[Lowfer] Thank you !

[John Andrews]

Les, and others:

> "The 500hz filter is really unnecessary for Argo. The software only looks
at
> a very section of bandwidth (much narrower than 500hz) so it does you no
> good."

As Bill points out, that is only part of the story. If there is a nearby
interfering signal that could be attenuated with an IF filter, here are two
possible scenarios:

1. AGC on. If the receiver's AGC is on (my default condition for unattended
recording), then the AGC may be governed by the interfering signal, causing
the receiver gain to be reduced. A narrower IF filter that attenuates the
interfering signal but passes the desired frequency would be a help in this
case.

2. AGC off. With the receiver's AGC off, interfering signals may determine
how high you can manually set the RF gain control before overload occurs.
Turning down the RF gain control may put your desired signal too far into
the receiver's internal noise to be copied.

This season, I have been running with the 500 Hz first IF filter that I used
last year, plus a 250 Hz second IF filter. While I can't demonstrate that it
has helped, it sure isn't hurting anything!

All of that being said, my preference for regular CW reception is completely
the opposite. When copying by ear, I keep the receiver as wide-open as I can
stand it, because it "sounds better" to me. If I try to use Spectran to copy
a weak, regular-speed CW signal, I find that the screen looks cleaner with
the wider BW.

John Andrews, W1TAG