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RE: Horizon LEO Link Summary



> easily hear the FO beacons horizon to horizon. [Hearing beacons is one
> thing, working the sats is another, as I'm sure Tony knows 
> all too well.]

Let's say receiving SSB would have been no problem... if there were SSB
stations and I had a SSB receiver on hand.  I did some tests with uplinking
CW and listening on an FM receiver.  The result was very good quieting with
2W uplink into a 2 element Yagi being clearly heard on the TPMII, and 1/4W
on the uplink produced a noisy received signal (would have been readability
5 for CW and 4-5 for SSB).

Also had no problems hearing Asian QRM. ;)

> When it's down real low, I use my  "SSB" antennas up on the 
> tower instead
> of the  "Satellite" antennas  which are on a short tower with  az-el
> rotors. It works out pretty good with horizontal polarization 
> only. I have

That's not a bad trick for horizon grazing passes.

> a  24 element beam on 432 and 12 element  KLM beam on 2 
> meters, up about 50
> feet. [But 5 watts though that length of coax would produce a 
> trickle of
> ERP. Plus the need for preamps on the downlink.] Have made 

Masthead mount an amplifier.  5W doesn't have demanding power requirements.
:)

> lots of QSO's
> that way, though. I guess my best DX was  J6 - St. Lucia  a 
> little over
> 4000 miles to the east on FO-29 and HC8N to the south, about 
> 3300 miles on
> UO-14. I had an "almost" QSO with GD4BEG on RS-15 once, we heard each

These are close to the theoretical limits of these birds.  Best I've managed
is arounf 4500km on UO-14 to Darwin or P29.  The limitation here is there's
not many exotic destinations that are active.  You basically get VK or ZL,
with the odd P29 or 3D2, if you're really lucky (I have worked P29, but
never managed to catch up with 3D2 on UO-14).

> other, but no QSO. John, K6YK [And I'll bet that John is one 
> of those that
> works AO-10 and 40 like a telephone ;-)

;)

> Go for RHCP; The only thing you'll lose out on is that, at 
> low elevation
> (say below
> 10 degrees [Which is what I want Rich]), signals get 
> scintillated to the
> opposite sense so an RHCP signal would get turned round ... 
> but its not
> usually by a complete turn. But a TPM has no gain - use a 
> beam. Richard W L
> Limebear G3RWL

I wouldn't say a TPM has no gain.  It does have some gain.  obviously, not a
real lot, because it's designed to have a fairly broad pattern.  But for low
working, long yagis are probably a better choice.  Try vertical, if that
suffers too many fades, go for crossed Yagis and put in a sense switching
relay to allow for the scintillation reversal.

> From all this, (for ON-THE-HORIZON LEO work) I get: use a vertical
> polarized 2 meter beam, save 3 db (my original thought) and 
> accept the rare
> times when the sat rcv antenna goes absolutely horizontal. Given the
> Russian 5 watt limit on VHF and up this seems the way to go 
> for transmit.

If possible, install amplifiers close to the antenna.  That will save on
coax loss and get your 5W where it's needed.  However, I routinely use less
power than that into smaller antennas. :)

> My potential shack is a second story location with tenna's on the flat
> (non-metal) roof. All other nearby buildings are single story 
> and there are
> NO trees in any direction for all least a kilometer! (Another 
> reason to
> keep the windload down!) The horizon is blocked by mountains in a few
> directions up to 2.5 degrees.

That's not bad.  I have to deal with horizons up to 10 or more degrees
(actually can be as bad as 50-70 degrees from the backyard, because of where
the houses are!).  Easiest solution?  Go portable. :)

> 
> Thanks to all. Too bad there is NO window of possibility to 
> work any of you
> on the LEO's, except maybe the PA. Maybe AO-10 and 40 in the future!

Don't rule anything out. ;-)  Anything's possible... with a bit of
ingenuity. :-)

> 
> Thx agn, 73, and cheers from finally white Siberia, O.J. 
> Lougheed, Irktusk

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