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@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: http://i238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/W0OQCHarnes...

Calculations to determine length of the two 70 Ohm matching cables and the 93 Ohm phasing cable: http://i238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/W0OQCcalcul...

Photo of KB2M's finished wiring harness: http://i238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/KB2MArrowma...

Photo of KB2M's RHCP 7x7 Arrow yagi on the mast: http://i238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/KB2MArrowon...

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

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