On Mon, 2009-07-13 at 14:51 +0000, w6zkh@comcast.net wrote:
I recently obtained a pair of KLM yagi's for satellite work. They both have the KLM polarity switching box mounted and wired up. Since I havent put them up yet, and not well versed in the subject, I got out my ohm meter just to see what was what on this item. I noticed that both driven elements have continuty to the center pin of the coax at the same time. I was under the impression that the relay switched back and forth the driven elements to give either RH or LH polarity. I havent applied the 12 volts to the box yet to check that out, but was just curious. One thing I have noticed while using the downlink yagi is that I get very little fade due to polarity when I turn the antenna. I hope that is a good thing?? I havent checked the uplink yagi to see if it has the same results.
I hope someone can enlighten me abit.
If it's circular-polarised then both elements should be wired, with one going through a 1/4-wavelength loop of wire. That way, the 90-degree rotation of the circular polarised signal translates into a 90-degree phase shift between the horizontal and vertical elements.
Imagine trying to thread a corkscrew through the elements along the length of the boom, and you'll get it.
Gordon 2M0YEQ