[Collins] NB for KWM-2A

[K2QDE]

Michael,

The Collins 136B-2 Noise Blanker for the KWM-2/2A is nothing more than a
TRF, not a super heterodyne, receiver for 40 MHz. It amplifies 40MHz
ignition noise pulses, prevalent during the '50's and '60's before
electronic ignition systems. It requires a separate, 40MHz vertical antenna
(produce back then by NewTronics who sold a custom, 40MHz spiral-wound
wip strictly for its use). I used one in my dad's '58 and it did a great 
job. It
received, amplified, and provided a gating pulse which opened and closed the
receiver IF "blanking" the receiver during each pulse. Ignition noise just
disappeared. The replacement RF Gain was piggy-back to the receiver's RF
Gain in order to provide a gating threshold adjustment to prevent audio
distortion. Unfortunately, the blanker was never effective on any HF,
atmospheric, or other cosmic noise sources. Collins provided it for mobile
users at that time. Problem today is with the four 6U8's filament current
demand on the power supply and the internal heat the unit generated. I did
find useful during Field Day '64 considering the generator we were using.

Should you need this info, the additional parts supplied with the 'B-2 are
Black pointer knob w/setscrew: 544-3090-002
Bushing (shaft reducer, 1/4" to 1/8th" shaft): 545-3091-002
NB RF Gain knob (Clear Plastic): 545-3090-002
Dual RF Gain pot: 376-2147-000

Find a manual and you'll note the Alignment, additional wiring, and the
antenna run are all within the harness. Lastly, don't forget the jumper wire
across J22 and J23. It must be removed when installing the unit.

Stu, k2qde


----- Original Message ----- 
From: "Michael Raskin" <rask1553 at bellsouth.net>
To: "Collins Reflector" <collins at mailman.qth.net>
Sent: Friday, October 28, 2005 10:05 PM
Subject: [Collins] NB for KWM-2A


> Hi all - Just picked up a NB for my KWM-2A.  I would like to find out 
> where I can get any info on the unit.
>
> Mike, W4UM (ex-K4KUZ)  w4um at arrl.net
> South Florida DX Association  http://www.qsl.net/k4fk/
> Florida Contest Group  http://www.floridacontestgroup.org
>
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