[Collins] More on KWM-1 neutralization

[AI2Q]

I'm happy to report that the neutralization of my venerable KWM-1 is now 
complete.  For reference purposes, the PA neutralization was done according 
to the handbook procedure I have used for years on other rigs. My KWM-1 has 
a screen disable slide switch, so removing screen B+ is a snap. To remove 
plate B+ I simply unsoldered the B+ lead at the feedthrough bypass capacitor 
on the bulkhead near the rear-panel power / signal connector.

Once B+ was removed, I peaked the rig's RF output into a 50-ohm dummy load 
using the pi-L controls and exciter tuning. The neutralization cap tweak 
gave a very deep dip on my scope connected across the load.

I did try removing the filament lead from the 6CL6 driver tube, as suggested 
by KØCQ for the 32S-1, but this does not work in the KWM-1, as it disturbs 
the filament distribution for the remainder of the rig. As such, what I did 
was neutralize the driver with the 6146 screens off. It was very easy, at 28 
Mc., to get a deep null from the driver plate neutralization cap.

The so-called feedback neutralization was then accomplished by dipping the 
plate, with full B+ applied and grid drive, then adjusting the feedback cap 
so the grid current dipped at the same point as the plate current dipped. 
Bingo!

Vy 73, AI2Q, Alex
Member: ARRL, FOC, RSGB, CWops, QRP-L, Antique Wireless Association, Wide 
Area Amateur Radio Network
http://home.roadrunner.com/~alexmm