| 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!. |