Thanks for the quick response i have however a few more questions.

This is for notching disturbing tv channels on my tv areal and there are
several that I want to notch.
Lets asume that I only want one Notch pr TV channel is it then possible to
connect several notches on the same spot without the 1/4 wave??? If yes is
there a limit.
I have looked at some commercial filters and they use 2 notch at the same
spot and then two more 1/4 wave apart but the are tuned to the same
frequency as the first pair.

"Dale Parfitt" wrote in message
news:%pXlf.8360$Jg5.8212@trnddc07...

"SH" wrote in message
...
Hi

I am going to make a notch filter with two notches on the same frequency
in the UHF TV band but I cant remember whether they should be spaced 1/4
or 1/2 wave or if it doesnt matter.

Thanks

SH
You can couple the notches directly with an L or C and achieve an
asymmetrical response - this can be handy if yiu have a weak CH close by
on one side and need the faster recovery.
If a symmetrical response is OK, separate the 2 notches by a 1/4
electrical wavelength.
Typical 3dB BW on our small UHF symmetrical notches is +/- 1.2%

73,

Dale W4OP