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Lower SWR with 102 than 108

Ok I put the 102 back on and with 5w power on 27.405 I'm at 1.3 and same on 26.965. getting out good. Hearing people miles away so I'm gonna stick a fork in it. Thanks for all the help. I was under the impression that I was needing 108 for proper resonance but on the meter it was worse than the 102. Again thanks for the help.
 
I am getting a lower SWR with SS 102" whip (aprox. 1.3:1) than 108" (1.6:1) on 27.205
I'm using HD stud mirrot mount on my semi. If I go down to 25.405 I get 1.2:1 with the SS 108" whip. Should I roll with the 108 or put the 102 back on?
Sorry in advance for the newb question.


Per the above, there is more to look at than just SWR.

A picture always helps, as a start. Close enough to see mount, far enough back to see relation to cab.

A “better” mount can help. A better stud, also. The DC ground. Etc. All worth some time.

What’s SWR at cruising speed? Some steel whips bend quite a lot.

An ASTATIC SWR Meter from one of the chain truckstops plus a three-foot jumper is a good-enough tool to have given the price.

You’ll always hear, “upgrade the coax”, and I’ve found improvement in every big truck. Same for “clean power”.

Call it TLC.

(Or in my case, getting carried away. The latest truck radio power cord assembly weighs 16-lbs).

I usually do one project at a time. You know . . about the time it’s finished they put you in a different brand of truck, right?

.
 
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I’m not sure how folks come up with 108”, to be honest.

9ft is approx 1/4 wave for 11m, near enough as a starting point. Because most people use a poor RF ground for mobile installs, thus requiring a longer radiating element, they found that when they used a 9ft whip they got a good SWR. Those with a good RF ground found they needed to trim several inches.

The standard formulas for working out the length of a dipole or quarter wave in feet (468/f or 234/f respectively) do not take into account the velocity factor of the material used. There is nothing wrong with doing that because if you start out assuming the VF is 1 then as any given conductor is 99.9% likely to have a VF below that then you're not going to end up with a length you have to add to which is harder than one you can simply trim down.
 
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If it tunes good use it. If you were getting a better swr with an 84 inch whip then I would investigate further. :LOL:

I'm just surprised my friend w9 hasn't chimed in on this 1.3 Swr ? Chris going once .. going twice ...:whistle::) Wait I'll answer for him " It's fine Leave it Alone " !:LOL:

I think he only gets bent out of shape when someone uses more power than him. There's no amp involved here. :p
 
I am getting a lower SWR with SS 102" whip

Ahh, anyway. Never needed a 108” whip for a cb radio. Always been closer to 102 for me.

I agree with Captain Chaos and dledinger.

Back in the day, I once used a spring. I thought it was cool and being longer, like everybody was saying in radio land at the time, "...your whip needs to be 108" inches long for CB, the 102" inch whip was made for ham operators on 10 meters."
 
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