radios can be found at
> http://www.hamanuals.com and several other sites on the Web.
>
> .
> Having gotten SSB transmit working, I turned my attention to CW.  By
> voltage measurements, I had found a bad
> NPN bipolar transistor that tells the MOSFET audio switch to pass the
> sidetone.
>
> That transistor turned out to be Q7 in....
>
> ...can you guess it? ....
>
> ...THE RF DRIVER BOARD...
>
> Which I had just reinstalled :).
>
> I *knew* which transistor it was, and I *knew* which board it was on
>
> ...But I had forgotten.
>
> OK, let's schlep that board out yet again.
>
> Replaced the transistor with a 2N3904.
>
> Now CW works fine with a hand key.  The keyer is for some reason INOP.
> Even though it used to work.
>
> Well, as I always used to say "Everything works until it stops working".
>   There's a story behind that.
> Maybe some other time.
>
>                   - Jerry, KF6VB
>
>
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