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MARC Technical Center Comet Antenna Report
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TECHNICAL REVIEW:  
          COMET Antenna - CSB790A
 
 
First report written 5-21-08;

This past Sunday May 18th 2008, seven of our MARC motorcycle ham radio mobiles were working the ADA Conejo/Ventura Tour de Cure charity event and were using the (new to us) Comet CSB790A antennas. These antennas are 61 inches tall and weight 16.5oz and have 5.1dBi gain on the 146MHz band and 7.7dBi gain on the 446 band.

The other antennas that we had been using before that are about 7 inches shorter and have 4.5dBi & 7.2dBi respectively and thought the shorter antennas were doing a good job for us too. Apparently the difference of .6dBi gain on the 146 band and the .5dBi gain the 446 band is huge in terms of dBi gain. Because the very first time I put this Comet CSB790A antenna on the antenna mount on the rear of our white 04 Gold Wing (Casper) to give it a test right there at the Comet warehouse in Chino CA I was totally surprised at what happened. I was able to talk to my wife Bonnie on 2 meter simplex 35 miles away in Irvine, CA. There are 2 rolls of mountains between Chino & Irvine, one roll of mountains is 4 to 5,000 feet tall and the other roll of mountains a little less. Now I don't know how that was possible, but it was very impressive. Bonnie was using a Kenwood TM742A on the 146 band (2meters) and 5 watts of power going to a Comet GP-9, up about 35 feet at the house and I was using this Comet CSB790A antenna and 10 watts of power from a Kenwood TM742A mounted on the motorcycle.

The fact that these antennas performed so well during that first test prompted 8 other MARC members to immediately purchase these Comet CSB790A antennas for the Conejo/Ventura ADA charity event. It really paid off in terms of better communications. In the 2 previous years, at this event, our communications were marginal to say the least. Using the same set up with tower height and radios used for net control in previous years, we (the ham radio motorcycle mobiles) were able to access the same Oat Mnt. BARN repeater on the entire route. In some areas on the longer routes, in the valleys where we were hidden from the repeater) we did have to open the squelch a little to just hear the repeater, but on high (35 watts) power and the squelch open we were able to make contact on the entire route.

Using the MARC simplex (144.370) frequency also had a big benefit using this Comet CSB790A antenna. When we were not down in a valley hidden from the repeater we were able to contact the MARC net controllers using MARC simplex on 2 meters. This also was a great benefit as we had 2 separate Kenwood TM742A's set up at net control, one for 144.370 simplex and the other for the Oat Mnt. BARN 446 Repeater.

We (MARC) are always looking for ways to improve our communications and make our work with these many charity events better and easier. The Comet CSB790A surely did that this year. I am sure we will be using this antenna for a long time on all of our charity events, at least until something better comes along.

I will be giving this antenna some more testing as we (3 MARC members on GW's) will be going North of the San Francisco Bay area over the 2008 Memorial Day weekend (putting on about 2000 miles) and I will be running the Comet CSB790A to test it at highway speeds for hour after hour for 4 days. 

Updated 6-4-08;

I am sure by now everyone has gotten their June 08 MARC Newsletter and have read about the 4 day ride doing the Southern CA M/c Assoc. (SCMA) California's US National Parks Adventure Ride and the disastrous fog we had coming out of the Sequoia National Park on the way home and the 2 accidents. The Comet CSB790A antenna survived that trip very nicely through 4 days of rain, mist & fog. The actual miles for the 4 days was 1992 miles and it was a rough weekend, from sea level to over 7,000 ft. over some very rough roads and also some very high highway speeds, but the SCB790A held up like a champ through it all.

TTYL, God Bless
73 Ray KD6FHN
Irvine, CA.

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