A couple of problems caused the no output issue. There was an obscure wire breakage at a capacitor terminal that was part of the detector cathode circuit. The detector screen bypass cap was also a near short.

I had to manually ground the output cathode resistor because I didn't have the Transmitter box hooked up to complete the connection.

The other caps are unacceptably leaky as well.

The 2 X.1 caps along the side LOOKED like they might be oil, but CD48678 is called out as paper in the manual. Sure enough! They were even more leaky than the group down the center row.

I'm in the process of recapping. I'm leaving the disconnected surface cans in in place and am using the original terminal strip to attach the new caps.

I may want to take you up on the coil offer, once I get this rig running right.

Jim

On Thursday, October 20, 2022 at 09:27:39 AM EDT, David Stinson <[email protected]> wrote:

P.S. IIRC, there's an oil-filled cap on the output of
the audio amp. It goes open a lot and will kill your audio.
I *think* it's in that passive audio filter. No time to
look at the diagram right now. Hope I'm thinking of
the right set.

On 10/19/2022 1:31 AM, Hubert Miller wrote:
>> I'm restoring this system with the original dyno, junction box, control box..
> I built the cables , hooked it up , but the audio is extremely low and I think the TRF stage or stages may be breaking into oscillation.
> I haven't done any real troubleshooting, but I know the dyno module is OK.
> TRF radios can be finicky, so i was wondering if there were any hints as to what to expect ?
>
> I think I'd stuff in a BC band coil and see what it does on an AM local. You can also skip any RF stage by touching a short wire antenna
> to the top of the tuned circuit of the detector stage. Testing the tubes of course is the first step, or at least being certain they are good.
> If a stage is oscillating, you may see very strange voltage on the plate of the tube, even with just a voltmeter.
> A buzzer-injector signal to the plate of the detector tube should tell you if the audio stage is working.
> Good luck - I'm sure you will whip it into shape soon.
> -Hue Miller
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[email protected]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: https://www.qsl.net/donate.html

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com

______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]

This list hosted by: http://www.qsl.net
Please help support this email list: https://www.qsl.net/donate.html