Scott wrote:
I want to build a low pass filter for 1296 and have scaled a design out
of the handbook. I would like to use chip inductors and chip capacitors
for the filter. I was looking at thin film chip inductors (Digi-Key)
and they list the self resonant frequency. For an inductor passing
1296, what should the minimum self resonant frequency be? Is 10 GHz
enough? The filter is a 5 element Chebyshev Low Pass Filter, inductive
input (3 coils in series with a cap at each inner junction to ground),
Fco=1290 MHz, F-20dB=2600 MHz. Any other component specs I need to be
aware of?

Scott
N0EDV

Adding to what others have already posted, you can simulate the filter,
with parasitic resistances and reactances and the inevitable
transmission line effects, in the freeware RFSim99. You have to be
careful to think about the physical layout, and see everything longer
than a couple millimeters as a transmission line. The data sheets on
the discrete parts should give you a decent idea about the parasitic
R/L/C of each package. RFSim99 includes the ability to model
self-resonance and Q in inductors and capacitors without adding more
parts to the schematic; just check the "use physical model" box for
those parts you want to specify for Q and SRF.

And I'd echo what Tim wrote, too: you might want to consider a
distributed filter, especially if you can make a PC board with
reasonable accuracy. Also, if the goal is to kill harmonics of a
single narrow band, you may do better with notches at the harmonic
frequencies.

Cheers,
Tom