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Sent: Tuesday, March 28, 2006 15:14
Subject: Page #5 FAQ
Understanding the SWR readings on a Dual Band Antenna, Updated 3-28-2006

Hello Ray,
I was searching around the Web for info about the Comet CA-2x4SR
and found the www.marc-hq.org Website and your tech notes. It seems
to be that you have a lot of experience with Comet antennas. I
wonder if you could help me with my new CA-2x4SRB antenna, just
received from AES.

I tried to check the antenna for continuity: from the tip of the
antenna to the end of the cable center plug, and from the base of
the antenna mount to the outside portion of the cable end. I got
some weird results: no continuity from the tip of the antenna to
the center plug and continuity from the connector (shell) to the
lower first section of the antenna. The SWR on UHF seems to be low
(1.5:1 or less) but high on VHF (more than 2.7-3.0:1). Is this the
correct way to check this antenna?. How can I tune it on VHF for
lower SWR?.
Thanks in advance for your time and valuable help.
From: "Ray Davis" <raykd6fhn@earthlink.net>
Subject: SWR Readings Explained For Dual Band Antennas
Date: Thu, 02 Feb 2006 15:52:12 -0800
Juan, yes I work the HamVention with Comet in Dayton OH and also
test some of their antennas on the motorcycle to see if they can
survive there. The Comet CA2x4SR is one of our favorite and one of
the best selling and for sure one of the most durable antennas we
use on our motorcycles, so you have chosen an antenna that is top
of the line.
Because the antenna is a dual band there is capacitors in them that
interrupt the continuity so your meter will not show that. From
years of testing we know that the final and most reliable test is
the SWR, if that is good on both bands then you don't have a
problem of course. In your case, if the SWR is high on VHF then you
need to check your coax or any other equipment you have, like a
Duplexer that is in the line. If the antenna is new then it is
unlikely that anything is wrong with it, "BUT", it isn't totally
out of the question either, if it is the antenna then you need to
let Mick know so he can look at that batch of antennas and find out
if it is just one antenna or the problem is more serious. Thanks
for the email, it is always good to hear from the Comet customers.
Ray, Thank you so very much for your answer and for your help. Wow!..., it is good to know that someone, somewhere can help you. Thanks again!.

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