[AMRadio] Re: GB> 75A-2 project

sbjohnston at aol.com sbjohnston at aol.com
Wed Jan 23 00:33:25 EST 2008

Good idea on the swamping resistors...  I did confirm that mine did not 
have the values for narrow bandwidth.  Another list member pointed out 
early and late-model 75A-2s had different bandwidth performance (early 
favoring AM), so perhaps different values were used.

Steve WD8DAS

sbjohnston at aol.com
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-----Original Message-----
From: Glen Zook <gzook at yahoo.com>
To: sbjohnston at aol.com; amradio at mailman.qth.net; 
glowbugs at piobaire.mines.uidaho.edu
Sent: Tue, 22 Jan 2008 7:27 pm
Subject: Re: GB> 75A-2 project

To widen out the bandwidth you can put additional
fairly low value resistors across the i.f. cans.  If
you look in the manual you will see a note to remove
the swamping resistors to narrow the bandwidth.
Therefore, adding resistors in parallel with the
existing resistors should broaden the bandwidth.

Glen, K9STH

--- sbjohnston at aol.com wrote:

The widest bandwidth is 4 kHz (crystal filter out,
just the tuned circuits in the IF stages) and I would
like to add the capability for a wider choice for
Hi-Fi AM reception.  Anyone know of any articles on
such a modification?  Maybe in the context of
"updating" the 75A-2 or 3 to mechanical filters?  Or
have any of your own ideas?

Glen, K9STH

Website:  http://k9sth.com

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