[Amps] Trio TL-922

r391 r391 at worldnet.att.net
Tue Jun 29 22:59:12 EDT 2004

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...


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.


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

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