[Amps] Trio TL-922
n4zr at contesting.com
Wed Jun 30 02:26:02 EDT 2004
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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