I had a set of ICE bandpass filters that never saw more than 100w - used
them on my Icom 751A to drive an amp. After I had used them for a few years
I checked for insertion loss and passband. Some had changed. When I opened
up the ones that had changed I could see some caps that were blackened and
they had a burnt smell. That's when I bought a set of W3NQN filters.
[mailto:firstname.lastname@example.org]On Behalf Of David Hachadorian
Sent: Friday, December 10, 2004 4:20 PM
To: Towertalk Reflector
Subject: Re: [TowerTalk] ICE 419A Combination Bandpass Filter 10M Section
----- Original Message -----
From: "Keith Dutson" <email@example.com>
To: "TowerTalk" <firstname.lastname@example.org>
Sent: Friday, December 10, 2004 12:39 PM
Subject: [TowerTalk] ICE 419A Combination Bandpass
Filter 10M Section Blown
> Subject says it all. VSWR went to 5 at some point
> during operation of
> VP8WWW. The filter box was set to 10 meters and
> connected to a trapped
> vertical and Kenwood 480HX. Transceiver was set to
> 200 watts CW on 10
> meters. We were using two boxes and switched them.
> About an hour later the
> second box did the same thing.
> I read the manual. It states the unit is rated at
> 200 watts. I am guessing
> that is for SSB rather than CW. Anyone else
> experience this problem?
> Each filter section apparently consists of a simple
> coil and two caps in T
> configuration. This is only an observation as I do
> not have a schematic. I
> would like to beef up the capacity and assume this
> might be done with higher
> voltage caps.
> Keith NM5G
A friend of mine has the ICE filters, and I have helped
him change bad 10 meter capacitors twice now. At least
one other person has publicly complained of the same
thing. The factory guys say they have never heard of
such a problem. They did supply the replacement caps
for free, but it took a few weeks to get them, and by
then we had already purchased the replacement caps from
Mouser. The cap that failed both times was in the leg
that runs to ground on the rig side, not the antenna
side. This leg is a parallel combinaton of two caps.
The cap did not blow completely, rather it just made a
significant change in value. If you separate them you
can use an impedance measuring device, such as an
antenna analyzer, to figure out which one has changed.
The capacitor values are all different for the various
bands, but a typical Mouser part number would be
5982-19-500V270 for the 270 pF. The Mouser catalog does
have some 1000V micas, but the selection of values is
quite limited. You could switch to a parallel/series
combination of four 500V caps, at least in this leg.
Another thing I don't like about the ICE Filters is
that the signal path goes through 12 normally-closed
relay contacts. In my friend's units, he experiences
occasional signal dropout on receive. As soon as he
sends one 50 watt "dit" through the filter, the film on
the relay contacts is penetrated, and the receive
signals reappear. The factory guys say they have never
heard of that one, either.
Just pull the cover off the filter, and you will see
how it is built. At least it is easy to work on. We've
had the covers off my friend's unit so much that now we
just have to whistle, and the screws unscrew
themselves. After you change the caps, just squeeze the
10 meter coil/bend cap leads for min swr. We keep a
rubber glove handy for this purpose, to avoid rf burns,
and to avoid affecting the swr. Make final adjustment
with the cover on as far as you can get it, and still
be able to reach in. We can change these caps in about
ten minutes now. It looks like a Wood brothers' pit
Dave Hachadorian, K6LL
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list