[Collins] Mech. Filter loss in 75A-4 SOLVED!!

[Barockteer@aol.com]

Thanks to Ian, K6SDE, who first suggested looking at the input/output caps on the filters, I have solved my problem.

First, I removed all the filters and checked the input/output caps using a capacitance meter (Autek RF-1 actually). I found the output cap for the 'C' position was open.

When I took the bottom cover off, I could see that someone had neatly cut one lead of C133 with a pair of dykes!

After checking to see that the cap was not shorted, I soldered it back into the circuit.

The filters now work much more like I would expect, with only moderate changes in insertion loss with bandwidth.

Thanks to all who responded with suggestions!

73,
Tony, K1KP