[R-390] R-390A Multiple Signal Peaks

[John Kolb]

That would be me ;)

The R-390A filters can be found on the page
http://jlkolb.cts.com/site/mfcurves.htm

Click on the links for the Collins F455N-20, -40, -80, and -160
for the 4 filters. The 2 kHz and 16 kHz filters that I linked
for these curves do exceed the ripple specification of 2 db max.

Here's another 2 kHz filter that does meet spec for ripple
http://jlkolb.cts.com/site/curves/F455N202.PDF

If testing the receiver with a signal generator, the filter ripple
can be measured by increasing the generator output until the meter 
reads the same level as the high peaks, and see how many db stronger
the generator output had to be.

John

---- Dennis Wade <sacramento.cyclist at gmail.com> wrote:
>
> It sounds to me like your seeing the passband ripple of the filter in
> use.  I seem to recall a discussion of that feature of mechanical
> filters, especially the wider ones, on this list in years past.  There
> is also, somewhere on the web some good plots of filter response taken
> by one of our own here.  The more organized among us will probably
> post the link shortly.  :)