The rate at which the attenuation increases away from the centre
frequency is affected by the "order" of the filter (first order, second
order, etc). It would be difficult to filter out nav frequencies from the
com band. Even if the nav radios are the cause, it's unlikely to be a
signal actually in the nav band causing the problem...the thinking is that
it would produce interference in the com band.

The filter from the link would only be used really to see if the cause
of the interference was due to a TV band (50-80MHz?) signalling
causing problems in the receiver, or whether it was something
external causing problems within the com band.

Question (Jim?)...I would expect the image channel rejection to be
pretty good in aircraft radios, is this the case? How about with
handhelds? (and what IF is used?)

Paul

"Snowbird" wrote in message
om...
Yes, that looks like the correct kind of product, but my concern
is it includes the nav radio frequencies. If Aaron is correct that
the problem might be via the nav radios, we need a narrower freq.
range.