Routing coax cable for HF radio

Submitted: Monday, Jan 21, 2008 at 23:24
ThreadID: 53769 Views:2901 Replies:9 FollowUps:5
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Hi all
I've just bought a second-hand Codan HF radio and wonder where best to run the coax cable for the antenna. Should it be separate from other wiring as much as possible,or will the shielding mean that it doesn't matter much?
Regards
John
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Reply By: Dennis in Scotland - Tuesday, Jan 22, 2008 at 00:23

Tuesday, Jan 22, 2008 at 00:23
Hi John,
Mounted mine into a Troopy, cable ran from bull bar back under the grill along the engine bay and through a grommet in the firewall. From there it went behind the 'kick panel' along the floor (under the plastic bit that holds the carpet/vinyl) and finally connected to the main unit behind the seat panel.
Point is, it was along side a lot of the vehicle's wiring and I never noticed any interference.
Just make sure your antenna and main unit have a good earth and you should be OK.
Gawd, just starting to snow here!
Cheers,
Dennis
AnswerID: 283037

Follow Up By: Member - Jiarna (NT) - Tuesday, Jan 22, 2008 at 01:12

Tuesday, Jan 22, 2008 at 01:12
Thanks Dennis
I'm hoping that will be OK as it is the easiest way to go.
We could use some of that snow if you have any to spare. Here it's been over 40 deg C just about every day so far in 2008.
Cheers
John
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Reply By: Member - Jon W (QLD) - Tuesday, Jan 22, 2008 at 07:34

Tuesday, Jan 22, 2008 at 07:34
John,
Just a hint. If you have trouble pushing the antenna cable through the grommet, push the plastic body of a bic biro through it first and then feed the cable into that. The biro body can then be removed by pulling it over the free end of the cable.
For what its worth.
Jon W
AnswerID: 283044

Follow Up By: Member - Jiarna (NT) - Tuesday, Jan 22, 2008 at 07:45

Tuesday, Jan 22, 2008 at 07:45
Hi Jon
Thanks for the tip.
Cheers
John
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Reply By: Member - Mike DID - Tuesday, Jan 22, 2008 at 07:59

Tuesday, Jan 22, 2008 at 07:59
You'll minimise chances of problem on the various frequencies you operate on, if you keep it as far away as possible from any other wiring.
AnswerID: 283050

Reply By: 96 GXL 80 series - Tuesday, Jan 22, 2008 at 08:22

Tuesday, Jan 22, 2008 at 08:22
Hi John,
I also have the same model only in 4.5lt.
I have HF and VHF / UHF installed.

I ran my cables (Antenna) along the passenger side through the rubber grommet with no problems.

Make sure you run a separate earth from the mounting point (Base) of antenna mount as the Alloy B/Bars are not a good earth or contact.

I ran a twin earth from that point and connected to the body and 1 to the chassis.

So no interference problems, but with a Diesel you might have to earth everything including the exhaust.

Cheers
AnswerID: 283057

Follow Up By: 96 GXL 80 series - Tuesday, Jan 22, 2008 at 08:32

Tuesday, Jan 22, 2008 at 08:32
John,
re the earthing, I have run the twin leads from the earthing point or base of mount.

As I have found if you piggy back them you seem to get more interference than running a separate lead for each contact,

EG: 1-1 1-2 1-3 1-4 and so on rather than 1-1-2-3-4-5-6 etc

Cheers
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Reply By: Peter 2 - Tuesday, Jan 22, 2008 at 08:27

Tuesday, Jan 22, 2008 at 08:27
Both Barrett and Codan advise that the wiring should be kept as seperate as possible from the rest of the HF wiring.
I used to install them, usually ran the power on one side and antenna connections the other.
The real biggie is to keep everything away from the control head cable as it seems to be the most prone to interference.
As has been said earths are the biggest cause of problems. Remove at least one bolt from the bullbar mounts to the chassis, clean surfaces back to bare metal and reinstall the bolt. Just because your driving lights work through the poor grounding of the bullbar to chassis doesn't mean the HF will.
Don't forget to connect the ground wire between the transmitter and the vehicle body and never connect the negative power lead to the negative battery terminal. The negative power lead should be connected to the body/chassis end of the the main battery negative.
The reason for this is that if the main negative/ground connection to the battery becomes very poor the starting current when you start the motor takes the path of least resistance through the HF! They never work again!! This applies to anything that has a decent size cable connected to the battery.
Peter
1996 Oka Motorhome

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AnswerID: 283058

Reply By: Grungle - Tuesday, Jan 22, 2008 at 08:32

Tuesday, Jan 22, 2008 at 08:32
Hi John,

Also having good quality coax makes a big difference as well. I have used RG214 which is double shielded and extremely low loss but is quite thick. Coax such as RG213, RG223 and Cellfoil are highly recommended. I have run mine from front left bullbar accross the front and then along the right side of the engine bay to the transceiver under the drivers seat. I have encased mine in harnessflex as well to stop any rubbing of the outer insulation.

I get no interference at all whilst driving but I have a mechanical diesel. The coax is bundled next to a whole host of other cables as well.

I prefere good qaulity Andrews or Huber & Suhner crimp connectors as well over soldered. I find soldered ones have too much flux residue left after soldering and it can be corosive in the right environment. Seal all external connections with self amalgamating tape as well to keep water out. Oh and earth, earth, earth.

Regards
David
AnswerID: 283060

Follow Up By: Member -Signman - Tuesday, Jan 22, 2008 at 15:25

Tuesday, Jan 22, 2008 at 15:25
Hi David
"transceiver under the seat" ?? Just avoid Nolans Brook when you do the Cape York trip- or for that matter any other unpredictable deep water crossings !!!
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FollowupID: 547713

Follow Up By: Grungle - Tuesday, Jan 22, 2008 at 21:01

Tuesday, Jan 22, 2008 at 21:01
Yes I know but unfortunately I do not have anywhere else to mount it until I get my cargo barrier.

BTW we crossed Nolans Brook June 07 when up at the Cape and had water over the bonnet. I thought positive thoughts though and didn't have problems. Yes the HF was fitted under the seat.

Lots of water around then as well as broken cars due to water crossings.

Regards
David
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Reply By: Vince NSW - Tuesday, Jan 22, 2008 at 09:59

Tuesday, Jan 22, 2008 at 09:59
Hi John,
I have all the cables running together( next to each other) The only one I had any problems with was the power cable for the fridge. Caused interferance when fridge cut in & out. Moved fridge power to the other side of cabe & problen went away.
Vince
AnswerID: 283083

Reply By: Louie the fly - Tuesday, Jan 22, 2008 at 10:59

Tuesday, Jan 22, 2008 at 10:59
It's best to keep the wiring as separate as possible. We had a Toyota Camry wagon some years ago with HF, VHF, UHF & 27 Meg fitted (tight squeeze). The coax's ran in a bundle into the cargo area from antennae mounted on front, except HF which was towbar mounted. They ran through the engine bay and somewhere, caused some interference to the BCM or something like that. One day, while making a turn, the wrong turn signal to come on. The driver was involved in an accident that ended with the wagon being a write off.

After investigation it was found that the coax's were interfering with the vehicle circuitry. Go figure. BTW, driver not hurt.
AnswerID: 283089

Reply By: Member - Jiarna (NT) - Tuesday, Jan 22, 2008 at 14:48

Tuesday, Jan 22, 2008 at 14:48
Thanks everyone for your replies. I'll run the power cables on the opposite side to the antenna cable, but other than that it should be OK. I have a mechanical diesel, so hopefully won't have too much interference to worry about. I have earthed the antenna base from the bullbar to the body, and the transmitter to the body, and cleaned up the earth connection from the battery to the body. With a bit of luck, it will all work OK :-)
John
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AnswerID: 283124

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