[amsat-bb] Re: AMSAT-BB Digest, Vol 3, Issue 239
rnutter at networkref.com
Mon May 12 13:17:03 PDT 2008
I am using a "budget" rotor from Channel Master for my current setup.
Is that strong enough to support an elevation rotor or do I need to save
up some $$$ and get an AZ/EL rotor ? It looks like Yaesu is the only
option I can find. Are there others that I should look at ?
John Kopala wrote:
> Been there, Done that. I am using a Directive Systems Looper antenna for
> 1.2 GHz. With the setup I have, I chose a 6 foot long version with a 30
> degree beamwidth rather than the 12 foot long antenna. It works quite well
> when AO-51 is put in L/U mode as was done several months back for channel B.
> You can check out my satellite antenna setup on QRZ.
> I am using the IC-910 with the 1.2 GHz module. Works great. Figure about
> half of your output will ever reach the antenna. I selected Belden 9913F7
> ultraflex cable which is ideal for my installation. Keep the runs as short
> as possible. Probably better, if it works for you, would be LMR-400 or 600
> or hardline.
> For a given length CP Yagi, the gain of the antenna is going to increase as
> the frequency increases (more elements, etc) and beamwidth of the antenna is
> going to become more narrow. So pointing the antenna accurately becomes a
> more significant factor. It's time to go out and buy the elevation rotor.
> You'll find that it is worth every penny you put into it. A beamwidth of 30
> degrees on 1.2 GHz gives the half power points as 15 degrees either side of
> the antenna position. You don't really want to be 15 degrees off. You want
> to keep the satellite well within the main lobe of the antenna. At 1.2 GHz,
> starting with 10 watts, figure half of that gets to the antenna. You don't
> want to throw away half or all of what's left because the antenna isn't
> pointed at the satellite. Elevation control will also reduce your power
> requirements on all of your uplinks.
> Date: Sun, 11 May 2008 20:49:23 -0500
> From: Ronald Nutter <rnutter at networkref.com>
> Subject: [amsat-bb] Suggestions for Mode L antenna
> To: amsat-bb at amsat.org
> Message-ID: <4827A223.6020304 at networkref.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> I am considering purchasing the 1.2 ghz module for my IC-910H. For my
> satellite work, I have my antennas angled at about 20 degrees since I
> dont have an az/el rotor. This setup worked reasonably well with Mode S
> this weekend. What are my chances to be able to work Mode L with this
> kind of setup ? Also, I would appreciate any suggestions for an antenna
> that I could use. With only 10 watts, I am not expecting a great signal
> but I would hope to have at least a readable signal. Also, would
> appreciate any suggestions as to coax/feedline that I should look at
> buying ?
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