Re: {Collins} 75A-4 -- 6kc or 8kc Filter


As an AM operator in the East, if you are going to install one filter for AM
use, I'd recommend the 6 kHz filter for the A4 because of SSB QRM issues in
and near the typical AM window 3870 - 3890 kHz. If you want to install a
third filter as I have for times when conditions are good, signals strong,
and the station being received is a "broadcast quality freak" (count me in),
then a third filter of 12 - 16 kHz is very nice to have. I have a 16 kHz
non-Collins filter in the third slot and can use it for maybe 80% of my AM
QSOs. This arrangement, however, precludes having a narrow filter for CW.
And the audio in the A4 has been opened up with some component changes to
improve both the low and high end, although the single ended 6AQ5 produces,
as it was designed to do, audio that is far from hi-fi quality.


-----Original Message-----
From: john starr001 [mailto:jstarr001@xxxxxxxxxxx] 
Sent: Saturday, May 02, 2015 7:07 PM
To: collins@xxxxxxxxxxxxx
Subject: {Collins} 75A-4 -- 6kc or 8kc Filter

i just got my first 75A-4 but it only came with a 3.1 filter.  For best AM,
should I be looking for a 6 kc or 8 kc filter?

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