[amsat-bb] IC-821H problems - SOLVED
matthew at mrstevens.net
Wed Jul 12 23:33:00 UTC 2017
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
On Sat, Jun 17, 2017 at 11:59 PM, Nitin Muttin <vu3tyg at yahoo.co.in> wrote:
> Hi Matthew,
> I feel this could be related to the "Ribbon Cable contact issue ". There is
> one ribbon connector behind the S meter which goes to one of the boards.
> Disconnect the cable by pulling on the connector socket clean the pins on
> the cable with a rubber eraser (soft) and fix back the connector.
> Nitin [VU3TYG]
> From: Matthew Stevens <matthew at mrstevens.net>
> To: Nitin Muttin <vu3tyg at yahoo.co.in>
> Cc: "amsat-bb at amsat.org" <amsat-bb at amsat.org>
> Sent: Saturday, 17 June 2017 12:18 AM
> Subject: Re: [amsat-bb] IC-821H problems
> Yes, I do. Interestingly, I have not had any problems with FM in
> either mode J or B. The other day I worked AO-85 successfully, and
> immediately switched to EO-79, 2m SSB downlink. I heard no telemetry
> or anything else. Then I pointed the antenna over towards some nearby
> powerlines, which normally create a lot of annoying static on 2m -
> nothing heard. I removed the coax from the 2m jack, and observed a
> drop in the noise level (very slight), reconnected the coax and
> checked over towards the power lines again, with the same result. I
> wasn't hearing anything on 2m SSB, after I had, minutes before, had no
> issues hearing on 2m FM.
> I'm glad I have other radios to use in the meantime, while I try to
> figure this out :-)
> - Matthew kk4fem
> On Sun, Jun 11, 2017 at 2:05 AM, Nitin Muttin <vu3tyg at yahoo.co.in> wrote:
>> Hi Matthew,
>> On 2m when on FM mode do you hear the white noise when you open the
>> Nitin [VU3TYG]
>> From: Matthew Stevens <matthew at mrstevens.net>
>> To: amsat-bb at amsat.org
>> Sent: Saturday, 10 June 2017 7:06 PM
>> Subject: [amsat-bb] IC-821H problems
>> I'm having a strange issue with my 821. Periodically I lose all
>> sensitivity, which I've particularly noticed on 2m SSB. I can attach and
>> detach an antenna with no change in the noise level, and can't hear anything
>> in the receiver (like the XW-2* beacons, or the AO-73 telemetry). Resetting
>> the radio seems to fix it.
>> It doesn't appear to be affecting 70cm, although I haven't had much chance
>> to test that (there's not always a mode j sat up at the same time as a mode
>> b one, and when it happens I'm normally just trying to reset the radio as
>> fast as I can do I can operate the pass). Has anyone experienced anything
>> like this before?
>> - Matthew kk4fem
>> Sent from my iPhone
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