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RE: Survey: L and S minimums

Report from city of San Francisco:
at about 12:30Z (range to AO-40 about 33,000 km)
(1) "Golden Rod" RHCP antenna,  built for commercial TV service at 2.5 Ghz.
      Has about 18 GB gain at 2.4 G.    SSB UEK2000 converter at antenna.
      Some QSB, but sigs several S units above noise.
(2) uplink- 1269 Mhz about 10W at antenna,  a KLM 1.2-44LBX (linear polz.)
with about 18DB gain.
     My CW sig at about the beacon level.   I get desense above the 10W
    Tried 435 Mhz uplink, but above about 15W, I really desense sigs, so did
not copy my sig.

I operated mode L on OSCAR-13 and have been looking forward to it's
successor.   Really great to hear a high-orbit bird again.   Now I need to
get a filter at the antenna to hopefully reduce the desense.      A big
problem here in the urban environment in the number of sigs on 2.4 G from
the low-power unlicensed stuff.    Mostly spread-spectrum from telephones
and wireless LANs I suspect.
I noticed noise here on the band is highly a function of time of day.   For
example at 12:30Z (05:30 local) it's pretty quiet, but by 07:00 local, lots
of "buzzes and pops" !!  Don't know what I can do about the in-band garbage.

Kit Brown, WB6QVU, San Francisco CA

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of Ed Krome
Sent: Saturday, May 05, 2001 08:38
To: Amsat BBS
Subject: [amsat-bb] Survey: L and S minimums

Hi, All:
        Wow, AO40 was terrific on this first morning of transponder
operation! After almost 10 years, what a thrill! Heartfelt thanks to all
those who have busted their backends for so many years. You are

        I would like some information. I have updated "Mode S: The Book"
and it will be available at Dayton and I still have one shot to add
information before it's printed (really!). So, of all you hi-freaks (pun?)
who were operating modes U/S and L/S today, please write back to me:
1) S-band downlink antenna size: WD4FAB was using a homebrew 16 turn helix
and SSB UEK2000 converter and was hearing just fine. Anybody else using
tiny antennas with good results? Most people I talked to were using small
dishes (the truncated-parabola, "barbeque grill" style). Hearing was
generally quite good (especially toward the end of the period). What were
you all using?
How were the downlinks in Europe at earlier MA's?
2) L-band uplink: those who experimented with 1269 MHz uplink, how much
power and what antennas were you using? How were your signals? I had quite
good reports with my 6-foot loop yagi (cut for 1296, not 1269) and maybe 30
watts (don't know exactly). (Which, incidently, I found surprising because
I was desensing myself almost completely. It was so bad, I had a lot of
trouble finding my own downlink with L-up. The fun of homebrew.).

Let me know!


Ed Krome K9EK
editor/author "Mode S: The Book;   2001 Update for AO-40"
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