[Collins] parts 32S-2

[Dr. Gerald N. Johnson, electrical engineer]

According to my manuals, the 32S1/2 used a 526-9337-00 filter with model
number F455Y21. The Y case was just over a cm diameter (brass) with
solder terminals out the ends. The 32S3 used a 526-9427-00 filter, the
same as the 75S3. A rectangular plastic case F455FA21, made to plug in,
though in the 32S3 its soldered in. It is a little larger, about 1.5 cm
square, so it won't pass through the same shield hole that a Y case
filter fits through. Electrically it is the same.

I don't know what the description of the 278 family of filters is. Its
not on the internet, nor in Collins literature that I can find.

In general Collins product assembly drawings began with 52x, sometimes
5xx and 2xx families were purchased parts specifications. But I find no
example of a 278 filter in my filter boxes. It is possible that 278
applies to some modern mechanical filters.

For any 32S transmitter filter, its important that the bandwidth be 2.1
KHz and the center frequency be 455 kHz, else the carrier crystals will
also have to be replaced to put the carrier 20 dB down each filter skirt
for proper carrier and opposite sideband rejection. If a transmitter is
not performing well its important to check the carrier crystals as well
as the filter.

73, Jerry, K0CQ, Technical Advisor to the CRA
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.