Was Re: [Collins] KWM-2 now black beauty

[kwylow zinjanthropus]

After taking a look at some of the various pieces of gear of yore, you'd think that Collins would be the exception to the rule and leave out those horrible excuses for a capacitor. From what I read about Art Collins' approach to quality control, you'd almost think that he or his fellow collegues would examine every component (with mil spec standards in mind) to bear anathema to such a component and go for something like a Vitamin Q or more quality minded cap. Any suggestions as to how Collins might have slipped the gears on this one? Just my minor opinion. Cal, N6KYR. 
 "Dr. Gerald N. Johnson, electrical engineer" <geraldj@isunet.net> wrote:Likely the VOX time constant capacitor is leaky. If its still a black
beauty it IS leaky. You might try lowering the anti-vox gain, that
should lengthen the VOX delay also.

In my schematic, C 47, C48 and C188 contribute to VOX time constants.
Leakage in any will shorten the VOX delay. I don't see a VOX delay pot,
but that may just mean my schematic is old.

Its the nature of the radio to transmit with a high audio tone. CW is
generated by sending a tone through the audio chain and the audio
frequency is chosen so that only the fundamental passes through the
mechanical filter. If an 800 Hz tone was used, there would be two or
three CW signals at 800 Hz spacing. When the 1600+ Hz tone is used the
filter prevents the audio harmonics from causing multiple carrier
outputs. The key controls the second audio and the second transmit
mixer.

There have been mods, mostly (as I recall) involving adding an effective
RIT to the PTO (already present in the form of the sideband calibration
correction shift) to allow the receiver to listen up about 800 Hz. I
don't have any of those details.

73, Jerry, K0CQ, Technical Advisor to the CRA
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
Sponsored by the Collins Radio Association
http://www.collinsra.com


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