Re: [Amps] Trio TL-922

[Pete Smith <n4zr@contesting.com>]

Ott, shorting across the zener diode affects the cathode bias and hence the 
resting plate current (with no drive), not the plate voltage.

I looked at the site you mentioned -- I read some Chinese, which made it 
possible to fake my way through enough to understand what is 
happening.  The a) schematic shows the domestic variant of the amplifier, 
and states that it is rated at 1700 volts at 500 ma in both CW and SSB 
modes.  The CW/SSB switch serves only to change the bias from 7.5 volts on 
CW to 0 volts on SSB, presumably for better linearity.  The b) schematic is 
the export model, and a note states that it produces 2500 volts at 800 ma. 
in SSB position, and 1700 volts at 800 ma. in CW position, with 7.5 volts 
bias in both modes.  That's consistent with the schematic.

It appears to me (and this is right at the limits of my faking ability) 
that the 4th and 5th links on the left side of the page walk you through 
the process of modifying the domestic version to the export spec.  Looks 
pretty simple, assuming the transformers are identical -- maybe somebody on 
the reflector *really* reads Japanese and can tell you if there are any 
cautionary notes.  I tried Babelfish at world.altavista.com for a machine 
translation, but it couldn't handle the web page, which uses an unusual way 
of linking to subordinate pages that apparently crossed it up.

73, Pete N4ZR 

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