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TECHNICAL REVIEW:  
          INSURING ANTENNA LONGEVITY
 
 

> Special Web Report:  2005-02-04  
   by Ray Davis, KD6FHN  


Here are some of the things everyone, who puts "ANY" antenna, of "ANY MAKE", or "ANY MODEL" of a motorcycle should consider: 

  1. Before you even put the antenna on your motorcycle for the first time, take all the little set screws out along the entire length of the antenna, and put them back in with LOCKTITE on them.  Save the little allen wrench, you'll need it in the future.  I keep one on the motorcycle at all times. 

  2. Do "NOT" use the type of LOCKTITE that freezes the screws in permanently.  Don't use Kraze glue, or anything like it, or, when you do need to get the screws back out to do some repairs, you will strip out the screw heads.  LOCKTITE is available in different grades, and will hold the screw from backing out under severe conditions (on a motorcycle,) without using the type that is permanent.  A few minutes here, will save you some embarrassing moments, frustration, and money later.  If the Comet repair guy, Jim, can not get the screws out, he does have a compound that helps get the screws out, if that doesn't work, he can not repair them and therefore must charge you for a new one.  At home I sometimes have to drill out the screws with a left hand twisted drill for our members, but sometimes that does work either, if they have used something that locks in the screws permanently.  

For a few years we were fiber glassing all the Comet Z780 (replaced by the Comet SBB-7) antennas at the middle phasing coil, and later on even at the base.  But since then, we have discovered that by tying a piece of 20 lb. test monofilament fishing line just above the center phasing coil, and running it down to the front of the trunk rack on a GW 1500/1800, we no longer have to do all that fiber glass work.  The monofilament line takes all the rearward pressure off the antennas at Highway speeds. We mostly run with the SBB-7 when we are doing charity events, and/or we are not going to be where we can hit the repeaters easily, or when we want to talk bike to bike over long distances on simplex. However, I have run the Comet SBB-7 to San Antonio TX and back several times for the WOTI (Wings On The Internet) BBQ and on the SCMA 3 Flags Classic Mexico to Canada several years in a row, using the monofilament lines, with no ill effects to the antennas. Most of the time around here everyone runs the Comet HP-32, because it is indestructible under any conditions, and you don't have to take it off when entering, or leaving your garage with it mounted on your trunk rack.

A few years ago in an earlier MARC Newsletter report, four of the most common Comet antennas that we use on the motorcycles was tested for the entire summer (42,000) miles. None of those tested broke or discontinued to work. Almost every spring Comet gets new prototypes of antennas for testing before they put in an order for them. The owner of NCG (Comet) gives the prototype antennas to me and I test them all summer on the back of the trunk rack of the 1800 Gold Wing that I now ride. I do run them stock for the summer or until I break one, and then we experiment with what it takes to make them survive on a motorcycle. Sometimes it is as simple as tieing a 1 or 2 inch piece of ribbon at the very tip of the antenna, sometimes it is tieing the monofilament fish lines to the taller antennas. On the really tall (7 foot Maldol PR-212D) we have to use 3-20 Lb. test monofilament fish lines tied to it so it can be used on the back of the motorcycle. One line at the top of each coil.

Because of the stress on the trunk lids caused by the antennas mounted on the rear of the trunk rack, we found that the rear legs on the rack were cracking the trunk lids on the trunks. To put a stop to this we designed a 2.5 X 3.5 inch X .060 inch thick stainless steel plate to spread the weight around over a much larger area. We have not heard of one single trunk lid being cracked after the installations of the stainless steel plates.  

You see this is a lot work. None of these antennas by "ANY" manufacturer is, or was ever designed to be used on a motorcycle. They are designed to be used on a vehicle that has at least 4 wheels with 4 cushy radial tires on it, not a 2 wheel vehicle with two very hard bias ply tires with rock hard side walls and 40 lbs. of air in them.  
   

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