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Author Topic: AO-40 downlink on S2  (Read 241 times)
N0IDX
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Posts: 3




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« on: November 10, 2001, 08:04:32 PM »

I have been working very hard on trying to get a 2.4 gig. downlink receive for AO-40. My equipment consists of a FT-847. I have other antennas I won't get into.
The uplink is a 40 ele. 440 M2. It smokes! The problem is my downlink. I'm using a Pacific Wireless 2.4-2.5 3 foot 24 db. dish with passive dipole to a Transystem 3733 downconverter mod by K5GNA. I changed the original dipole to a N-male to accept the dish's dipole. It is on a azimuth elevation system with the 44 ele. yagi. My downlink signals are barely above the noise floor. The downconverter is mounted near the antenna and fed via 75 ohm coax to a voltage inserter near the shack. I tried a 6 db pad in an attempt to drop the noise floor. Still, the signals are barely above the noise. I'm thinking of trying a 2.4 gig. preamp between the dipole and the downconverter. Am I kicking a dead horse or what should I try?

HELP!
Glenn
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KC7YRN
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Posts: 161




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« Reply #1 on: November 11, 2001, 11:02:30 AM »

How near is "near the antenna"?

The numbers for coax losses at 2.4GHz are staggering.
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W9GB
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Posts: 2626




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« Reply #2 on: November 12, 2001, 12:54:41 AM »

Glenn -

You might want to cross post on amsat-bb@amsat.org

S-2 is a few dB less than S-1 (AO-40 parabolic dish), even though S-2 is a 50 watt transmitter into a Helix.

Some users have added screen mesh to reflector others that built a small helix to achieve a few more dB

w9gb
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