Hello all,
Alan wrote:

Hugh has made up the filter and from workbench tests it seems promising.

Yes it does what it says on the tin ... I got a notch depth of 47dB.
I used a Panasonic ELC08D101E coil available from RS Components part no.
233-5213.
I unwound it and found it had 50 turns. Rewinding with 36 turns and tapping
at 18 gives the correct 50uH.
I think a multiturn pot (or a fixed value resistor in series with a pot)
might be best as it is a very sharp adjustment with a single turn type. I
used polycarbonate film type capacitors (hen's teeth now Bayer don't make
the film any more)
Alan and I are presently discussing impedance matching, as it is 100 ohms
in, 10k out.
73
Hugh M0WYE
http://www.m0wye.thersgb.net/lf.htm

Details on http://www.alan.melia.btinternet.co.uk/BR-t-Notch.htm