[Collins] Filter Question

[Dr.Gerald Johnson]

I've fixed the lights in the office and dug for my collection of Collins filter 
brochures.

I found F455Q2, F455Q3, F455Q7, and a couple other with the Q part 
number. These seem to be variable not necessarily following logical rules. 
The Q2 and Q7 have bandwidths of 2 and 6.5 KHz respectively but the Q3 
has 40 KHz bandwidth. Most are in a Y package which doesn't plug directly 
into the 75S-3B. I have used Y case filters in my 75S-3B by soldering stiff wires 
on the terminals and spacing them for the transistor sockets. For stiffness I 
used transistor leads. Not all the Q filters were in the Y case.

In my later S-line catalogs, I found that the crystal filters were F455KQ200.

The F455Q-2 was 2 KHZ and part number 526-9309-00 Maybe the F455Q1 
with the adjacent part number is logically 1 KHZ bandwidth. That's purely a 
guess since the filter brochures I have don't show that F455Q1. I don't 
understand the 9W2 nomenclature. Its not proper for a date code, nor 
properly part of the nameplate.

As I mentioned before, it won't be difficult to check the filter passband in 
the working receiver using the crystal calibrator and dial calibration.

73, Jerry, K0CQ

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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.