Re: [amsat-bb] (no subject)

[K5OE@xxxxxxx]

Tony,
Great pictures... and so much work!  Thanks for sharing them.  I am sure they 
will give many people the incentive to build up something.  I see from some 
of your other pictures you have built lots of now-spare systems--I have a 
garage full of those also :-)  The helix with ring-reflector is very nice 
looking--those are especially nice for a compact portable system.  Mine 
worked just fine for UO-11, but as we all now know, UO-11 is much easier to 
hear than S2 SSB on AO-40.

You indicated the performance of the two systems was comparable.  The BIG 
question everyone will sit on the edge of their seat to hear is... (drum 
roll, please):  can you swap either the UEK or the TSI d/c from one antenna 
to the other?  With that comparison you will get a narrower comparison of the 
dish+feed options.  I never had a 3733+dipole feed up to compare to the 
helix+cup feed.

A neat idea would be to take the stock TSI system supplied by K5GNA (dish + 
3733), remove the dipole feed, and add an extension of some type to fit a 
helix+cup right at the calculated focus.  The feed line would run up the 
center of the helix--coaxially.  With a wire mesh screen on the dish, a 
plug-and-play feed replacement like this would be a popular item, I am sure, 
to gain 2.5 - 3 dB.  
73,
Jerry, K5OE

Kc2hax@aol.com writes:

> Hi Folks!
>  I have uploaded new photos of the DHSatellite 32" (80 cm) prime focus dish 
> in 
>  the web-site.
>  these are the two links:
>  http://www.qsl.net/kc2hax/ant/antenna.htm
>  http://www.qsl.net/kc2hax/ant/expant.htm
>  The feed is an helix (3.25 turns in a coffee can feedhorn). The back of 
the 
>  can is 4 cm behind the focus (focus is 27 cm and back of can is at 31) and 
>  the sides of the can/feedhorn have been calculated to minimize spillover 
> from 
>  the dish edge's as per Jerry K5OE paper in the proceedings of the AMSAT-NA 
>  Space Symposium.
>  Converter is a UEK2000SAT. I was expecting this system (circularly 
polarized)
>  
>  to be superior to my TSI 3733 and Connifer (now Andrews) BBQ (linear pol). 
>  But after expending long hours listening during today's orbit and doing 
side 
> 
>  by side sujective listening comparisons with different rigs... I still 
> prefer 
>  the modified TSI-Connifer combo (I think I hitted the sweetspot of the TSI 
>  when I made the mod by K5GNA and fitted it in the focus of the Connifer 
>  because this system performs like a champ). At this point, I cannot say 
that 
> 
>  there are significative differences among the two systems but the modified 
>  TSI-Connifer are real value for money. Wish I had a G3RUH patch!
>  
>  Best 73 de antonio, KC2HAX / EA4LE
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