David,

I am using T-29 as the VFO. That goes into the resistor slider tuned network (low Q) (see the picture) which provides an 18 ohm load for the T-29. Since a wire wound resistor has both resistance and inductive reactance I simply resonated the slider resistor with a capacitor to form a parallel tuned circuit. The slider on the resistor is connected to the grid of the first 211 tube which then makes it a buffer amplifier to feed the PA second 211. I broke the connection to the first 211 where it receives feedback through a capacitor for the PA with the first 211 was acting as an oscillator. Driving with 30W from the T-29 I get about 85 watts out of the BC-375.

The audio is being driven through a small mixer with equalizer into the the standard mic input on the BC-375. I did remove the internal carbon mic bias inside the BC-375.

Behind the control panel is a relay to key the T-29 and mute the BC-348. Also is the small mixer. The relay is keyed by the BC-375.

These two changes (the only two I made) are very easily reversible in less than 30 minutes.  

Let me know if you have other questions or would like to see a schematic of the input circuit.

73,

Mack
W4AX

On Sun, Nov 13, 2022 at 15:43 David Stinson <arc5@ix.netcom.com> wrote:
Wow!  That's some lovely work.
Please give us details on how you're feeding
drive to the MO stage, and how you are driving
the audio.  Excellent, good sir.

On 11/13/2022 2:00 PM, Mack McCormick wrote:
> The transmitter and tuning units were located new in the box from the GE
> factory in 1934. I’m using a T-29 transmitter as a VFO to prevent the
> BC-375 from FM’ing due to using a MOPA oscillator. I built the custom
> furniture with inspiration from the Western Historic Radio Museum. I
> have about 120 hours into this project and it is working perfectly! I
> plan to have it on the Old Military Radio Net next Saturday.
>
> https://photos.app.goo.gl/iyYRv1cEQafeCrrj7
> <https://photos.app.goo.gl/iyYRv1cEQafeCrrj7>
>
> 73,
>
> Mack
> W4AX
>
> --
> 73,
>
> Mack
> W4AX
> https://www.qrz.com/db/w4ax <https://www.qrz.com/db/w4ax>
>
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73,

Mack
W4AX
https://www.qrz.com/db/w4ax