[amsat-bb] IC-821H problems - SOLVED
k8bl at ameritech.net
Thu Jul 13 22:06:22 UTC 2017
Thanks for sharing the solution/story!
Many times folks look for help here and don't
come back to tell of the resolution after several
people make the effort to give suggestions. That's
Glad you got things ironed out.
73, Bob K8BL
From: Matthew Stevens <matthew at mrstevens.net>
To: amsat-bb <amsat-bb at amsat.org>
Sent: Wednesday, July 12, 2017 7:33 PM
Subject: Re: [amsat-bb] IC-821H problems - SOLVED
Just for future information, I (sort of accidentally) solved my
problem! While setting up for field day a couple weeks ago, I checked
my antenna (an Alaskan arrow, using only the bottom 2 sections) - and
was surprised to notice it was around a 2.2:1 SWR on 435MHz. I thought
I remembered it being better than that, but I guess not. I set up the
full-length antenna for Field Day, and operated using a borrowed
IC-910 (just in case my radio had the problem again.) In the full
length configuration, the alaskan arrow is a 1.1:1 match on 435MHz.
A few days after field day while I was putting away my equipment,
something dawned on me - I have never had a problem with the 821 while
using the antenna in its full length configuration. I don't use it
that way very often, primarily for very low (sub 2°) passes of AO-7
You can probably see where this is going....My theory was that the
high(ish) SWR was causing some RFI problems internally in the radio.
RF going where it's not supposed to be, on the coax shield etc. I
would think that it shouldn't be a problem for the radio to cope with
a 2:1 mismatch...but the only way to find out was test the theory.
I put 2 wattmeters inline, one each on the 2m and 70cm feedlines.
Transmitting at ~25w on 435mhz, I was seeing around 2.5-3w coming back
towards the radio on my 2m feedline. Figuring that probably wasn't a
good thing, I borrowed a normal arrow II antenna - checked with the
same meter, a 1:1 match on both 435 and 145. Virtually zero reflected
power in the same test. I have been using that antenna for two weeks
now, and haven't had a single problem with the radio.
So, moral of this story is, check the obvious! Even if you think
something is fine, or you think you remember checking it before - make
sure. I had literally checked everything else on the radio, except the
antenna. And for those of you using the Alaskan arrow, it might be
work checking out if it is working as optimally as you think it is. To
be honest, I have yet to find a situation where I could make a QSO
with the alaskan and not with a regular arrow. I will be keeping the
alaskan, probably to use as a base station antenna once I get a mast
and rotor put up at my QTH. But from now on, I'll be sticking with the
regular arrow for my day-to-day ops.
That's the end of my novel.....just thought this might come in useful
for somebody else down the road :-)
- Matthew kk4fem
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