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


Brett Gazdzinski brett.gazdzinski at verizon.net
Sun Jan 27 20:19:07 EST 2008


I would put a kiwa filter in place of the if cans, or
in between them.
Look at the standard filter module, it has no loss through the filter,
works like a mechanical filter, and you can tack the wires onto
the circuit without any drastic drilling or blasting.
I use there filters in the homebrew receivers and they work
better then you would believe.
Plus, they are small.

I dont have a diagram, but the filters work best just
after the mixer and before the 1st IF amp.
In the homebrew receivers, I used a broad band IF trans after the mixer
(from old tube type car radios!) then into the filter.
If you have any radio with a 455KHz IF, these filters are easy to add.


http://www.kiwa.com/index.html


Brett
N2DTS

----- Original Message ----- 
From: <sbjohnston at aol.com>
To: <gzook at yahoo.com>; <amradio at mailman.qth.net>;
<glowbugs at piobaire.mines.uidaho.edu>
Sent: Wednesday, January 23, 2008 12:33 AM
Subject: [AMRadio] Re: GB> 75A-2 project


> 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
> http://www.wd8das.net/
> ------------------------------------------------
> Radio is your best entertainment value.
> ------------------------------------------------
>
>
> -----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
>
>
>
> _________________________________________________________________________
> ___________
> Never miss a thing.  Make Yahoo your home page.
> http://www.yahoo.com/r/hs
>
>
>
>
>
>
> ________________________________________________________________________
> More new features than ever.  Check out the new AOL Mail ! -
> http://webmail.aol.com
> ______________________________________________________________
> Our Main Website: http://www.amfone.net
> AMRadio mailing list
> List Rules (must read!): http://w5ami.net/amradiofaq.html
> List Home: http://mailman.qth.net/mailman/listinfo/amradio
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:AMRadio at mailman.qth.net
> To unsubscribe, send an email to amradio-request at mailman.qth.net with
> the word unsubscribe in the message body.



More information about the AMRadio mailing list

This page last updated 13 Dec 2017.