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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 19th Jul 2017, 2:58 am   #21
Synchrodyne
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Default Re: Lesson R,L,C,T,V,D but Q and U ?

Possibly Toshiba used "S" for silicon-based device? But if so, we might also expect to find "G" for germanium.

In the early Sony case, I imagine that "X" was for Xtal = crystal triode.

Cheers,
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Old 19th Jul 2017, 4:12 am   #22
turretslug
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Default Re: Lesson R,L,C,T,V,D but Q and U ?

S for Semiconductor? In the thermionic era, "V" included diodes, so perhaps an updated counterpart seemed apposite.
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Old 19th Jul 2017, 10:38 pm   #23
Synchrodyne
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Default Re: Lesson R,L,C,T,V,D but Q and U ?

Ah yes, “S” for semiconductor seems more logical than “S” for silicon.

So far, the above-mentioned Lin quasi-complementary article remains the earliest I can find where transistors are designated with “Q”. Thereafter “Electronics” magazine often used “Q”, but not exclusively so, sometimes using “T”. Some RCA publications after that date also used “T”. So, there do not appear to have been editorial decisions by “Electronics” or RCA to standardize on “Q”.

Possibly it came from RETMA or the US Military, as one imagines that the latter would want to have standardized schematics. Or as a “left-field” idea, perhaps it was simply caprice on Lin’s part, taking the “Q” from quasi, with others then following what seemed like a good idea.

But then I’m thinking that when the answer does turn up, it will be “none of the above”.

The Lin quasi-complementary circuit was certainly a landmark, although I am not sure that it was intended as such, but more as another approach, and as part of a complete gramophone amplifier. Fully complementary circuits had been proposed several years earlier. It’s interesting too that improvements to the Lin circuit to correct its inherent asymmetry were not developed until the end of the 1960s; of these the Baxandall diode was the definitive version.

Notwithstanding the widespread use of “Q” in American practice, one does find variations. Here is an odd case from an early 1970s Sylvania TV receiver, in which “Q” was used for the VHF tuner, but “T” for the UHF tuner. (The main chassis used “Q”.):

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Possibly the UHF tuner was outsourced from an assembly maker who preferred to use “T” rather than “Q”, and Sylvania opted not to transcribe the schematic, but then they do appear to have been designed to work with each other. They were early varicap units. Thus, one sees an RF amplifier in the UHF tuner, hitherto very unusual in American practice, but probably added to offset varicap losses. The VHF tuner was “transitional”, with a fet RF amplifier but a bipolar cascode mixer, a stepping stone to all-fet designs. Apparently with varicap tuning it was more convenient to inject IF from the UHF tuner into the VHF mixer rather than into the VHF RF amplifier as had been past American practice, so more gain was required from the UHF tuner, in this case obtained by the use of an active mixer in place of the customary diode. (Other makers kept the diode and added an IF stage within the tuner.)

Cheers,
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