[Yaesu] Collins Filter F455FA21

[Hardy Landskov]

I have used a 5.8 KHz Collins Mechanical Filter (P/N 526 8636 010) in my 
FT-990 in place of the AM ceramic filter with excellent results. I changed 
the bias resistors from 4.7K to 2K and added 30 pF caps to ground to get the 
impedance levels right. The 2K resistors more than doubled the bias current 
which PIN diodes like anyway. Note: I got rid of the computer diodes in the 
radio that were used for switching.
I don't see why you could not do the same. The older Collins filters are big 
and hard to shoe horn in. The newer ones are very small and give practically 
the same performance with a little sacrifice in ultimate rejection as I 
remember.
73 Hardy N7RT

----- Original Message ----- 
From: "VO1HP" <fdavis at nfld.net>
To: <yaesu at contesting.com>
Sent: Wednesday, November 05, 2008 6:13 PM
Subject: [Yaesu] Collins Filter F455FA21


> Has anyone tried to use a Collins F455FA21 filter (same filter used in 
> 75S3B) in the orgional MP sub receiver to replace the ceramic filter?
>
> Frank VO1HP
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