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RE: Primestar dishes



I have picked up 6 of these.  Dave at the Olde Antenna Lab is building me
feeds for various MW bands.  He pulls the old electronics and tosses them,
drills out the old feed, then adds a probe and a coupler to pull the signal
out through an N connector.  We are still experimenting, but see no reason
why this won't work.  For L or S you would need to do some mechanical work
to replace the Ku feed with one for the right band, but this doesn't seem
to tough.

On the other hand these are big and heavy.  A thin aluminum 'snow coaster'
or one of James' lamp shades might be easier to mount and turn, and work
just about as well.

On the other other hand, if all is successful with P3d and it reaches an
orbit like that proposed you could bolt a PrimeStar dish on a post and not
have to worry about rotors.  Or, since they are free, put feeds on two or
three bolted on posts pointing E, W and whatever, cable to a single LNA
through a switch, and switch in the one pointed at the bird.  I have 5
acres.  I could have 20 of them :-)

jw
wd0e@amsat.org
jim@coloradosatellite.com

>
> 
>> Since the Primestar system used a domestic Ku band satellite in the FSS 
>> service, the dish as it stands has a feed built for linear polarization
and 
>> a minimum bandwidth of 11.7 Ghz to 12.2 Ghz.  My guess is that it will 
>> probably work pretty good down to high end of 10 Ghz. Unfortunately, the 
>> LNB and feed are probably integrated to form an LNBF, meaning that you
just 
>> cant remove the LNB. It may be possible to modify the LNBF for amature 
>> frequencies.
>
>There may be more than one version of the Primestar systems, but the one I
picked up in 
>the dump seems to have an LNB that will come off the feedhorn part,
however it is not a 
>standard lnb with rectangular flange, but instead a cylindrical one.  I
haven't taken it 
>apart yet, but I did try it out on regular KU sats to make sure it worked.
 Of course, 
>the output  of the lnbf for the 11700-12200 is down at 950-1450, ie
LO=10750, so it isn't 
>clear to me that perhaps it might work better at the low end of the band
since the 
>difference frequencies are closer to that at which the IF amps are
optimized at.  Ie 
>because of the LO freq I wouldn't expect it to work at all up near that
freq, but it 
>might work when you got further away from the LO.
>
>> There is no reason the Primestar antennas will not work on S band,
provided 
>> an appropriate feed can be worked out. Two things are going to make that a 
>> little difficult. The first is that the antenna is elliptical, so the feed 
>> needs to have an asymetric illumination pattern.
>
>Again, I think there must be two types of Primestar dishes out there.
While the one I 
>have indeed has an offset feed, the dish itself seems to be circular, ie a
regular 
>parabolic shape. Ie it could be used with the Primestar feed, which has an
eliptical 
>opening, or with a circular feed at the prime focus.  I have seen other
Primestar dishes 
>that have non-circular dishes, which also probably have a different LNBF.
>   In any event, these things are showing up in the trash all over the
country, and at a 
>minimum they can be used to pick up conventional KU TVRO  since you can
pick up TVRO 
>receivers very cheaply now too. Seems a shame for them to go to waste.
>
>
>
>
> 
>************************************
>*    Bill Jones   Sweden Maine     *
>* wejones@megalink.net             *
>* http://www.megalink.net/~wejones *
>************************************
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