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Re: f/d ratio Scott - Gil - Dr. Jim



This past weekend I put up a primestar dish on my 20' tower. For AZ I am
using a HyGain Ham III. For elevation I am using a regular TVRO dish
actuator. I did not use a counter balance on the dish as the actuator itself
is almost equal weight. For a mount I used a heavy duty door hinge ( 8-0= )
and two pieces of 5"X10",  3/8" aluminum stock. The metal structure that
bolts directly to the back of the dish has a flat surface that lines up with
the center of the radiated signal from the dish and one of the plates was
mounted to this.

The lash up is pretty crude and lewd but, if I can get a crack at the
satellite after RUDAK has finished with it, I expect it to work much better
than the BBQ grille I was using. These actuators are very strong, being
designed to push a 10' dish around.

>From what playing I have done with the Link Calculator proram, the antenna
is where all your efforts have to go, after you have the required pre-amp
installed. The spreadsheet thing says I should hear the noise floor at the
better squint angles. Here's hoping...

----- Original Message -----
From: Gunther Meisse <gjmouse@neo.rr.com>
To: <amsat-bb@AMSAT.Org>
Sent: Sunday, July 29, 2001 9:57 PM
Subject: [amsat-bb] f/d ratio Scott - Gil - Dr. Jim


> Thank you to: Scott, Gil and Dr. Jim. This -bb is wonderful! Well, I have
> the old 5Ghz feed and so it was very easy once I knew what to do with the
> dimensions. The answer: 0.37. I am in good shape. Dr., I love your style.
Do
> the math, or just use the ruler and real waves hitting the dish. Hands
on...
> One will never forget the answer to this question.
>
> I know the high squint is very detrimental to to S Band downlink. However,
> even with squints of 5-15, I am only seeing S8.5 to S 9 on the beacon and
of
> course the QSOs are 10 db down, which puts them to close to my noise floor
> at S 5 -5.5. I calibrated my S meter, and while not linear, it is
basically
> 2.75db per S unit. My ears are not what they used to be (I am in the
> commercial broadcast business--Earphones for to many years)plus I like
> quality audio. I want at least 10-12db of quieting. SO, my 60cm dish with
> UEK-3000 can not be improved upon. I need more wave fronts pinging on my
> feed. This old dish, with the Patch feed will, I hope, give me ears as big
> as my mouth.Hi
> The next issue is of course az/el steering. My first plan was to use a
> second G-5500 slaved to the original which is doing my uplink. As you so
> aptly point out, I am trading one problem for another. At first glance,
> weight and torque do not appear to be a problem with a well
counterbalanced
> dish. STOPPING at the correct place is another matter. Well, this will
give
> me something to ponder  this week.
> Again thanks for all your help.
> 73
> Gunther Meisse
> W8GSM
>
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>

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