[NLRS] 10 GHz antenna party

[Baker, Donn B]

Doug,

I think it depends on what you have available for a dish and feed horn.
Making an SMA/Waveguide transition in WR90 is easy !  Not sure that its
easier than converting a Chaparrel feedhorn, though.

For converting a Chaparrel horn, I don't think the "single hole" SMA
connector is the way to go.  The metal in the feed will be too thin to
support the SMA*.  I've used the standard 4-hole chassis mount connector
just fine. Obviously, a two-hole works, too.

(* I would NOT attempt to use the "bulkhead" style connector... the one with
a flange on one side and a nut on the other.  It won't conform to the curve
of the feed waveguide and will leave HUGE "bump" in the guide.  The threaded
only type, with a jam-nut on the out side MIGHT work, but like I said, there
really won't be enough metal in the wall of the guide to support it
correctly.
Having said all that, I do have a 1/4-36 tap (SMA threads) if you want to
try it that way.)

I expect you will have to drill out the waveguide.  I have NOT converted a
Sony dish... I did do an RCA one.  I don't remember the original I.D. of the
guide, but I did have to drill it out.  I went to 0.75" which provides a
cutoff frequency of around 9.25 GHz.  That diameter was as big as I could go
and still have some metal left in the walls.  I would have preferred a
little larger, but it works just fine.  Used a 4-hole SMA mounted with the
diagonal corners.  There was enough metal left to tap 2-56 without any
problem.  The 1/4" long bolts had to be shimmed on the top side of the
connector to bring the ends flush with the inside of the waveguide.

We'll talk at Breakfast tomorrow.  If you can, bring the feedhorn with you.

73 Donn
WA2VOI/0


>-----Original Message-----
>From: Doug Reed [mailto:n0nas@amsat.org]
>Sent: Friday, July 11, 2003 7:27 AM
>To: nlrs@mailman.qth.net
>Subject: [NLRS] 10 GHz antenna party
>

SNIP

>I expect the easiest option is to modify the Sony LNA feed 
>horn by adding
>an SMA as a feed. And I think there was also some discussion 
>about drilling
>out the throat of the Sony horn to make it larger. One problem 
>is that I
>don't have any single hole mount SMA connectors. 
>
>