Why Differeny Demodulators/

[benman94]

Originally Posted by Electronic M

Zenith never built their own signal tubes, and ISTR a Zenith film where they touted that demodulator circuit as being their own design. It is quite possible that GE color demod tube existed because Zenith had GE make it for them.

That's the issue though, nobody actually used the 6AR8 in a television set that I've been able to find. It saw some use in ham radio equipment as a product detector, especially as SSB took off, but I don't think it ever saw use in a television set.

Why would Zenith order a tube from GE they weren't going to use?

[KentTeffeteller]

Zenith owned a ham radio manufacturer, Central Electronics, by the way.

[old_tv_nut]

I can't find a spec sheet for Zenith's 6JH8 demod tube, but one site mentions the characteristics being so close to 6AR8 that it's not worth building a separate SPICE model. So, the function must be the same.

Looking at a Zenith schematic and the 6AR8 spec sheet, the 6AR8 and 6JH8 pinouts are the same. Also, the voltages in the Zenith schematic don't exceed the ratings of the 6AR8. So, why a different tube number, I don't know.

[wa2ise]

Originally Posted by old_tv_nut

For companies that developed lots of patents, a patent suit negotiation often went by both parties bringing their stacks of patents, and then "I'll drop one if you'll drop one" - and onward until the company with the fewest had none to trade - and RCA always had the biggest stack.

Back in the 80's, I invented a few patents for RCA at their Smirnoff Labs. And yes, we did "play poker" with the competitors. The Lab;s mission was to generate more "cards" for this "game". It was a great job, until GE raped and pillaged RCA...