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Re: SUCESS!




Hello Jon.

15 Aug 00 00:24, you wrote to Butterfield:

 JO> When operating satellites, it isn't just a matter of power.  I live in
 JO> the mid-west.  Say I want to talk on a bird when it's on a pass off
 JO> the coast of California.  For me, that could be a very low angle pass.
 JO> It could be difficult to hit.  So I point my beams and crank up my
 JO> power in order to get through trees, obstructions, etc.  But let's say
 JO> you live in California. For you, it might be a nearly overhead pass.
 JO> You are MUCH closer to the bird than I am.  You signal from your HT on
 JO> a couple of Watts will probably get through better than my 50 Watts.
 JO> You'll capture the bird before me.

>From my estimations, this is only true to some extent, as the difference (LOS)
between overhead (800km) and horizon (3200 km) is a factor of 4, or a signal
difference of 12dB.  So your 50W into a _decent_ array could swamp QRP stations
with Arrows underneath the bird.  Now, when you take into account factors such
as local terrain and trees, the 50W could be justified when it's low on the
horizon, as the 12dB disadvantage becomes much greater.

The actual distances are 800km overhead and just over 3300 km for the satellite
on the horizon (taken from my tracking software).  And I'm considering UO-14
here.

 JO> So folks, get off the fact that people that run more power
 JO> automatically get into the FM birds.  IT JUST ISN'T TRUE!  This is
 JO> simplistic terrestrial thinking drilled into us from too much
 JO> operation on the local repeater.

This is true.  There are many factors, and one of the most important factors is
the antennas used.  Here, where there are fewer specialist satellite stations,
the majority of FM satellite users tend to use their terrestrial antenna
systems, which perform poorly on the birds.  As a result, the most successful
stations are the portable ones, most of whom use some form of beam (generally
homebrew) and a HT or two.

 JO> That fact that you have worked stations all over with just 5 Watts or
 JO> less and an HT PROVES that your point is invalid.  You were able to
 JO> capture the bird and make a QSO.  If your point was valid, you would
 JO> never had made those QSOs as all the guys running high power would
 JO> have blocked you out.

I've clobbered a few high powered stations, because my antennas are much better
suited for the purpose.

 JO> The fact is that if people LISTEN more and don't just call and call
 JO> and call, the birds will go smoother.  It really matters not what
 JO> power who is running.  If the bird hears you, it hears you.  Your
 JO> skill in operating is what sets you apart from the rest.  If everyone
 JO> listened (including the high power folks), the QRP people would get
 JO> into the bird just fine.  So listen,
 JO> listen, listen, listen and listen again.

The most important word. :)   The most common problem I see with satellites is
that many people running terrestrial gear have severe problems with the
downlinks, especially on 70cm.  And some of these stations insist in calling,
which creates only QRM.

For anyone new to FM satellites, LISTEN!  Make sure you are receiving the
downlink.  It is actually possible, with experience, to hear the signal from
the bird when it contains only the noise from the uplink Rx (this is a common
scenario for VK), as the retransmitted noise is usually a few dB lower than the
receiver's own (no signal) noise, and has a slightly different tonal quality
about it.

Terrestrial antenna systems are not much chop at all, with a few exceptions,
which are:

3/4 wave vertical - Quite good for high elevation passes - I have been able to
reproduce the good performance that others have observed with these antennas.

Yagi or other beam - Good for passes on the horizon.  Will work the full pass,
if elevation rotors (or hand pointing!) are used.

Also, use a masthead preamp if running more than a few metres of coax.

For the FM birds, I would recommend trying one of the following.

If you have the money/time/QTH, some nice crossed Yagis or other CP antennas
with Az/El rotation (and optionally, computer control) will work a treat. Might
as well go for multimode radios here and work more of the birds up there :)

For the more agile, a portable station, consisting of a HT or two and a
portable beam (either commercially built or home brew) makes an excellent
performing FM satellite station.

The minimalist station - simply a 2m 1/4 wave, with a diplexer and a pair of
VHF/UHF FM rigs can work well on high passes.  Not a bad choice for mobile
stations.

The rover - A pair of HTs and whips optimised for the bands used will work in a
pinch.  Takes a bit more work, but this setup is the most portable of the lot,
and can go places where others can't (I think I'd have fun trying to get my
beam on an airliner :) ).

Just a few ideas which have proved successful (I haven't tried the first, but
one can dream on :) ).

I haven't done any real work with fixed antennas, so can't really comment on
the performance of turnstiles, eggbeaters, etc.

 JO> The good Lord gave you two ears and one mouth.  Use them in that
 JO> proportion!

:-)

Tony

.. Save the turtles. Don't wax your car.
--
|Fidonet:  Tony Langdon 3:633/284.18
|Internet: tlang@freeway.apana.org.au
|
| Standard disclaimer: The views of this user are strictly his own.


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