I heard a few passes of AO-51 in L/U mode. Most stations came in strong. I tried to get into the bird using about 8 watts out into a 23cm horizontal yagi on an elevation rotor. It was to no avail, though the bird was at 50 degree's and higher. I am working on a CP antenna for mode L.
Can those that worked this mode give me an idea of wattage, EIRP or antenna for Mode L that you are using. I was sure 7-10 watts would do from the Icom 910. However, it may have been the yagi and the lack of CP.
Thanks
Greg
N3MVF
Depending on the length of your feedline, you should have been audible at least. Doppler tuning is VERY important, are you set up for tuning the uplink?
As a reference, I started out on L/U last year with 10 watts, ~3db of feedline loss, and a 24 element horizontal loop yagi. I was ok at 20 degrees or higher, with bad fades. I added a 60w amp and am good from 5-10 degrees and up, with occasional fades noticeable.
73, Drew KO4MA
----- Original Message ----- From: [email protected] To: [email protected] Sent: Tuesday, November 25, 2008 9:37 PM Subject: [amsat-bb] AO-51 mode L/U
I heard a few passes of AO-51 in L/U mode. Most stations came in strong. I tried to get into the bird using about 8 watts out into a 23cm horizontal yagi on an elevation rotor. It was to no avail, though the bird was at 50 degree's and higher. I am working on a CP antenna for mode L.
Can those that worked this mode give me an idea of wattage, EIRP or antenna for Mode L that you are using. I was sure 7-10 watts would do from the Icom 910. However, it may have been the yagi and the lack of CP.
Thanks
Greg
N3MVF _______________________________________________ Sent via [email protected]. 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
Hi Greg,
I've not tried L/U this week, but in the past I have been able to get in with 10 watts from my ICOM 1271A to a homebrew 18 turn helix, with about 60' of hardline and between 5 and 10' of RG-214 or similar at each end, between the rig and the antenna. I have no idea what power actually reaches the antenna, but, between the cable and all the connectors, I expect it's only a couple of watts at the most. Trees definitely are a factor (can't shoot through them very well), and I am on an Az/El rotor system so I can aim at the satellite pretty well.
As Drew notes, Doppler shift is really a factor on the upper bands. You'll be spinning the dial constantly. I use my satellite tracking program (predict on my Linux system) to tell me what frequency I should be on. I haven't connected the rig to the computer yet, otherwise it would be automatically controlled.
Good luck,
Greg KO6TH
Date: Wed, 26 Nov 2008 02:37:35 +0000 From: [email protected] To: [email protected] Subject: [amsat-bb] AO-51 mode L/U
I heard a few passes of AO-51 in L/U mode. Most stations came in strong. I tried to get into the bird using about 8 watts out into a 23cm horizontal yagi on an elevation rotor. It was to no avail, though the bird was at 50 degree's and higher. I am working on a CP antenna for mode L.
Can those that worked this mode give me an idea of wattage, EIRP or antenna for Mode L that you are using. I was sure 7-10 watts would do from the Icom 910. However, it may have been the yagi and the lack of CP.
Thanks
Greg
N3MVF _______________________________________________ Sent via [email protected]. 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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After you get your computer control working, highly recommended for both you and the people you work, you will need to tweak or at least verify your uplink. Most ham gear is pretty good about frequency and stability, but the local oscillator frequencies may not be quite on, and few hams have digital counters which are highly accurate at a GHz or so. If accessible, the LO output can be measured, usually more accurately. Also, the rigs in the satellites drift a small amount.
What I have done is take advantage of times when I was the only one on mode LU or LS by changing the uplink by +/- 5 kHz at minimum usable TX power. Usually one will sound better than the other. So move in that direction 2-3 kHz and repeat, reducing the TX power as needed. You should be able to box the best uplink frequency quickly. Then you can either change the uplink frequency in your control program, or adjust the LO frequency stored in your program. I do the latter. Of course, always be alert for someone else wanting to use the bird.
I have a system roughly equivalent to Drew's and once I get out of the horizon clutter it only takes 5 watts or so for full quieting under most conditions.
Alan WA4SCA
participants (4)
-
Alan P. Biddle -
almetco＠comcast.net -
Andrew Glasbrenner -
Greg D.