----- Original Message -----
From: "Mihail Mateescu" <yo3ctk@alltrom.ro>
To: <CQ-Contest@contesting.com>
Sent: Wednesday, June 09, 2004 9:03 AM
Subject: [CQ-Contest] Bandpass filters for M/S or M/M environment
> Hello,
>
> We are in the process of upgrading the YR7M site from SO capable to
M/S.
> That means, among other, a second workplace equipped with
transceiver and
> linear amplifier. We expect to need bandpass filters at each
workplace.
>
> We have identified three manufacturers for such filters (homebrew is
> excluded since we have barely enough free time to set-up antennas):
>
> ICE via WX0B: model 419A, $228
> W3NQN via WX0B: set of 6 filters, $525 plus FM-6 switch, $165
> Dunestar model 600, $339
> All models are 200W capable.
I use two Dunestar 600's, which I purchased used, and they have worked
well for me for about five years. My antennas are only 6 - 10 feet
apart and I run 1500W. You need to build your own little manual or
automatic control box for these units. The Dunestar units can be wired
for either +12vdc or ground switching.
My friend W7WW has a pair of ICE filters, and they also work well for
him, with his closely spaced antennas and 1500 watts. He has had a few
problems with his though. On initial delivery, one of his boxes had a
problem with the received signal intermittently dropping out. That
unit was replaced by the manufacturer. He has also blown a few
capacitors in the ICE units, even with 100 watts of drive. The caps
actually change value, rather than blow, but the swr goes sky high.
The manufacturer has provided replacements, but we get them a lot
faster from a commercial source (Mouser). It is fairly easy to change
the caps. He now has two low-drive amplifiers, which has solved that
problem for him, at least in the high-power contests. The ICE units
come with a manual DC switch that picks up the internal relays. The
ICE units use +12vdc switching. There is no provision for ground-type
switching.
Dave Hachadorian, K6LL
Yuma, AZ
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