[Collins] KWM-1 neutralization procedure

[Dr. Gerald N. Johnson]

That is a good technique. If you leave a path for screen or plate 
current your dip will not be exact neutralization. You have to 
disconnect those supply lines from the driver to neutralize it. I'm not 
so sure about the feedback neutralization. There is a procedure in the 
KWM-1 manual using signal generator and detector. And on the detector 
schematic I see the draftsman missed a digit on his Leroy lettering kit 
and calls for a 60 microamp meter that was never made, better to use a 
50 microamp meter, they can be bought without having it made special. 
Just like the schematic for wattmeters shows a 390 microamp meter when 
it was really 300 microamps.

Now compare the KWM-1 manual technique to that in the 32S-1 manual which 
uses transmitted signal with plate and screen disconnected (and there 
the driver neutralization will work better with both plate and screen of 
the driver tube disconnected, opening the screen alone lets there be a 
little tube gain yet) and then neutralizes the feedback so that plate 
and grid current dips coincide as you tune the pat plate tuning. Without 
checking, I think that the transmitter circuits of the KWM-1 and 32S are 
very similar so the neutralization should work well with either manual 
technique.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 5/21/2011 12:16 PM, AI2Q wrote:
> What is the best way to neutralize the (a) driver, (b) feedback trimmer,
> and (c) PA of my KWM-1?
>
> My late model KWM-1 has a screen-off slide switch as well as an RCA
> phono socket on the chassis for the grid.
>
> I am used to neutralizing by removing B+ from plates and screens,
> applying drive, and adjusting for minimum output on my scope placed
> across (a 50-ohm load) after peaking the pi-L network on the 6146s.
>
> Any help or suggestions appreciated.
>
> Vy 73, AI2Q, Alex
> Member: ARRL, FOC, RSGB, CWops, QRP-L, Antique Wireless Association,
> Wide Area Amateur Radio Network
> http://home.roadrunner.com/~alexmm
>