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Re: Cross boom length?



Thanks to all for their answers.
 Ed, your setup sounds  close to what I intend to do. I have a BBQ grill 
dish here for 2.4Ghz and then I'm working on homebrew  antennas for 70cm and 
2 meters. Neither will have near the boom length of your antennas. My main 
concern was enough seperation between the antennas.
 I was going by the concept of stacking monobanders on HF. If I remember 
correctly, a minimum of a quarter wavelength on the lowest frequency is 
usually used. for seperation distance.I wasn't sure if that applied to 
sattelite systems or not but judging by your experience 5 feet should be 
fine for my application.
Thanks and 73,
Michael, W4HIJ
----- Original Message ----- 
From: "Edward R. Cole" <al7eb@acsalaska.net>
To: <amsat-bb@amsat.org>
Sent: Saturday, March 18, 2006 4:18 PM
Subject: Re: [amsat-bb] Cross boom length?


> Although what Joe says is true,  the longer cross boom places the rotator
> under more mechanical stress from wind forces, since the antennas are on a
> longer lever arm (greater vector arm) from the center of rotation.
>
> I have used a 60-inch (5-ft) sched-80 aluminum cross boom with my Yaesu
> B5400 which supports an 18-foot long M2 436CP42 and a KLM-22C (about the
> same length as the M2) on the other end.  In the middle is a 33-inch dish
> for 2400 MHz.  I have not experienced any cross talk of the antennas in
> full-duplex mode-U, L or S.  I removed my 1268 equipment last summer and
> installed them inside my 2m eme array so that they could also be used for
> terrestrial communications on 1296.
>
> The satellite array is mounted on a radio shack tripod tower and sits 
> about
> 12-feet above the flat roof of my house:
> http://www.qsl.net/al7eb/sat.htm
>
> 73's Ed - KL7UW
>
> At 02:05 PM 3/18/2006 -0600, Gary \"Joe\" Mayfield wrote:
>>Longer is better - more isolation - more room for antennas.  That's why I
>>always recommend a 10 foot piece of steel tubing.
>>
>>73,
>>Joe
>>kk0sd
----
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