Hello Ott,
Upon further examination of the two schematics on the
http://youkai.net/tl922/ site, it appears that the power levels are
quite different on CW & SSB for each amplifier. The plate voltage is
1700V @ 500mA for BOTH CW & SSB on the top schematic (Trio..? maybe
Japanese domestic use only..?), but the plate voltage is 2500V @ 800mA
for SSB and 1700V @ 800mA for CW on the lower schematic (export..? USA,
EU, etc..?). Also, on the top schematic, there is no connection to the
transformer BLACK wire, which will reduce the plate voltage by at least
400V.
What are the RF power limits in Japan..? This amplifier was configured
for use in a power-restricted environment.
Also, the 7.5V is different for both schematics. The top schematic
lists 0V for SSB and 7.5V for CW, but the bottom schematic shows 7.5V
for BOTH SSB and CW.
It would appear that your TL922 can be rewired to conform to the lower
schematic and would then be capable of operating at the higher plate
voltage on SSB. On one of the web pages, there is a procedure
illustrating the conversion process. Yes, it's written in Japanese,
but, as a very wise Oriental man once said, "One picture is worth one
thousand words".
Sayonara & 73 Ottsan, Larry - W1GOR
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
On Behalf Of r391
Sent: Tuesday, June 29, 2004 10:59 PM
To: amps@contesting.com
Subject: [Amps] Trio TL-922
Just purchased a "Trio" version of a Kenwood TL-922. Upon getting it
connected I found that the plate voltage did not rise to 3kv as the
operators manual indicated it should when in SSB mode.... thinking
"trouble" I downloaded a copy of the Kenwood service manual.
The service manual like the operators manual, intimated that the plate
voltage should rise to 3kv in SSB mode and this feat is supposed to be
accomplished by using different hv transformer taps but... unlike the
operators manual, the service manual had a very small sentence buried in
the how things work section stating that the mode switch accomplished
its
mode switching by shorting across the zener bias diode when going from
cw
to ssb with no mention of transformer lead switching and yet... both the
service manual schematic and the operators manual schematic are
identical
to each other and neither one showed said shorting out of the zener
diode
and instead showed switching of the transformer leads.
Looking deeper on the net I came across a Japanese only website and
found
the following...
http://youkai.net/tl922/
Wish I could read Japanese... this site would be an interesting read to
be
sure... anyway, the top schematic actually resembles the wiring in my
rig
and the bottom schematic resembles the one in the two manuals.
Questions:
Is 3kv ssb operation the norm for the 922 amp or is 2kv? As I have no
experience with the 922, my amp may be working as Kenwood intended and
I'm
concerned about nothing...
If 3kv is the norm, does the above Japanese link show some kind factory
mod
unique to Japan (like US amps without 10 meters)... perhaps due to some
kind of power restriction or was this mod a way for the factory to
control
the not invented here, parasitic problem?
Do I want to rewire per the operators/service manuals schematics for 3kv
operation or is this a bad idea?
Any help or insight is greatly appreciated.
tnx, Ott
KA3OTT
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