Re: [amsat-bb] BIGGER dish

[Ken Koster <n7ipb@xxxxxxxxxxxxxxxxx>]

On Thursday 25 July 2002 20:15, Bob V Johnson wrote:
> Hello
> I am currently using a primestar dish (26"X36"), a 3731AA downconverter
> with 5.5 turn helix feed.  I have a 1.2M primestar dish (48"X52"), I am
> thinking of using it, the following questions come to mind.

Sounds almost exactly like my setup.  1.2M primestar with a 5.5 turn helix, 
into a 3733 converter.  Rotors are the older Kenpro units which are lighter
duty than the G5400.

> 1.  how much more gain would I realize?

See Ed Coles response for this one.

> 2. what size helix for proper illumination?

Same one as you use for the smaller dish.  I've tried different numbers of
turns but around 5.5 to 6 seems to be about the best.

> 3. will my G5400 rotor take it, in addition to a 2M 8el and a 70cm 18 el?

I have mine mounted on the older Kenpro units and with counterweights they
seem to do just fine.  Mine is somewhat shielded from wind by being in my
back yard and only 6 feet off the ground, but so far it's not been a problem.
Of course I've only had it installed since May and haven't had any really 
nasty storms yet. I am careful to park it for least wind resistance when the 
wind comes up.

> 4. how much  more squint angle can I get?

Squint angle doesn't seem to be much of an issue, at least my experience is 
that if the Satellite is above the horizon and not blocked by nearby hills
or my neighbors house I copy the beacon at a solid S-9 or about 5-6 s-units
above the noise level.  Of course, near perigee all bets are off.

I was planning on getting a low noise preamp, but given the performance I 
see I'm not  sure it would add much.

> Any other information any of you might feel is pertinent.

Pictures at http://algedi.seatcp.net/~n7ipb

> 73...Bob...W7LRD
> Seattle, Wa.

Ken, N7IPB
Mount Vernon, WA

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