[amsat-bb] Re: Re; Homebrew Polarity Switch

[i8cvs]

Hi Amsat's

For a homebrew polarity switch I suggest to read my article:
"Switching Four Polarizations on a 70 cm Crossed Yagi"

Part-1 in AMSAT Journal March/April 2007
Part-2 in AMSAT Journal May/June 2007

The above switching circuit allove to switch 4 polarizations V-H-RHCP and
LHCP on a crossed yagi having the elements spaced 1/4 wavelenght over the
boom and dimension of the feeding and delay lines can be scaled for 144 MHz
or any other band.

If someone is interested on it I can send a zipped pdf file of both the
above articles.

73" de

i8CVS Domenico

----- Original Message -----
From: "Art McBride" <kc6uqh at cox.net>
To: "'Nick/KB1RVT'" <kb1rvt at amsat.org>; <amsat-bb at amsat.org>
Sent: Saturday, July 31, 2010 6:14 PM
Subject: [amsat-bb] Re: Re; Homebrew Polarity Switch


> Nick,
> The circuit you referred to can be simplified. The two 1/4 wave 75 Ohm
coax
> sections match the two antennas to 50 Ohms. A 1/4 50 ohm line will delay
the
> signal by 90 degrees for circular polarization. The opposite rotation is
> accomplished by adding of a 1/2 wave 50 ohm section to delay one side by
180
> degrees. Further simplification when using crossed Yagi's is to space one
> Yagi a 1/4 wave behind the other and use only the 1/2 wave section.
> The end result is to have one antenna lead or lag by 90 degrees for RH or
LH
> rotation.
> To make this work both antennas must be the same electrically and any feed
> line after the matching sections must be identical lengths to the
antennas.
> All wavelength calculations use 2952/frequency in MHz times the VP of the
> coax for a 1/4 wave in inches. Multiply by 2 for 1/2 wave.
> Experiment and build your own.
> Amateur radio is learning by doing!
>
> Art, KC6UQH
>
> -----Original Message-----
> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
> Behalf Of Daniel "Nick" Kucij
> Sent: Thursday, July 29, 2010 9:11 AM
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] Re; Homebrew Polarity Switch
>
> > If anyone can point me in the right direction to find this item I
> > would
> > appreciate it.  Additionally, if it is something that I could
> > fabricate and
> > there is good info available online, please forward any appropriate
> > links to
> > me.
> >
> >
>
>
> David,
>
> PA3GUO has described a homebrew switch on his website,
> http://www.pa3guo.com/
>      Click on Antennas, then scroll to the Polarity Switch button.
>
> Nick KB1RVT
>
>
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