[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

R: helix location vs focus



Hi Greg KO6TH,

Read please "Dish Feeds for Mode S Reception" by Ed Krome, KA9LNV
published in Mode S the Book,chapter "The Helix" page 84

73" de i8CVS Domenico

----- Original Message -----
From: Greg D. <ko6th_greg@hotmail.com>
To: <amsat-bb@AMSAT.Org>
Sent: Friday, June 07, 2002 10:10 PM
Subject: Re: [amsat-bb] helix location vs focus


> Hi Dave,
>
> Right; I used tin foil, but same thing.  But the question
> I was answering was where to position the helix, with respect
> to the maximum-smoke point?
>
> Greg  KO6TH
>
>
> >From: Dave Guimont <dguimon1@san.rr.com>
> >To: "Greg D." <ko6th_greg@hotmail.com>
> >CC: amsat-bb@amsat.org
> >Subject: Re: [amsat-bb] helix location vs focus
> >Date: Thu, 06 Jun 2002 23:32:45 -0700
> >
> >
> >
> >>>   I read somewhere (can't remember) that you should place the
> >>>   bottom (i.e. feedpoint) of the helix at the focus of the dish.
> >>
> >>I seem to recall someone on this BB experimenting, and finding
> >>that the hot spot was at the end of the first turn for a simple
> >>helix.  My own experiments seem to put the hot spot at the mouth
> >>of the can, for "canned helix" antennas.
> >>
> >>The best thing to do is to create (or locate) a weak signal
> >>source, and adjust it for best signal.  Then, let the rest of
> >>us know where it is!
> >>
> >Hi Greg et al,
> >
> >Very simple to determine, and it is very close to that.  I've been
winding
> >and testing them since O13.
> >
> >Glue half a dozen ~1" mirrors scattered around the dish. I use them to
> >determine
> >the mounting length and approximate position for the helix.  Tune on a
> >steady
> >beacon, and adjust for max smoke.  Then point back at the sun and
> >inter-leave
> >a small piece of paper for the bright spot; hot, if u will....
> >
>
>
>
>
> _________________________________________________________________
> Join the world's largest e-mail service with MSN Hotmail.
> http://www.hotmail.com
>
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org


----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home