Alan G3NYK,
OK on the notch filter design, but for a high impedance load.
I have often wanted to try a notch filter in a low impedance feeder, for
such purposes as reducing a TV line oscillator harmonic or other carrier
type of unwanted signal that is a few kHz from the wanted signal, as the
unwanted carrier can paralyse a noise blanker from working effectively (the
bandwidth of the noise blanker is necessarily relatively wide).
On searching for information on notch filters I found a very good series of
articles in Wireless World. Part 2 of the series in September 1979 deals
with low impedance notch filters. The circuit used in "example 4" is a
variant of what you used, with L and C in the leg to ground.
If you can locate old copies of WW you could try modelling a low impedance
notch filter.
73, Bob ZL2CA
|
