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Coax length.. does it matter or not

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Old 03-28-2012, 07:06 PM
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Default Coax length.. does it matter or not


I run a magnum s45hp radio ( turned down to 2Wdk and 35Wpep) with 6' rg8x to the dx500v,gives me (80Wdk and 400Wpep)and 12' of rg8x to the antenna, roadtech open coil, mounted on pass side about 8'' from cab and the bottom of the coil is about 3' below the cab.
EVERYTHING is grounded to the frame, as short as it can be.
The swr are at 2.1-2.7 with amp on, but just with radio @2Wdk the meter will not adjust over far enough to test swr.
The radio at 15Wdk and 80Wpep the swr's are about 1.3

WHAT GIVES?

Last edited by dxing440; 03-28-2012 at 08:03 PM.


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Old 03-28-2012, 07:36 PM
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Coax information

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Old 03-28-2012, 07:37 PM
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Quote:
mounted on pass side about 8' from cab and the bottom of the coil is about 3' below the cab.
It is " inches, not ' feet


As long as you continue to run that antenna 8 inches away from the cab of your pick-up truck, i think you are going to have a problem.
You need get that antenna away from or above the cab or it is just gonna drive you crazy.
The Coil of that antenna is below the level of the roof it is even worse.

This is the worst place to mount a loaded antenna , even more so with the LOAD ( the COIL) mounted below the roof


I really recommend the Wilson 5000 Mag mount, and stick it up on top of the cab.
You are gonna pay 85 or 90 bucks for a Predator and if you stick it in the same place i bet you will have the same problem.


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Jeff
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Old 03-28-2012, 07:41 PM
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And if you keep smakin' that amp with 80 watts input - it will fry too. The Texas Star amp repair guy is a member of this forum - BTW. He said the most common reason for failure with their amps are people trying to get more watts out of the amp by putting too many watts in. Of course; ya don't have to take my word for it . . .
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Old 03-28-2012, 07:49 PM
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Move the Antenna away from or above the cab

Look at this Picture, if you have to mount the antenna behind the cab It SHOULD look like this:





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Old 03-28-2012, 07:56 PM
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Hey bootymonster, good info on the coax. Although, I just cant understand how to calculate the half wave, full wave, thing for 11 meters or any meter. LOL

And audio, ive heard the antenna suggestion more than once, wilson 5k must be a good one. I just dislike magmount antennas, but its that, or keep a huge bottle of asprin, for the coil antenna.


Thx

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Old 03-28-2012, 08:00 PM
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hey robb if you read my 1 post again, its at 2wdk and 35pep NOT 80

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Old 03-28-2012, 08:10 PM
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Quote:
Originally Posted by dxing440 View Post
hey robb if you read my 1 post again, its at 2wdk and 35pep NOT 80
Quote:
. . . The radio at 15Wdk and 80Wpep the swr's are about 1.3 . . .
???
Just sayin' man . . .

First off, just run as much coax as you need to make it from point "A" to point "B". With just a couple extra feet of wiggle room for good measure. Forget about all of that BS about how long a piece of coax needs to be. Get yourself a Predator antenna, use a puck mount and cut the sheet metal in the center of the roof of the cab, run some LMR-240UltraFlex/RG-58 coax, and be done with your SWR problem. Or a mag mount Wilson 5000 too . . .

BTW - if you run more than the Texas Star recommended power into that amp (20 watts/25 max), you will defeat the AB class amplification you bought that amp for.
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