so i have been studying some pictures of comp suburbans to see if there is something i missed as far as setup. no difference from mine from what i can see except for one thing. i noticed all the coax runs are kept separate from each other, no one coax line is running parallel with another coax line. is this important to do? i have my jumpers running parallel and zip tied to each other and the main antenna line. is that bad?
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parallel coax lines, bad idea?
- Thread starter groundwire
- Start date
I’ll take a crack at it.
The coax is a circuit.
A problem I have in the big truck is that I have several jumpered devices after the radio (towards antenna).
The coax comes in VERY near the radio rear, but then makes a loop of several feet to come back near the same point to attach to the radio.
I can get a flat match with Radio power at 2W or at 12W. But once the KL203 is on, I have to use the MFJ-945e Tuner to keep the SWR below 1.6-SWR (up to 90W Forward with 3.5W Reflected at 1.4-SWR; I back it down from there).
Sound familiar?
I’m limited as to mounting options (no holes drilled). But other guys in the same boat have been able to do workarounds, one of which I’ve brought the gear with me to trial fit. (Moving gear outside overhead console).
My example may not be analogous. But were I you I’d take ALL the gear from it’s present location and spread it out to avoid “coax parallel” to see if that changed the effects currently seen.
On this truck there’s only so much I can do with antenna mounts. That’s the center culprit.
I’d think comp rigs would run equal lengths to each antenna on different sides of the vehicle. Same mirrored run.
And check for vehicle electric interference. (A guess).
Anything crosses it ought to be at 45-90/degrees. Etc.
.
The coax is a circuit.
A problem I have in the big truck is that I have several jumpered devices after the radio (towards antenna).
The coax comes in VERY near the radio rear, but then makes a loop of several feet to come back near the same point to attach to the radio.
I can get a flat match with Radio power at 2W or at 12W. But once the KL203 is on, I have to use the MFJ-945e Tuner to keep the SWR below 1.6-SWR (up to 90W Forward with 3.5W Reflected at 1.4-SWR; I back it down from there).
Sound familiar?
I’m limited as to mounting options (no holes drilled). But other guys in the same boat have been able to do workarounds, one of which I’ve brought the gear with me to trial fit. (Moving gear outside overhead console).
My example may not be analogous. But were I you I’d take ALL the gear from it’s present location and spread it out to avoid “coax parallel” to see if that changed the effects currently seen.
On this truck there’s only so much I can do with antenna mounts. That’s the center culprit.
I’d think comp rigs would run equal lengths to each antenna on different sides of the vehicle. Same mirrored run.
And check for vehicle electric interference. (A guess).
Anything crosses it ought to be at 45-90/degrees. Etc.
.
I would certainly think that EMF can be generated on the braid when a current is passing through the center conductor. The braid would be inductively coupled and therefore could couple to another braid alongside. How much effect this would have at RF frequencies with the braids all at the same DC potential, I don't know. I would keep it all separated if possible, just because.
If on cellular towers cable can go parallel I don't see a reason not to do it on ham bands.
Mike
Mike
No reason whatsoever that cables cannot be run in parallel or in tight groups. That being said if you have BAD common mode issues then RF can spill over from one cable to the next via capacitive coupling but if that is the case you need to solve the right problem first.
All my coax runs in a bundle up to the roof bar one to the MFJ 998 tuner in the kitchen feeding the 77 feet vertical.
The coax for the OCF, Imax 2000, Diamond X510N 2/70 antenna, and coax for the scanner antenna all are bundled till the roof and from there go to the antenna's.
Never had a problem and some antenna's which are resonant still have an SWR of 1:2 on the edges of the band.
All antenna's are grounded on the roof and below at the coax switch and radio and tuner and P.A. directly to a grounding system 8 feet away and connected to the radial field of 3000 feet in/on the ground.
Running 1 KW here without problems in a build up area, no people with pitchforks for the door then, no negative effects on the other antenna's or (t) ransceivers.
The coax for the OCF, Imax 2000, Diamond X510N 2/70 antenna, and coax for the scanner antenna all are bundled till the roof and from there go to the antenna's.
Never had a problem and some antenna's which are resonant still have an SWR of 1:2 on the edges of the band.
All antenna's are grounded on the roof and below at the coax switch and radio and tuner and P.A. directly to a grounding system 8 feet away and connected to the radial field of 3000 feet in/on the ground.
Running 1 KW here without problems in a build up area, no people with pitchforks for the door then, no negative effects on the other antenna's or (t) ransceivers.
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