[amsat-bb] IC-821H problems - SOLVED

R.T.Liddy 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

and FO-29.

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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