[amsat-bb] Re: AMSAT-BB Digest, Vol 3, Issue 239

Ronald Nutter 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:
> Ron,
> 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 ?
> Thanks,
> Ron
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