[Kenwood] TL 922A Tune Up

[VA3DG]

Jim - K8ARY wrote:-

> In the CW mode of the manual, Step 6 of the procedure states: "Quickly
switch the amplifier to lp and dip the plate". There is no "lp" meter
position. There is the IP meter, however that appears to be reading plate
current all the time.

 Jim....
    I don't have a TL-922A amplifier, but I do have a Heath SB-200 amp. As
with any tube amplifier, the tuning procedure would be about the same. I
suspect the lp meter you mention above is actually an ip (IP) meter. IP is
an abbreviation for Plate Current, (I=current;P=plate) which is what you
should be concerned about dipping. The idea is to obtain as much RF output
with as little plate current (IP) as possible. As you dip the IP, you should
see an increase in RF output. This is bringing the tube(s) into resonance.
This also works easiest into a dummy load as it's an almost perfectly
resistive load, and you won't bother anybody on frequency!

> My thought is to leave the meter in the RF position to dip the plate and
adjusting for maximum output.  What is the correct procedure?

    This is basically the same as doing what I suggested above. The end
result will be the same...lowest possible plate current for highest RF
output.
>
> I would also be interested in dos and don'ts for this amp.

    While doing the dipping and loading of the tube(s), it's best to use the
least amount of drive from the exciter as you're dipping and loading the
final, and gradually increase the drive to the amplifier.
Sounds like a lot, but it really goes quite quickly once you've done it a
few times...usually takes less than a minute.

Hope the info helps...
Cheers....
Darrell
VA3DG/VE3DDG