[amsat-bb] Re: How to make phasing cable for 440 MHz Arrow II

Doug Faunt N6TQS +1-510-655-8604 faunt at panix.com
Sun Dec 2 14:58:34 PST 2007

It'd be really nice if someone with the tools, test equipment and
knowhow would make such cables for us.  I've ended up with too many
expensive cables that were too short, just too long to be not
reusable, or fell apart too soon.

But it's time to start thinking about them again.

73, doug

   Date: Sun, 02 Dec 2007 13:27:46 -0600
   From: Wayne Estes <w9ae at charter.net>

   Click the links below to see how KB2M modified the 7+7 Arrow 70cm yagi 
   to be circular polarized.

   Hand-written diagram from W0OQC:

   Calculations to determine length of the two 70 Ohm matching cables and 
   the 93 Ohm phasing cable:

   Photo of KB2M's finished wiring harness:

   Photo of KB2M's RHCP 7x7 Arrow yagi on the mast:

   Note that this was done as a portable uplink antenna for AO40.  I can't 
   think of any currently functioning ham satellites that would really need 
   a RHCP 70cm antenna.

   The impedance matching cables are 3/4 wavelength long.  That makes the 
   dimensional tolerances 1/3 as critical compared to making 1/4 wavelength 
   cables.  The phasing cable is 1/4 wavelength long for obvious reasons. 
   Also note that the dimensions should be measured from the center of the 
   Tee to the end of the pin on the BNC connectors (connector and Tee 
   contribute to the electrical length).

   Wayne Estes W9AE
   Oakland, Oregon, USA, CN83ik

   Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
   Not an AMSAT-NA member? Join now to support the amateur satellite program!
   Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list