[amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE
wb3jfs at cox.net
Fri Oct 2 03:02:08 PDT 2009
Sorry for the long reply. Between other e-mails, work and the RTTY contest
over the weekend, I've been trying to find time. Your e-mail has raised
some questions I had to think about or gather additional information.
As for the Arrow loosing its speckles and plastic tips. My belief is though
the antenna is basically designed to be used as a portable setup, a
permanent setup can be configured using the same antenna. However, being
outside in certain climates, aluminum can become rather oxidized and very
quickly too. Here in the desert, I've yet to see this occur on a severe
case, like I used to see back in PA. I've seen aluminum poles in place for
4 years and when the sun hits it, there is a huge shine. The tips of the
antenna are probably not UV hardened. Again, it was probably designed with
portability in mind and not a base station setup where it would remain
The observations I've been making with the Comet diplexer and the Arrow
diplexer have been made with multiple passes at different elevations,
ranges, etc. Strictly comparing previous passes, at the same elevations, to
current ones with taking into consideration how the downlink compares.
You made the statement that you "view all anecdotal comparisons of before
and after results with some caution." Which should be true in all cases not
matter what the subject is. However, when you also questioned about the
improvement of fades during a pass due to a diplexer change then asked "It
is so, please tell me the science behind this." I must say there isn't any
science behind it because anecdotal evidence is obtained through reports or
observations of unscientific observers. Again, this is basic gathering of
observations based on changing one device, the diplexer.
As for AO-27 turning off near the 49th parallel, I don't believe there is
any anti-Canadian sentiment for this. :) Think about it this way, what if
you lived near the 49th parallel in the southern hemisphere? Talk about
anti-sentiment. :) If I recall correctly, the timer is set to turn on
around the pass of the 28th parallel and off 7 minutes later, which takes it
to near the 49th parallel. I would like to see AO-27 opened for 8 to 9
minutes if it could be spared. I've had some really nice passes get cut to
digital with so much more room to LOS. So I guess maybe we should ask if it
is possible to extend the timer by 1 or 1.5 minutes, if the bird can spare
----- Original Message -----
From: "Alan VE4YZ" <ve4yz at mts.net>
To: "'AMSAT-BB'" <amsat-bb at amsat.org>
Sent: Friday, September 25, 2009 8:44 PM
Subject: [amsat-bb] Re: Arrow antenna reconfiguration results - UPDATE
>I rarely use my Arrow and 2 dual band HTs, but, dragged them out this week
> because I'm scheduled to do a high school demo in 2 weeks and thought I
> better start practicing my technique again, update the KEPS in my Palm
> PocketSat+ and get the battery packs charged.
> So this discussion in the last couple of days is very relevant to me and
> here's my 2 cents...
> The only compliant I have about the Arrow is that it looses it's speckles
> and the plastic tips fad to white when used outdoor for long periods :-)
> Several years ago I ran it for a full year on the roof with a hygain TV
> rotator and fixed EL of about 30 degrees. The arrows are now plain
> First I view all anecdotal comparisons of before and after results with
> caution. A diplexer change from the OEM to another cannot account for the
> improvement in one pass with fades to the next pass with no fades IHMO.
> is so, please tell me the science behind this. If a defective diplexer
> acting as an attenuator then I sure can see there would be an improvement
> signal. In my location, 2 low passes with the same max elevation on the
> same satellite can be quite different depending on which part of the
> is below the pass - open prairie vs the noise floor of city. Sometimes
> are fades and sometimes there aren't any. Satellites tumble. Sometimes
> your advantage and some times they work against you.
> Now, as to the Arrow OEM diplexer; with the 2 HT's I don't use it except
> a mode J filter, see
> http://www.amsat.org/amsat-new/articles/Mode-J/ to reduce desense, and, a
> mini UHF preamp
> http://www.hsmicrowave.com/html/amateur_lna.htm , and, anecdotally I can
> tell you that I can see the increase in bars on S-PO Meter and these old
> ears can hear the difference when the preamp is switched on and off.
> For those of you who want to use an external diplexer such as a Comet, you
> can still use the OEM diplexer at the same time as a filter.
> BTW yesterday I just practiced listening and heard a monstrous booming
> signal from ISS, got to hear 4 or 5 answers to questions during the Ottawa
> ARISS with the Arrow and a max 10 degrees pass, no preamp needed, LOS
> under 5 degrees. Also AO-27 max 20 degrees over Eastern NOAM until it
> digital - ever notice it goes digital just as it hits the 49th parallel?
> that an anti-Canadian thing?
> 73, Alan VE4YZ
> AMSAT LM 2352
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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