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.)
Thanks,

p.

Try this 5 pole Chebychev with 0.1dB ripple

Fc=17.2MHz BW=1MHz

CAP 1 2 C=27PF
PLC 2 0 L=1uH C=56PF
CAP 2 3 C=4PF
PLC 3 0 L=.1uH C=80PF
CAP 3 4 C=3PF
PLC 4 0 L=1uH C=80PF
CAP 4 5 C=3PF
PLC 5 0 L=1uH C=80PF
CAP 5 6 C=4PF
PLC 6 0 L=1uH C=56PF
CAP 6 7 C=27PF


tia,




Remove "HeadFromButt", before replying by email.

On Fri, 05 Mar 2004 03:08:22 GMT, maxfoo wrote:

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.)
Thanks,

p.

Try this 5 pole Chebychev with 0.1dB ripple

Fc=17.2MHz BW=1MHz

CAP 1 2 C=27PF
PLC 2 0 L=1uH C=56PF
CAP 2 3 C=4PF
PLC 3 0 L=.1uH C=80PF L=1uH sorry!
CAP 3 4 C=3PF
PLC 4 0 L=1uH C=80PF
CAP 4 5 C=3PF
PLC 5 0 L=1uH C=80PF
CAP 5 6 C=4PF
PLC 6 0 L=1uH C=56PF
CAP 6 7 C=27PF



how did that decimal point get there on plc 3 0??
inductors should all be 1 microhenry.




Remove "HeadFromButt", before replying by email.

On Fri, 05 Mar 2004 03:08:22 GMT, maxfoo wrote:

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.)
Thanks,

p.

Try this 5 pole Chebychev with 0.1dB ripple

Fc=17.2MHz BW=1MHz

CAP 1 2 C=27PF
PLC 2 0 L=1uH C=56PF
CAP 2 3 C=4PF
PLC 3 0 L=.1uH C=80PF L=1uH sorry!
CAP 3 4 C=3PF
PLC 4 0 L=1uH C=80PF
CAP 4 5 C=3PF
PLC 5 0 L=1uH C=80PF
CAP 5 6 C=4PF
PLC 6 0 L=1uH C=56PF
CAP 6 7 C=27PF



how did that decimal point get there on plc 3 0??
inductors should all be 1 microhenry.




Remove "HeadFromButt", before replying by email.

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

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

AADE http://www.aade.com/filter.htm




"Paul Burridge" wrote in message
...
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.)
Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

AADE http://www.aade.com/filter.htm




"Paul Burridge" wrote in message
...
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.)
Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

"Paul Burridge" wrote in message
...
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.)
Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

Download the freeware filter design software from

http://www.nuhertz.com/

Their UI is, uh, colorful, but it seems to work. Pay attention to the source
and load impedance. Also, it doesn't like 'engineering' notation (eg:
17.2Meg), so use scientific notation like 17.2e6 instead.

The freeware only designs filters to 3rd order, so if you need better than
that, either dig it out of a book or buy the software. However, it does both
passive and active filters. Its a bargain at twice the price...

Regards,
Bob Monsen

"Paul Burridge" wrote in message
...
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.)
Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

Download the freeware filter design software from

http://www.nuhertz.com/

Their UI is, uh, colorful, but it seems to work. Pay attention to the source
and load impedance. Also, it doesn't like 'engineering' notation (eg:
17.2Meg), so use scientific notation like 17.2e6 instead.

The freeware only designs filters to 3rd order, so if you need better than
that, either dig it out of a book or buy the software. However, it does both
passive and active filters. Its a bargain at twice the price...

Regards,
Bob Monsen

Download RFSim99 and let it do it for you. Download Filter Design
from AADE's site and let it do it for you. Download NuHertz's demo
version of their filter design software and let it do it for you.
There may even be web aplets that will do it for you. And then you
can play with configurations and shape factors and the inevitable
tradeoffs between complexity and shape factor.

Cheers,
Tom

Paul Burridge wrote in message . ..
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.)
Thanks,

p.