[Collins] KWS-1

[Glen Zook]

Unless one is operating in a contest, or often when working rare DX, the 200 Hz CW filter is definitely hard on the ears.  In the 75S-3 / 75S-3A manual, the suggestion is made to use the variable BFO to lower the tone frequency.  In my 75S-3A I added the 455.800 kHz BFO crystal, like in the 75S-1 / 75S-2 when the 500 Hz mechanical filter is added, to get the CW tone frequency to a more reasonable frequency.  Of course, I can still use the variable BFO with any of the filters.

I can still remember the "goode olde dayes" when selectivity in a goodly number of receivers had to improve to even make the dismal level.  As such, most of the time, I just use the stock 2.1 kHz filter when operating CW.  The 500 Hz mechanical filter that is in one of my 75S-1 receivers is a definitely an excellent compromise between the 200 Hz and 2.1 kHz filters when operating CW.

The rejection tuning in the 75S-3- series works very well.  I added the Waters kit to one of my 75S-1 receivers and that helps with eliminating QRM.

Glen, K9STH


On Sunday, July 6, 2014 11:20 PM, Dr. Gerald N. Johnson <geraldj at netins.net> wrote:
 




On 7/6/2014 3:30 PM, Glen Zook wrote:
> As far as I can determine, there were never any advertisements for
> the KWS-1 or 32W-1 as kits.  Collins was not in the business of
> selling kits.  Art Collins was not going to put the Collins name on
> something over which he didn't have absolute control in the
> assembly.

I just checked the 1955 ARRL handbook and it doesn't mention kits. It 
does say the factory can convert at 32W-1 to a 30L-1.
>
> However, several Collins employees were able to obtain, at the
> Collins Cedar Rapids surplus store, enough parts and assemblies to
> build a 75A-4 and, probably, a few persons obtained enough parts to
> build a KWS-1 or 32W-1.

That was true for S-line too and we could buy stock room and warehouse 
parts for cash at the engineering parts booth in Cedar Rapids. Long 
about late '63 they stopped selling PTOs that way and insisted the only 
way to buy a PTO was in a 312B-5 for a lot more money and that slowed 
the home made S-line and KWM-2 construction projects.
>
> Since the amateur radio equipment was built in the Cedar Rapids area
> (there were some 75A-4 receivers made at the Collins facilities in
> Toronto and some KWM-2- series made in Japan under license) I never
> saw any assemblies for the amateur radio line at the Collins surplus
> store next to Building 427 which was located about 2-miles south of
> the Richardson city limits actually within the City of Dallas.

I never saw much there but microwave parts the year or so I was in Texas.
>
> Art had some quirky ideas with the amateur radio equipment.  He
> declared that no 75S-1 or 75S-2 receivers were to be shipped with the
> optional 500 Hz mechanical filter and the optional BFO crystal
> installed.  Instead, one had to purchase the receiver from a dealer
> and then return the receiver to the factory or approved service
> facility to have the items installed.  Or, the filter and crystal
> could be purchased and installed by the owner of the receiver.
>
> I actually have what is probably the only 75S-1 that was shipped,
> from the factory, with the filter and crystal already installed.
> However, that receiver cost a Collins employee his job!  The employee
> purchased the 75S-1 through the employee purchase program which made
> the equipment considerably lower in price than "retail".  The
> employee "knew" someone at the factory and made arrangements to have
> the CW filter and optional BFO crystal installed.  Within a few days
> of receiving the 75S-1, Art "found out" about the receiver and called
> the employee into his office.  When confronted with the fact that, by
> having the filter and crystal installed, and not wanting to
> experience of the wrath of Art, the employee immediately quit his
> job.
>
> After quitting, the employee immediately sold the 75S-1 to another
> amateur radio operator who lived in the Dallas suburb of Garland,
> Texas.  That person already had a 75S-1 and put the receiver in his
> garage where it sat for over 40-years!  Then, the receiver was traded
> to another amateur radio operator, who lived east of Dallas in
> Terrell, Texas, for some closed circuit television equipment.  The
> new owner then traded me the 75S-1, and several other pieces of
> equipment, plus some cash, for an Aerotron 450 MHz FM repeater that I
> had retired from commercial two-way use.  I had no idea that the CW
> filter was installed until I put the receiver on the test bench to
> check it out.  I mentioned to the person from which I had obtained
> the receiver about the CW filter.  He then checked with the person
> who had traded the receiver for the television equipment.  That
> person related the story about the purchaser losing his job with
> Collins Radio Company.
>
> The receiver has the quality assurance glyptol on the various
> connections where the filter is concerned and those marks are exactly
> the same as the original wiring in the receiver.
>
> Basically, I obtained a new 75S-1 receiver over 40-years after it had
> been manufactured.
>
> Then, with the 75S-3 and 75S-3A, Art insisted that EVERY receiver was
> shipped with the 200 Hz CW filter installed.  When the 75S-3B and
> 75S-3C receivers came out, Art changed his mind again and those
> receivers did not come with the CW filter installed.  Instead, the CW
> filter was an expensive accessory.

The S-3B/C the filters were plug in. No wiring required. I found a bug 
in my new S-3B (May 1964), the magnetic field from the power transformer 
modulated the mechanical filter making noise had a hum component. That 
was with the plastic FA case filter. I had a sample of mu metal which I 
bent to fit the filter and that has solved that problem ever since. The 
Cedar Rapids solution was to fabricate a steel cover, trouble was the 
200 Hz CW filter was taller than that magnetic shield. I had that filter 
and didn't like it. I haven't seen it lately so I guess I sold it. It 
was too narrow and ringy like that vintage SSB filter but worse because 
of it being so narrow.
>
> Glen, K9STH
>
I still prefer a 2.1 SSB filter for CW unless the QRM is really bad like 
FD, otherwise I want to know what's going on around the signal I want to 
copy. I do have 500 Hz CW filters in a couple of my modern radios.

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

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