It's been years since I designed an active filter; but IIRC one could recenter
the filter by multiplying the R's and the C's by new_center_frequency /
old_center_frequency. Basically, the capacitors should get slightly smaller;
and the resistors should get slightly smaller too.
If you can't find the article, try looking at active filter design. Or even
passive filter design. There are massive filter tables, listing the parameters
for the elements; but they are designed for 1 radian per second frequency. It
is normalized to one frequency so as to make it easy to move to any desired
frequency. So, if you read some of the background on how to design using those
tables, you should be able to hone in on how to rework it.
Shawn Upton, KB1CKT
NAQCC 4723
________________________________
From: Stan Barr <g0clv@dsl.pipex.com>
To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Sent: Thursday, April 5, 2012 2:21 PM
Subject: [TenTec] Century/22 filter frequency mod.
Hi,
I have a Century/22 and I recall seeing mention of a mod to raise
the audio filter frequency - a little low for my taste.
Can anyone point me to it? I've got to dig inside the rig to
replace the dial elastic (again!) and might as well do any other
mods the same time.
Thanks in advance...
--
Cheers and 73,
Stan Barr G0CLV GQRP-3369 FISTS-667 g0clv@dsl.pipex.com
"Never leave well enough alone." - Raymond Loewy
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