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,

Since your too lazy to do this, here, have a few designs. You can run
these on LTSpice. What is reasonably good shape factor?
Mark

Butterworth, pi-input, 1st-order low-pass prototype
Vin 1 0 AC 2.0000V
Rin 1 2 50.000
L1 2 0 26.899n
C1 2 0 3.1831n
Rout 2 0 50.000
..AC DEC 396 253.58kHz 1.1667GHz
..PROBE
..END

Butterworth, pi-input, 2nd-order low-pass prototype
Vin 1 0 AC 2.0000V
Rin 1 2 50.000
L1 2 0 38.041n
C1 2 0 2.2508n
L2 2 3 5.6270u
C2 3 4 15.216p
Rout 4 0 50.000
..AC DEC 792 5.7378MegHz 51.560MegHz
..PROBE
..END

Butterworth, loose coupled, 2nd-order low-pass prototype
Vin 1 0 AC 2.0000V
Rin 1 2 50.000
C1 2 0 2.0654nF
L1 2 0 38.046nH
C2 2 3 185.01pF
C3 3 0 2.0654nF
L2 3 0 38.046nH
Rout 3 0 50.000
..AC DEC 792 5.7378MegHz 51.560MegHz
..PROBE
..END

Butterworth, pi-input, 3rd-order low-pass prototype
Vin 1 0 AC 2.0000V
Rin 1 2 50.000
L1 2 0 53.798n
C1 2 0 1.5915n
L2 2 3 7.9577u
C2 3 4 10.760p
L3 4 0 53.798n
C3 4 0 1.5915n
Rout 4 0 50.000
..AC DEC 1188 10.224MegHz 28.937MegHz
..PROBE
..END

Butterworth, loose coupled, 3rd-order low-pass prototype
Vin 1 0 AC 2.0000V
Rin 1 2 50.000
C1 2 0 1.4607nF
L1 2 0 53.798nH
C2 2 3 130.84pF
C3 3 0 1.3299nF
L2 3 0 53.798nH
C4 3 4 130.84pF
C5 4 0 1.4607nF
L3 4 0 53.798nH
Rout 4 0 50.000
..AC DEC 1188 10.224MegHz 28.937MegHz
..PROBE
..END

Butterworth, loose coupled, 8th-order low-pass prototype
Vin 1 0 AC 2.0000V
Rin 1 2 50.000
C1 2 0 511.07pF
L1 2 0 137.94nH
C2 2 3 109.63pF
C3 3 0 457.95pF
L2 3 0 137.94nH
C4 3 4 53.121pF
C5 4 0 527.60pF
L3 4 0 137.94nH
C6 4 5 39.985pF
C7 5 0 543.91pF
L4 5 0 137.94nH
C8 5 6 36.809pF
C9 6 0 543.91pF
L5 6 0 137.94nH
C10 6 7 39.985pF
C11 7 0 527.60pF
L6 7 0 137.94nH
C12 7 8 53.121pF
C13 8 0 457.95pF
L7 8 0 137.94nH
C14 8 9 109.63pF
C15 9 0 511.07pF
L8 9 0 137.94nH
Rout 9 0 50.000
..AC DEC 3170 15.208MegHz 19.453MegHz
..PROBE
..END