Re: [amsat-bb] dual feed problems

[K5OE@xxxxxxx]

Quite a few AO-40 ops run dual feeds of one kind or another. Besides Charlie's, Howard's, and Robert's sites referenced below, I also recall seeing recently a VK4 (sorry, I forget the rest of the call) with a large dish and a combo helix-patch setup.  I also spoke to JA0BBW, Cyo, the other night on AO-40 and he was using a 1.2 m dish with a dual feed.  I had a dual-helix design up last year for a short while (also a 4' dish), but just recently put the dish back up with a dual-patch feed.  I confirm the 3731's insensitivity to L-band harmonics.

I presented a paper at the 2002 AMSAT-NA Symposium on dual-band feeds.  I don't have that paper on-line but you can see the Field Day antenna we used on my web site on the "Patch Feeds" page at the bottom:  http://members.aol.com/k5oe

Finally, the Jan/Feb AMSAT Journal will have an article that should be right up your alley:  "Build A No-Tune Dual-Band Patch Feed for Mode L/S."
73,
Jerry, K5OE 


In a message dated 1/4/2003 4:01:09 PM Eastern Standard Time, howard@howardlong.com writes:

> 
> 
> JC
> 
> > It would be neat to be able to add a dual band (L/S) feed and operate just
> > off the one dish, but I suspect the desense would be too much of a
> problem,
> > not to mention possibly blowing out the 2.4 preamp.
> 
> Yes.
> 
> http://www.g3wdg.free-online.co.uk/dual.htm
> http://www.ultimatecharger.com/dish.html
> http://www.g6lvb.com/g6lvb_shack_spring_2002.htm
> 
> The two methods so far seem to be use of either the G3WDG filters, or the
> AIDC 3731 downconverter. According to Robert W0LMD the 3731 d/c amazingly
> provides sufficient out of band desense to allow it to be used with a dual
> band L/S patch feed.
> 
> 73 Howard G6LVB
> 
> 
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