[Moon-Net] Prime-focus vs. Offset-dish

serge ve1kg at eastlink.ca
Wed Nov 23 22:55:47 CET 2016

Hi Rex thank you I have been following what you have been doing on 10Ghz 
with small dishes & very low power.pretty amazing. As to the offset here i 
have a 18"  Dish to watch one of the US satellite * we are so far east That 
the satellite is about 4 degrees above horizon & my dish is pointing to the 
ground to get reception. It appears than  a prime focus dish is easier to 
handle but you seem to do well on 10Ghz Rex. I would imagine tracking must 
be tough so if your offset is 23 degrees then 90 degrees is only 67 degrees 
elevation with your dish. ON & ON
Thank you again for your suggestions.
----- Original Message ----- 
From: "Rex Moncur" <rmoncur at bigpond.net.au>
To: "'serge'" <ve1kg at eastlink.ca>; <dl7yc at snafu.de>; 
<moon-net at mailman.pe1itr.com>
Sent: Wednesday, November 23, 2016 7:56 PM
Subject: RE: [Moon-Net] Prime-focus vs. Offset-dish

> Hi Serge
> One issue with offset dishes that has not been discussed so far is how to
> mount them in a way that allows you to beam low at the horizon.  I notice
> that often people with offset dishes cannot work down to zero degrees as 
> the
> bottom of the dish comes back against the vertical part of the mount. 
> This
> can be resolved by putting the feed at the top but then the feed is more
> difficult to access.
> Another solution is to have the vertical mounting extended into an L shape
> to mount the centre of the offset dish so it is clear of the vertical part
> of the mount when beaming at low elevations.  The downside of this it that
> all the weight is leveraged to one side of the mount and you need a much
> stronger mount to maintain accurate elevation.
> 73 Rex VK7MO

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