Hello I'm not sure if I have some "operator trouble" or equipment snafus. Running an IC1271A 10 watts to a homebrew 40 T helix via 45 feet of 1/2 hardline. With a questionable connector. Eight feet of LMR400 to the antenna. I can hear some you you guys, but my up link is a no go. I'm transmitting on 1268.700 +/- 20. Considering doppler what is your uplink freq? I also might have some questionable construction methods with my antenna. I suppose if this were easy everyone would be doing it!
-- 73 Bob W7LRD AMSAT member 28498 Seattle
Bob,
The Doppler runs something like +/- 25 KHz. From my measurements, and comments heard, there is an informal consensus that probably the real center of the uplink is more like 1268.703 or so. You need to be within about 5 KHz to get in well, and if you are running a lot of power, you can get by a bit further off. I am pretty well netted to the uplink, and required power ranges from 1-2 watts to 80 watts to get a good signal, depending on location, S/C orientation, and number of trees in the way. This using about 70' of Heliax to a 32 element M2.
Guys running without computer control to the TX drop out a lot. Other things to check are the pointing accuracy, which becomes more important with more directive arrays. One test worth doing, if the situation permits, is to use a Bird or similar wattmeter and measure the power directly at the antenna. I found a big problem that way once, and then worked backward toward the station to eventually find the bad connector. WI2W is getting in with a 10 element yagi and 10 watts, so while more EIRP is definitely better, it can be done.
Alan WA4SCA
Hi Bob,
Wow, that should work. I've got the same rig, 60' of hardline and about 7' of RG-8 at each end. The antenna is a 9-element Quagi from the ARRL Antenna Handbook, polarized horizontally.
The start of a pass is around 1268.670, climbing up to 1268.730 at the end of the pass. I generally don't get into the bird until it's around 20 degrees up, partly due to trees. The downlink side I have a 2x8 element Yagi with a preamp, and find that polarization changes during the pass, seemingly at random. I generally follow doppler by keying up and tuning around to find the edges where I get fuzzy, then center it. It just takes a second or two. I also find that my computer prediction is about 5khz low (so tune 5 khz higher than it says), but otherwise pretty accurate. Others have similar offsets in the 2-5 khz range. You don't seem to need the 67 hz tone (and it sounds a lot better without it!). My rotors and receive rig (Yaesu 736R) are computer controlled; I have to run the transmit side by hand.
Keep trying!
Greg KO6TH
----Original Message Follows---- From: w7lrd@comcast.net To: amsat-bb@amsat.org Subject: [amsat-bb] no go 1.2 on AO-51 Date: Thu, 21 Jun 2007 18:24:28 +0000
Hello I'm not sure if I have some "operator trouble" or equipment snafus. Running an IC1271A 10 watts to a homebrew 40 T helix via 45 feet of 1/2 hardline. With a questionable connector. Eight feet of LMR400 to the antenna. I can hear some you you guys, but my up link is a no go. I'm transmitting on 1268.700 +/- 20. Considering doppler what is your uplink freq? I also might have some questionable construction methods with my antenna. I suppose if this were easy everyone would be doing it!
-- 73 Bob W7LRD AMSAT member 28498 Seattle _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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participants (3)
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Alan P. Biddle -
Greg D. -
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