[amsat-bb] Just received UAH ARISS contact - much harder to rx than normal. Arrow antenna problem?

John Brier johnbrier at gmail.com
Fri Feb 19 18:21:51 UTC 2016


Yeah that kinda sounds like my experience except I had difficulty through
most of the first half and the second half.

There was a point in the beginning where I realized I was aiming way off.
It was actually at max elevation for me and I was still aiming towards
where the beginning of the pass was. As soon as I aimed higher and in the
right direction it came in very strong and I didn't have to hold the
antenna in a sweet spot.

But a minute or two later, towards the end of the pass I had to have the
antenna rotated for the right polarization and direction. It was
interesting in that I could really tell exactly where the ISS was because I
had be precisely on target. Faraday rotation was very dramatic too, just
slightly off axis on the polarization and I lost the signal entirely. Of
course I have video of this all so it will be very interesting to review.

One extra bit of trouble-shooting info: I was able to receive and get into
a repeater 120 miles away. It's one I've gotten into several times from up
here on my landfill park, and the signal and my report was about like
normal. So that suggests there might not have been an issue with my antenna.

The only other thing I can think of was that I did not adjust for doppler
in the beginning. When I finally tried to a minute or two (or three?) into
the pass it didn't make a difference. Though I guess at that point you
should be on the center.frequency anyway.

But I almost never adjust for doppler and it's fine. Even on the last pass
I did before this over K6DUE in Maryland, which is even closer to me than
Alabama and which made for a higher pass and thus had a more dramatic
change in speed relative to me, it made very little difference.

73, KG4AKV
On Feb 19, 2016 12:57 PM, <skristof at etczone.com> wrote:

>
>
> I also used an Arrow antenna with both 2 m and 70 cm elements installed.
> I had some trouble at first, but I think it's because I was still
> fiddling with my radio. I thought I had it set up ahead of time, but I
> didn't. Anyway, the first few minutes were rough, but the rest of the
> transmission was received just fine.
>
> Steve AI9IN
>
> On 2016-02-19 12:51, John Brier wrote:
>
> > It took much longer into the pass to pick up a solid signal and when I
> got
> > it, except for the top of the pass I had to aim the antenna perfectly to
> > get the signal.
> >
> > The only thing differently about my setup today was I had the 70 cm
> > elements installed on the boom too because I was using it to work SO-50
> > recently and didn't have time to take them off.
> >
> > Could this make the antenna less sensitive on 2 meters? Because that's
> what
> > it felt like. Very dissapointing for me since I normally have no trouble
> > getting the ISS from horizon to horizon.
> >
> > With that said it sounded like they got through all of their questions
> and
> > Tim Kopra got to say goodbye.
> >
> > In his goodbye he repeated part of his answer to a question, saying one
> of
> > the most important things to do to get space was to play nice with
> others.
> > He said it wasn't important just in getting to space but also for life in
> > general. A great message.
> >
> > Congrats to all involved in this succesful contact, but someone please
> tell
> > me why it was so hard for me to receive!
> >
> > 73, John, KG4AKV in FM05
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