Re: [amsat-bb] Direct Tv Dish

["Edward R. Cole" <al7eb@xxxxxxxxxxxxx>]

At 09:20 AM 2/3/2003 -0600, Jon Ogden wrote:
>on 2/3/03 8:15 AM, Art Goldman at aegoldm@lts.ncsc.mil wrote:
>
>> A friend gave me a Direct TV dish to try on AO-40.
>> 
>> So, I bent a piece of 1/8" aluminum bar to match the
>> mounting angles
>> of the original feed assembly, and have a TSI3731 with a
>> homemade patch
>> antenna attached, ready to pipe clamp to the mount.
>> 
>> Has anyone else done this and determined the optimum
>> distance from the patch to the dish surface?
>
>Art, 
>
>AFAIK, the focal point of the dish doesn't change with frequency.  So put
>the patch at the same point as the direct TV LNB feed.
>
>Let us know how it works.  I have one that has been sitting in a box in my
>garage for several years now.  I bought it to use on S-band before I got my
>BBQ dish.  According to what I know, the 18" dishes are a little to low in
>gain for good use on S-band.
>
>They would make a perfect C band and X band up/down antenna, but
>unfortunately, those components don't work any more on AO-40.
>
>73,
>
>Jon
>NA9D
>
>-------------------------------------
>Jon Ogden
>NA9D (ex: KE9NA)

Art,

Ditto on Jon's advice.  I tried an 18-inch DSS dish initially with a bare
Drake and got dismal results (mainly because to the Drakes poor NF).  I
used the original support hardware with a helix feed (that feed now is on
my 33-inch "Dish Net" offset dish working fine).  The dish will be 6 dB
less gain than what I am currently using.  You should hear the beacon OK
but I htink you will be disappointed for hearing stations to work.  Not
sure how good the  TSI3731 is by itself.  The 18-inch dish will require as
good a NF as you can get.

Ditto also on JOn's comment on mode-C/X.  Hoping a future satellite will
have X-band downlink.

----
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