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General AO-40 Observations



bb members:

I am going to share some observations on the AO-40 bird. I would like to
know if you concur on any of these. If you have general thoughts about my
thoughts, please speak up.

	1. 70cm up link: I read that the up link is RHCP. I do substantially better
with LHCP, using an m2 30 element crossed yagi and power from 20 to 100
watts TPO.

	2. When the bird is east  of my location I do very well getting great 5/7
5/8 reports, and often need to power down to keep the girl in her cave.
When the bird is west of my location, even with a full 100 watts TPO the
signal stinks. I also hear very few if any other operators on her. The MB is
still strong, S-7 above the noise floor thus, the only difference
(east-to-west) is the Up-link rx antenna position in relation to me.

	3.  23 cm Up-link: I run up to 80 watts TPO on the 23cm uplink always RHCP.
I use a 60cm dish or a 25 turn RHCP helix, all with wonderful VSWR. I can
barely make the bird. The result is very much like of the 70cm tests when I
reverse the polarization. The people I have spoken to on the bird (L-Band up
/ S Down) have generally been using a liner polarized L-Band antenna. Many
with good results. None with as much power as I am running. Now, I must tell
you that my helix antennas are made with 3m 1/4" copper tape. Could such a
design be worthless? Good tune-up, poor radiation? I do know the concept
works, since I have a 1/4" 3m tape feed for S-band on a 60cm downlink dish
and it works great.

Your input appreciated.

73
Gunther Meisse
W8GSM
AMSAT LM: 594

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