[Collins] Inrad 2.5 KC Mech Filter Assembly

[Dr. Gerald N. Johnson]

Lot of people like the wider bandwidth. I'd think setting the BFO 
crystals to the right part of the slope would be a bother since they 
aren't adjustable and matching for transceive would be out of the 
question. But then the S-3B has a tunable BFO and you can always use 
manual spotting with the PTOs independent. I have a modern torsional 
mechanical filter pair in a Yaesu and they don't ring on static nearly 
as long as the original 75S filter F455FA21. But I use an external 
passive audio low pass filter to narrow the pass band from 2.4 down to 2 
from my years of using the 2.1 in my 75S-3B.

The original filter converts lightning summer times on 75 meters from a 
click in other receiver but it comes of the ringing filter as a craaaaash.

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

On 1/19/2012 10:24 AM, Byron Tatum wrote:
> Hello-
>      I am restoring a 75S-3B receiver and found the Inrad 2.5 KC mech filter
> PC board assembly plugged in, in place of the usual Collins 2.1 KC filter. This
> Inrad assembly has the Collins #526-8694-010 torsional mech filter. I thought I
> would ask list members their opinion of this filter as compared to the standard
> #526-9427-00 2.1KC filter. Is this a desirable filter to keep in your 75S-3B?
>                                                          Sincerely,
>                                                                  Byron WA5THJ
>