You might want to check the approach that Rockwell Collins uses in the
HF-8023 (I believe that is the SS one). It uses a really cool approach to
setting
up the board layout to minimize the inter-band coupling effects. It's easy to
copy, just go the the Patent (US Patent 4,349,799). The patent was awarded in
1981 so it is still in force (if Rockwell is still paying the annual fees)
but I am sure they won't bust you if you make one for your hobby amp. Just
don't go into business selling them.
You can read or print the patent for free on the US Patent office website:
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&;
u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4,349,799.WKU.&OS=PN/4,349,799&
RS=PN/4,349,799
There is also a good description of the filter in Sabin's last book.
Also, I have a really nice harris LPF assy, actually two of them. One is out
of a smaller radio, and the other is in my Harris RF-3230. The 3230 has a
really creative filter, but it is built for more attenuation than you probably
need---it is a 7-pole filter!
Take a look at the Collins...I really like their approach.
John
K0UM
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