[UK-CONTEST] Bandpass Filters

[Andy Cook, G4PIQ]

I built a load of these filters for multi-multi at M6T. They are pretty
effective on the lower bands - up to 40m. 20 is OK, but 15 and 10 are really
quite broad and only offer 10/15 dB rejection in the other band. The series
capacitor needs to be able to handle decent current and I resorted to
wrapped mica caps on the high bands for these after a few failures from some
(admitted old) junk box 750V brown mica things. The modern mica caps seemed
to stand up OK on the low bands.

I used the ICE switched 6 box filters for SO2R at the moment which are OK,
but not great design - I;'ve never liked the way the LEDs flash with all the
RF around and I have had to disable some LEDs where they have ended up being
noise sources - I think damaged from the RF.

Andy

> -----Original Message-----
> From: uk-contest-admin at contesting.com
> [mailto:uk-contest-admin at contesting.com]On Behalf Of Jim Martin
> Sent: Friday, January 10, 2003 11:45 PM
> To: uk-contest at contesting.com
> Subject: [UK-CONTEST] Bandpass Filters
>
>
> Just getting down to making a set for the SO2R set-up.  The
> design I have is
> from K4VX dated 1988 using a 3 pole Butterworth BPF.
> Couple of questions, is this still a good design to use or have other
> reproducible designs been published?  ( Ideally they would
> cope with 150w of
> RTTY but I suspect this would put the cost through the roof!)
> Regarding suppliers, are there UK companies who will supply
> Amidon cores and
> other suitable components to the public?
> Thanks
> Jim  MM0BQI
>
>
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