Hi Pete,

Craig Siegenthaler and I have been friends since 1988, so we go back a ways,
and I'm very partial towards his design abilities and products. Apart from
my bias, there's a great value in Kiwa's Premium Filter Modules-- $75.00 for
a filter with typically greater than 100 dB USB ultimate rejection and shape
factor typically 1 to 1.65 is money well spent. The final, resulting
performance depends on the entire receiver system and PCB layout/shielding,
as you mentioned.

The very best filters I've encountered (before I went IF-DSP with the
756Pro) were matched-pair INRAD crystal filters, and the crystal filters in
my RA6790GM.

BTW, before Craig offered filter modules using cascaded ceramics, he tried
the same idea in the Kiwa Multiband AM Pickup (MAP) accessory in the
1989-1991 timeframe. This device provides outboard synchronous detection
plus two IF bandwidths, notch, tone tilt, IF output, low distortion speaker,
and other features. The closest competitor is (was) the Sherwood SE3.

The filter characteristics in my particular MAP are excellent-- the actual
measurements from the Certificate of Performance show an ultimate rejection
at 3.5 kHz of -108 dB and shape factor of 1 to 1.53 in the narrow bandwidth
(3.0 kHz @ -6db nominal) for my particular serial number. The passbands are
also kept flat within +/- 2.0 dB for both the wide and narrow IF bandwidths,
something you don't always find in discrete crystal & mechanical filters.

73,

Guy


"Pete KE9OA" wrote in message
...
Craig's filters are very good, with good ultimate rejection, but
Mechanical Filters have an ultimate rejection of 120dB. True, this figure
is better than the dynamic range of most receivers, and also true, you
have to have very good shielding/ground in your PC board layout scheme in
order to obtain this 120dB figure.
100dB ultimate rejection is a good figure to shoot for. I have spoken to
Craig a few times.....he is a very good designer.

Pete

"Guy Atkins" wrote in message
...
Craig at Kiwa Electronics seems to have figured out how to make quality
filter modules from series-cascaded Murata ceramics. He uses low noise
buffer amps as part of the package in Kiwa's Standard and Premium Filter
Modules (PFMs). The latter are particularly good, with ultimate rejection
figures exceeding Collins mechanical filters and better shape factors
than quality crystal filters... and at a very good price for the
performance.

I've used a number of PFMs over the years in various receivers, and
they've performed excellently for DXing and program listening.

http://www.kiwa.com/kiwa455.html

Guy Atkins
Puyallup, WA USA


"Arthur Pozner" wrote in message
...
Murata filters are not known for good shape factor(6db//60db) . When
stacked in series losses mount rapidly. And they seem to have a lot
more noise when compared to crystal or mechanical IF filters. Have you
tried to build a crystal ladder filter? Very effective and MUCH cheaper
than any other IF badpass filter ,and Inrad is not the costliest-
KVG,Collins etc.may set one back many hundreds of dollars...