----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
> On Mon, 22 Nov 2004 15:07:17 -0500, Joseph Dube wrote:
>
> >I was wondering if anyone on the reflector had any information a source
> >of highpass filters that could be placed in line with a transciever?
>
> ICE (in Indianapolis) makes decent high pass filters with a cutoff just
below 1.8
> MHz. I have two of them, one of which is in line with my rig all the time.
It works
> quite well. I've also measured it using lab quality test gear, and it
meets its specs
> quite nicely. Cost is about $40. Google to find them. The broadband
trash on 160
> dropped a few dB when I inserted it.
One caveat is that this filter has limited rejection (only 10
to 15dB) at the high end of the BC band:
http://www.arraysolutions.com/Products/ice/filtersrf.html#bcb
If you have a severe fundamental overload problem from a
station high up in the band, this filter may not provide enough
rejection. I had that problem when trying to keep the front-end
of my ANC-4 noise cancellor from overloading when I lived
in Melbourne, Florida. The pre-amp in the ANC-4 folds over
at the drop of a hat, so I needed to build my own filter with
a notch to protect it from a nearby station (1560 I think it was).
Otherwise its a good filter, although mine died after I left
it over at W6UE for a while. I think, however, someone put
it at the output of the amplifier instead of between the amp
and the exciter where it belongs. The core material in one
of the shunt inductors looked discolored when I took it apart.
73 de Mike, W4EF.................................................
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