Ever wanted to build a tube Video modulator?: the Custom Electronics corp model 3A

[wa2ise]

Originally Posted by Electronic M

All that it could use is an audio modulator section....I'm open to ideas on how to implement it. I initially thought the two tied together inputs may have been for a separate audio modulator that would mix with the video, but that seems unlikely considering that they used to daisy chain many devices along some video lines back then, and the dual input jacks are likely for that rather than two different input devices.

I'd use a 4.5MHz FM modulator and sum that with the video at the 6AS6 grid. It's like an intercarrier scheme, and a benefit is that if the channel frequency oscillator drifts, the sound carrier will follow it.

You could disconnect the 2nd video input jack and use that for the audio input.

[Jon A.]

Originally Posted by wa2ise

I'd use a 4.5MHz FM modulator and sum that with the video at the 6AS6 grid. It's like an intercarrier scheme, and a benefit is that if the channel frequency oscillator drifts, the sound carrier will follow it.

You could disconnect the 2nd video input jack and use that for the audio input.

You have such in-depth electronics knowledge that I actually find such posts of yours a little amusing, not sure why. I say that with all due respect.

[Electronic M]

Originally Posted by wa2ise

I'd use a 4.5MHz FM modulator and sum that with the video at the 6AS6 grid. It's like an intercarrier scheme, and a benefit is that if the channel frequency oscillator drifts, the sound carrier will follow it.

You could disconnect the 2nd video input jack and use that for the audio input.

I like that idea. I'm going to try to use this circuit altered to run at 4.5Mhz. I'm going to build a small sub chassis to bolt in above deck under the top cover so as to make my work easily reversible.


I've already tested the osc. section without the biasing resistor network or 27pF cap (just an all out basic Hartley osc.).