some quick help please

Use what ever length of coax you want. Simple as that. Francis antennas can be tuned, It just takes a hack saw. But if you are slip seating, I don't recomend cutting them because it might screw them up on the next ride. You best option is to go with what the package says which is 18 foot.

I don't run the cut to tune fiberglass antennas and I don't run Francis antennas. I run whip style antennas. I only run one now since I got sick of having to deal with two antennas all the time. When you run in the winters up north in alot of sluch,salt etc. You have to maintain the antennas and all connections.

My reception is not any worse running a single. My transmittion pattern is not any worse running a single either. I have a nice pattern and can get out all over. Bare foot usually gives me 10-15 miles pretty easy using a single wilson 5000 on the mirror. When I flip on the box, people hear me ALOT further. I have had calls from friends that were more then 35 miles away and they asked me were I was because they could hear me loud and clear on the radio. LOL

Ignore that channel jumper. That is the best option and the only option till the mods/admin decide to get rid of him.

If we don't respond to him then maybe he will just go away.

 

Physics and 4nec2 models I built to answer this question reveled this truth to me.

I used dBi exclusively. so the conversion factor of 2.15dBi=0 dBd isn't really relevent is it?
I was very careful to specify dBi on all my refrences except this one.

which like a pronoun refers to the last antenna mentioned, the dipole in free space (although I didn't label it as dBd because when I wrote it I was actually referring to a single antenna of the same design as the pair.

One what?

We are talking about a phased array of verticals vs a single vertical.

Then you admit there is increased directivity even for improperly spaced
antennas?

???? I'll show you my patterns if you like, sure looks like an improvement to me.

No it will give an increase in directivity of about 0.85 db. At least in a perfect world you know spherical chickens in a vacuum.

My model used full length dipoles.So short vs. long is irrelevant to the subject at hand.

Just think about this if the signal arrives from the front or rear then the signals are in phase and add together. If the signal arrives from the side it strikes one antenna before the other causing a mismatch in the phase when the signals arrive at the combiner. at separations of less than 1/4 wavelength the addition happens at the wrong time so the weaker signal level drags the other signal down at separations between 1/4 and 1/2 wave length the addition is really subtraction because the phase causes one of the signals to be negative. At separations of exactly 1/2 wave length all the signal is attenuated as in -1 +1=0

And while I have your attention and for the record monkeymade antennas are not significantly circularly polarized, almost no horizontal component.

Coax electrical length is determined by both physical length and velocity factor

I can't leave wrong statements to prevail by ignoring them. Sorry (I'm not sorry)

 

i'd go with the tallest antennas you can and still be around 13'6 at top. i've always noticed a difference by switching out taller Frances.