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ao-40 U/S system description DL0WH



Hi Folks,
here my system description of our U/S station at local clubstation DL0WH
in Weinheim Germany:

RX:
30 wind. helix from WIMO, about 3 ft. length and 16dB Gain with
UEK-3000SAT from SSB electronics, 30m cheapest RG-58, IC-821      
produces about S7 beacon signal at 50000 km distance, noise level S1

TX:
IC-821 with 30 m H100 into 2x15el stacked yagi (hor. polarized). 35
watts HF triggers LEILA at good squint at 50000km distance, 5-10 W
sufficient, 15-20 W produces stable S5 ssb-signal. later on at worse
squint angles (but smaller distance) even 35W won't trigger LEILA, but
15 W is still ok!

hope this one helps with setting up any new station.
My conclusion:

on U-uplink, almost any station will work.. power is small and antennas
are moderate.

on S-downlink, the UEK-3000 is doing very good with cheap lossy cable
because of high gain. It has very good sensitivity and is weatherproof.
Only drawback is price.. 8(
Mode-S antenna is 30 Windings helix. As from earlier postings this seems
to be the practical limit (about 3 ft.). In combination with the
UEK-3000 it is more than sufficient for a stable signal. In comparision
to a dish, it offers less cross section for windload (we have some nasty
storms in fall..) and not so narrow beamwidth for easier tracking. 
Drawback for this specific WIMO helix as far as I see is the rectangular
aluminum support tube: compared with the diameter of the helix, it's
probably too big. Improvement should be possible by replacing with a
microwave inert material (perhaps glassfiber?).

Any comments welcome.
73s Achim, DH2VA
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