[NLRS] DirecTV/Cal Amp feed

[Dr. Gerald N. Johnson]

On Thu, 2009-10-01 at 11:59 -0500, David Palm wrote:
> 
> This is a long shot, but is there anything that can be done with this thing
> for ham usage?  Somebody just gave me a few of them:
> 
> http://www.sadoun.com/Sat/Products/DirecTV/Cal-Amp-150517-DSS-Dual-LNBF.htm

Not a long shot at all. Most of the DTV dishes on Buck Hill ten days ago
used one of those with modifications for the feed. There is also a nice
little PC board that comes out while making it into a feed that has at
least 4 low noise 12 GHz FETs. The one I took apart had no tuning until
just before the mixer so will be broadband and could with a bit of
repackaging make a workable 10 GHz preamp.

The feed horn itself has a tapered waveguide with circular polarization
septum. Mine (a new one from a Direct TV distributor) had a dielectric
polarization septum. I took that out, then ran a 3/4" drill through the
waveguide to open it up and make it straight. Then I plumbed in a probe
from an article about using 3/4" copper water pipe at 10 GHz. Some also
add tuning screws, I didn't have the time to do that. Between an old
transverter with not preamp and low transmit power, I had a tough time
making the longest distance contacts from Buck Hill, but I did make the
long paths to some of the rovers out at 253 km. 

Yup they work, I've not seen documentation on using them, might have
saved me doing some invention. Donn and Scott reported modifying many.

73, Jerry, K0CQ