[Amps] 756P3 + TL 922A

Vic K2VCO k2vco.vic at gmail.com
Mon Sep 19 20:06:14 PDT 2011

1) Vacuum relay (or similar) QSK is a necessity, even if you are an SSB operator who uses 
VOX or a CW operator who never uses full QSK. The 922 is /designed/ to hot-switch the t/r 
relay in those situations and this is probably the reason for many bandswitch failures.

2) Glitch resistor. I used 15 ohms 20w.

3) Ground the grids directly. I put a copper strap from each grid terminal to the nearest 
ground terminal. Mine is very stable on all bands. W8JI is very persuasive about this. I 
can get 1350 watts on most bands, and could get more with more drive, within the ratings 
of the 3-500Z's (this may be a bit much for the PS, so I don't normally push it this hard).

4) Check the filament voltage! Mine was 5.25V. I put a 15 ohm resistor in series with the 
filament transformer primary. I get about 4.95V now. This also reduces the voltage on the 
meter lamps a bit, making them last longer.

5) I added a soft-start. It may help protect the power switch.

I did NOT change the parasitic suppressors!

On 9/19/2011 12:52 PM, sdunlavey at optimum.net wrote:
> hello.... i am getting the 922a upgraded (mods) ...  other then the mods that are most common.... is there anything else that i should get done to make her run better...?
> Scott D
> www.qsysociety.org
> "do you hear the dits"
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> Amps at contesting.com
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Vic, K2VCO
Fresno CA

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