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Cophase antenna coax.

Slowpoke

Member
Jan 29, 2022
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Ok, need advice. I did look through feeds, but got dizzy, and experienced some vertigo reading a lot of the technical jargon. So, keep it as simple, explicit, and succinct as possible. I'm out of dramamine, lol!
Looking at updating my old original, probably low watt, high loss co phased coax. I do prefer cophased, as I do notice better, louder reception, maybe due to the extra "signal capture" or two antennas, compared to a single? Researching coax, I read the best coax for cophased antennas is RG59, as opposed to RG8, but also read LMR400 or 240 UF, is possibly superior for single antenna, but no mention of max wattage handling, or if good for cophase. I'm keeping my two Wilson 2ks, as they seem to work very well, but another question popped up, that I will ask in another thread.
So, advice? I am running max 450-500 watts, T680, mirror mounts...
Length of coax ? T connector or harness? I realize there's the 75 ohm, to 50 ohm (so, does that apply to harness, or just using a t connector?)
Thank you!
 

Crawdad

Down in the mud invasive species
Nov 11, 2016
902
1,881
153
You will need a 75ohm phasing harness (RG59 works fine) to connect your Wilsons in a phased array. That will present something close to a 50ohm impedance to your radio. Pre-made harnesses available, no "T" required, easy peasy. No 50ohm coax required.

73
 
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Slowpoke

Member
Jan 29, 2022
58
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You will need a 75ohm phasing harness (RG59 works fine) to connect your Wilsons in a phased array. That will present something close to a 50ohm impedance to your radio. Pre-made harnesses available, no "T" required, easy peasy. No 50ohm coax required.

73
Thank you sir!
 
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Slowmover

BANNED
Feb 17, 2015
5,280
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Where the West Begins.
Did a long T680 install thread addition last summer into fall (“t680” in title).

Truckstop WILSON with FME connectors is an easy choice. Bypassing OEM coax reduces AM/FM performance, but GREATLY improves CB.

— I use 7’ Skipshooters on aftermarket PRO COMM mounts that bolt OVER the original arm locations. (Antennas are just under 14’, an ideal height).

The two Amateur-oriented components added — West Mountain DSP Speaker and Morgan Systems 411cb Bandpass filter — greatly reduce noise and clarity in RX (TX also for BPF).

It’d be more work to snake an ARIES cophase harness (BELDEN cable + AMPHENOL ends), but possibly worth it.

A DC/RF ground point in the overhead can be drilled thru thE thick steel shelf from Underneath near a center visor post (easy to locate by feel). Same for going up thru curtain track indentation. (No one will see it). Shortens DC power from BATT by half.

No matter what coax or how it’s run the mirror arms need attention re RF Bond. It’s poor. The mirror mount points ON THE CAB need paint removed and woven braid run from stock or aftermarket mounts.

Ideally, also bond all door hinges and cab at lower four corners.

Exhaust system bonds is recommended, I haven’t tried it yet.

Mobile Install Bible

.
 

Slowpoke

Member
Jan 29, 2022
58
46
18
That's a lot to do. Maybe this spring.
Reading through coax posts, etc, the Wilson, and other typical truck stop cophase is mostly mini 8, which should not be used. Packaging does say 75 ohms, but how all that works, when the recommendation is RG59? Some cb shops, and manufacturers make lmr240 cophase, and swear by it. I went on Wilson website. They advertise their cophase clear coax as mini8 rg59u. How both? I called, and asked. They're checking "and will get back to me." Maybe a mis advertisement.
Anyway, I use Wilson for single, but would prefer rg59, with amphenol ends. I did use extra ground strap from door to body, now to do body to frame. Extra grounding can't hurt. My sleeper lights do flicker when transmitting on the 450w radio. Rf chokes may help. Not a big deal. The filter is a good idea also. I'll look them up. I read good things about skip shooters. 7'? Yikes! That should get the load up above the cab for sure, lol
I'll save the message, and come spring work on the rest. Thank you.
 
Last edited:

Slowpoke

Member
Jan 29, 2022
58
46
18
I'm just going by all recommendations I've read. Rg59 for cophase. Never use mini 8, etc, as they are 50 ohm, and cophase requires 75 ohm. Some say lmr240 is ok. Again, Wilson cophase, mini 8 says it's 75 ohm. I called the manufacturer and asked how that is, and why the website advertised cophase says mini8 rg59. They did not know why, but said a tech would get back to me. All recommendations from almost all sources I checked say rg59 ua with stranded center. I'm not a coax expert, so I defer to those who are, hopefully.
 

Crawdad

Down in the mud invasive species
Nov 11, 2016
902
1,881
153
I misread your post. Yes you are correct in not using RG-8x for your dual antenna set-up since it's 50ohm. Firestik sells a decent RG-59 phasing harness if you lack confidence in the Wilson @ the FlyingJ. I used the Firestik harness for a while, no issues. Later cut it up to use as an impedance matcher for a full wave loop antenna.
 
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Slowpoke

Member
Jan 29, 2022
58
46
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I misread your post. Yes you are correct in not using RG-8x for your dual antenna set-up since it's 50ohm. Firestik sells a decent RG-59 phasing harness if you lack confidence in the Wilson @ the FlyingJ. I used the Firestik harness for a while, no issues. Later cut it up to use as an impedance matcher for a full wave loop antenna.
Firestick does, OK. I'll check them out. I need to find a mirror mount attachment I've seen online. If not, I'll need fme connectors, so I can fish through mirror arm. If only truck manufacturers actually ran quality coax, to proper specs, etc! He'll, trucks are expensive enough, so why not?
 

Slowpoke

Member
Jan 29, 2022
58
46
18
Well, I called the manufacturer of Wilson/Road Pro, and talked to a tech. I told them about the advertising indicating their cophase coax was both mini8 and rg59. They told me it was a misprint, that they were unaware of, that they'd check into it. It looks exactly like their mini 8. Then I called a few well known cb shops that sell it, and asked them. They told me mini 8 and rg59 were the same. ???
It does say 75ohm, but mini 8 on packaging at retailers.
Well, with those varying answers, for purposes of cophasing, I'll stick with actual rg59, or TL LMR 240.
 

BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,217
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Phasing harness can be RG59...RG6...or RG11 ALL these are 75 OHM coax's...
They should be 1/4 wave long - each antenna X velocity factor (depends on type X .66 or (?) = total length
After that combination ANY convenient length of 50 OHM RG58/"Mini" 8x or RG8 type works just fine.



 
Last edited:

BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,217
4,817
373
35 miles East of Indianapolis

  • Model F-63
    Dual 4 foot Super Stiks include high quality 3-way aluminum mirror mounts and a full size 18 foot phasing harness. Skin packed on board.

Hustler Antennas have been produced in the U.S.A. for over 40 years. Since 1985 Hustler Antennas have been manufactured and marketed by New-Tronics Antenna Corporation in Mineral Wells, Texas
 

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