SO-50 uses a corner mounted single UHF whip for the downlink, so it is linearly polarized, and is often shielded by the body of the spacecraft. It also runs about 250mw, which is pretty low. By comparision FO-29 is circularly polarized. Operating portable on SO-50 it is extremely beneficial to be able to twist a yagi to match or peak polarity for best signal. A typical home station overcomes this with gain and circular polarity.

As far as frequency, SO-50 has developed a shift in the downlink frequency that comes and goes. On a busy pass you can use the AFC function on the 910 to keep the downlink centered, or you can do as I have by setting up a series of entries in the doppler.sqf file moving the downlink frequency up and down in 2.5 khz steps. During a pass I will cycle through these to find the best one to match the frequency of the day.

I hope these hints help...

73, Drew KO4MA

-----Original Message-----

From: Les Rayburn les@highnoonfilm.com Sent: Sep 19, 2013 1:23 PM To: AMSAT Mailing List amsat-bb@amsat.org, starcom-bb@star-com.net Subject: [amsat-bb] SO-50, IC-910H, and Sat PC32 Issues

Before I ask again for assistance, I'd like to say that I've read the "manual" for both the software and the rig, experimented, and tested on my own trying to resolve these issues. This includes staying up well past midnight so that I can run tests on the bird without bothering other users too much.

Here, briefly is a description of my station, and the issues I'm experiencing. Any assistance or advice in resolving the problem would be gratefully accepted:

Running an Icom IC-910H into antennas in the attic. The 432 antenna is an Arrow 7 element Yagi, mounted at a fixed elevation of 25 degrees. The 2 Meter antenna is a 6 element K1FO Yagi, mounted horizontal. Both can be rotated on the stack in azimuth only. Feedline is 75' foot runs of 1/2" hardline with antennas mounted in the attic.

The 432 antenna has an ARR mast mount pre-amp, while the 2 Meter antenna has an SSB Electronics mast mount pre-amp. Performance on FO-29, VO-52 is fair to good. High elevation passes on all satellites seem to give me reception problems, but down nearer the horizon things are good. Hoping to upgrade to AZ/EL in the near future.

I've learned how to deal with Doppler on the other birds, and generally can used the stored corrections in SATPC32, or adjust it on the fly using the software to hear my own downlink well, and work other stations.

SO-50 ISSUES

However, on FM I continue to struggle.

A.) Reception is poor. Especially high elevation passes. B.) Successful reception of other stations requires adjusting the RIT control on the rig. Often to "plus" 5 KHz and sometimes to somewhere in between 0 and +5 Khz. C.) Switching the rig to FM Narrow mode helped, but did not resolve the problem. D.) Attempting to adjust for Doppler using the software control doesn't seem to help much. E.) I can only rarely hear my own downlink on this satellite, even in the middle of the night when the bird is empty. F.) Numerous reports of others calling me without success, even though I'm getting into the bird fine.

I realize that polarity is an issue with all satellites. Signals arrive out of phase, and I have no way to compensate. Also having a fixed elevation is a problem, and explains the poor performance at high elevation. But I fail to understand why the system seems to work well on other birds, but not SO-50. What am I missing?

--

73,

Les Rayburn, N1LF 121 Mayfair Park Maylene, AL 35114 EM63nf

6M VUCC #1712 AMSAT #38965 Grid Bandits #222 Southeastern VHF Society Central States VHF Society Life Member Six Club #2484

Active on 6 Meters thru 1296, 10GHz & Light

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