Shaft Lenght for 10K

[undertaker]

What size shaft do i need to run my 10k on top of my pickup??

 

[mackmobile43]

What size shaft do i need to run my 10k on top of my pickup??

12'' to 17'', anything longer and you just trade flexibility for stiffness other than that there's no significant purpose for shaft length when roof mounting.

But I'd say 12'' should be the minimum due to the nature of the coil and that it has a lot of rf energy radiated at that point which needs to see a couterpoise and putting it any closer to the roofline would make any counterpoise ineffective.

I've run a 12'' in on the roof of my car for several years and have great swr and good tx with just a magmount.

 

[DXman]

What length??

I have one on the top of my F150, it is a 22". I tired the 17", but it didn't tune good, so Kale recommended that I tire the 22" and it worked.

 

[jessejamesdallas]

What length??

I have one on the top of my F150, it is a 22". I tired the 17", but it didn't tune good, so Kale recommended that I tire the 22" and it worked.

Yep...Usually the 17" shaft is the shortest you would want to go with on the roof's. And if it won't tune very low in one place, most of the time all you need to do, is just move the antenna either forward or farther back, and it will tune better...But, if that's not a option, and you have a certain place already picked out where you want the antenna mounted, then your only other option maybe just to go with the taller shaft...Just keep in mind, the taller the shaft, the better chance your going to have of hitting something hanging low, that could snap-off the antenna!

Now, that is for the Regular Single Coil 10K's, and the Dual Coil 10K...

If you get the Single Coil Predator 10K Comp...Allot of guy's (including myself) have had good luck using the 12" shafts on the roof...Because of the coil design on those, they can be tuned (in most cases) around 1.1 to 1.2 SWR on the roof...But only on the 40 CB Band channels...If you have a "Export" radio, and plan on talking on the other Bands, then you wouldn't want the "Comp" 10K, since it's a more Narrow-banded antenna...

 

[555]

drill a hole install a FaTBoY Puck and run with either the 17 or 22 inch Comp coil

drill and mount on top of cab just about 6 inches in front of 3rd brake light
if you start to move toward the center of cab then reflect comes into play
or SWR

 

[15minigrass]

I run a 9" shaft w/pot belly spring then cut about several inches off the whip brought the SWR down close to 1.5:1. I guess the spring made up for the difference... peacem Jim....

 

[storm chaser]

I like to believe this.

The lower the coil is the more rf is pulled down. The higher the coil the more rf goes up. But I have nothing to stand on to prove this. But it would only make sense that rf is atracted to metal of the mobile. I like the short shaft low coils and believe that is why the wilson works so good for a small antenna. I wish they would make a longer bigger coil to hang with the big boy antennas. But I dont think the shaft size matters other than keeping your antenna straight at all times. I like the long shaft on the trunk with the coil even with the cab to radiate off the top. Just my opinion