[Antennas] Iron horse mobile antennas update

[Art Clemons]

> Well I got the 706 in the van and a trailer hitch and mount installed. 
>My buddy N4TOF and I put the 40 meter whip on and cannot get the swr down 
>for anything. The hitch and mount are all grounded well. The mount is a 
>good 8 inches away from the van. The antenna on 40 seems to only resonate 
>with the whip way down in the coil which you can't have and it resonated 
>only very high out of the 40 meter band. We can't get it to resonate 
>anywhere with the whip in the recommended position. We did try trimming 
>about 2 inches in all but don't seem to be getting anywhere. Is the antenna 
>too long? I know if it resonates high it's supposed to be short but pulling 
>it up in the shaft only results in a 3 to 1 in a very small bandwidth. 


I don't know what kind of antenna you're using, but your whip could 
either be too long or too short.  You also could find what ever coil 
you're using is being detuned by the body of your vehicle despite being 
eight inches away.  The normal safest practice is to have the coil above 
the roof of the vehicle if possible.  Incidentally, an easy way to tell 
if the whip is too long or too short is to measure exactly where the 
antenna is resonant, with the whip in its "normal" position.  If it's 
let's say 8 megs with a supposedly 40 meter antenna, then the whip is 
too short, similarly if it's 6 megs, the whip is too long.  One of the 
analyzers from MFJ, AEA, Autek et al are great for determining things 
like this quickly with no risk to your finals.