On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote:

Hi all,

I need a simple design for a BPF with a centre frequency of 17.2Mhz.,
corner frequencies one Meg or therabouts either side of that and a
reasonably good shape factor (nothing critical here). I don't mind
having to do a bit of tweaking of values myself if anyone has
something close to that they can post. Passive L/C combinations only,
please. (assume the usual 50R nominal Zs.)

Lots of books out there with normalized tables. Go to a technical
university library and spend a few hours pouring thru some filter
books. You can use Linear Technology's FilterCad to see what sort of
filter type and order you need. Then hit the tables and make an LC
filter. The best book I have found is "Simplified Modern Filter
Design" by Philip Geffe, circa 1963. You can sometimes find this book
in a university technical library. It has an excellent treatment of
basic filter design and how to go from a low-pass prototype to other
filter types.

For your particular filter, you might consider a loose-coupled design,
also called coupled resonators. Good for Q 10. Your design will just
fit into this category if you don't mind some imperfection. This type
of design produces nice component values. "Electronic Filter Design
Handbook", by Arthur Williams and Fred Taylor (ISBN 0-07-070434-1),
page 5-19 has info.

Mark