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Old 28-04-2020, 20:26   #1
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Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8 ft p

I know very little about VHF and antennas, is length critical? I am working on replacing the headliner inside my pilothouse and the wires and cable that run to the radio are just a mess. I would like to tidy them up and to do so I need the antenna cable that goes to the Masthead antenna to be a little longer. There is a six-foot piece of cable that goes from the back of the radio down behind the cabinetry near the electric panel. There it connects to the cable that comes out of the base of the mast. Can I just replace that 6 foot RG-58U cable with an 8-foot one so I have a little extra length to create a tidy run of wiring to the radio? Where would I buy that cable? The 6-foot cable has a male connector on one end and a female connector on the other. If I could get an 8 ft version of the same thing I would be smiling. Let me know what I need to know. Thanks everybody
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Old 28-04-2020, 21:00   #2
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

You need to order two items. This is the cable: https://www.amazon.com/Marine-Antenn...8132582&sr=8-8

and this is the coupler that “makes one end female”: https://www.amazon.com/Maxmoral-2-Pa...8132652&sr=8-4

You get 2 couplers for that price. I think you have a coupler in the old cable, but recommend to replace it. Make sure the connectors index correctly in the coupler (the pointy bits go in the cutouts) and tighten them hard.
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Old 28-04-2020, 23:03   #3
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

^^^^^

And Nick didn't say it, but it is quite alright to add a few feet (or more) of coax to tidy up the wiring. There is a small signal loss in each additional length, but a few feet will make no difference at all to your perceived performance.

And also, after hooking the new cable up, with tight connectors, give it a test run to be sure that the new cable has no faults, and then wrap the connectors with some form of waterproofing. Amalgamating tape is good, a butyl rubber sealant like is used for bedding deck hardware is good (there is a specialist one called "coax guard" or sumpin like that) or even plain PVC electricians tape... anything to keep water out will help.

And that should see you through the job.

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Old 29-04-2020, 05:48   #4
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

Thanks Nick for the links, and Jim for the additional support. Pieces ordered!
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Old 29-04-2020, 15:31   #5
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

Quote:
Originally Posted by AZ-Oldguy View Post
I know very little about VHF and antennas, is length critical? I am working on replacing the headliner inside my pilothouse and the wires and cable that run to the radio are just a mess. I would like to tidy them up and to do so I need the antenna cable that goes to the Masthead antenna to be a little longer. There is a six-foot piece of cable that goes from the back of the radio down behind the cabinetry near the electric panel. There it connects to the cable that comes out of the base of the mast. Can I just replace that 6 foot RG-58U cable with an 8-foot one so I have a little extra length to create a tidy run of wiring to the radio? Where would I buy that cable? The 6-foot cable has a male connector on one end and a female connector on the other. If I could get an 8 ft version of the same thing I would be smiling. Let me know what I need to know. Thanks everybody
Replace with 8x, same connectors.
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Old 29-04-2020, 20:23   #6
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

And, I believe the 8x is a multi strand (more flexible) and slightly lower loss. The lower loss part really isn’t a big deal but the more flexible attribute can be important if there is a lot of movement at the connector etc.
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Old 30-04-2020, 07:06   #7
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

The link I posted is for RG-8x
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Old 30-04-2020, 07:28   #8
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

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The link I posted is for RG-8x
Good work sending the links, Jedi.

The length of the coax to antenna is not critical and several feet can be added or subtracted with no problems.

Higher quality coax, like RG-8x will usually be a great improvement. For now, just replace the radio-to-mast section.

Next time you have the mast down, consider replacing the coax inside the mast with RU-8x.
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Old 30-04-2020, 09:54   #9
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

Next time the mast is down consider running the coax full length from antenna to radio with no junctions.
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Old 30-04-2020, 10:01   #10
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

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Originally Posted by Adelie View Post
Next time the mast is down consider running the coax full length from antenna to radio with no junctions.
Excellent suggestion.

Several extra feet of coax will add minimal losses. Each connector adds substantial losses.
A one piece coax from masthead antenna to back of radio is best - and you get rid of the concerns about moisture intrusion/corrosion at intermediate connectors
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Old 30-04-2020, 10:26   #11
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

Quote:
Originally Posted by Adelie View Post
Next time the mast is down consider running the coax full length from antenna to radio with no junctions.
That was my thought too, in fact since it removes two connections, might be worth doing it now.

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Old 30-04-2020, 11:05   #12
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

RU-8X? Is that the Russian version for RG-8X? [snicker snicker]
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Old 30-04-2020, 13:59   #13
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

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Each connector adds substantial losses.
Please add citations for this statement. There have been several posts here on CF in the past citing the opposite opinion, including one with something like thirty connectors of varying types in series with no measurable loss. One fairly pessimistic figure that is generally accepted is 0.1 db per connector, but even that figure is hard to support. Several sources suggest more like 0.01 db in the HF realm. Either of these figures means that the loss is completely insignificant.

The loss from a barrel connector and two PL-239 males is infinitesimal, but the chances for damaging a cable whilst unstepping/restepping a mast are significant... to say nothing of the inconvenience involved.

Protecting against moisture is important, as I posted upthread.

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Old 30-04-2020, 23:34   #14
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

Jim, you are correct that a good connector correctly installed has very little insertion loss.

IME, the insertion loss is inversely proportional to the connector price and also inversely proportional operator experience.

You can be darn sure a Huber+Suhner or a Pasternak connector installed by an experienced operator with the correct tooling will have no noticeable insertion loss.

Yet a no name PL-259 el cheapo connector badly soldered by a drunken sailor early in the morning has somewhat more loss (waaaay more). Whack two together with a dirty misshapen adaptor and you can kiss goodbye to using the radio.

But of course, you know this!
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Old 01-05-2020, 00:16   #15
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Re: Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8

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Jim, you are correct that a good connector correctly installed has very little insertion loss.

IME, the insertion loss is inversely proportional to the connector price and also inversely proportional operator experience.

You can be darn sure a Huber+Suhner or a Pasternak connector installed by an experienced operator with the correct tooling will have no noticeable insertion loss.

Yet a no name PL-259 el cheapo connector badly soldered by a drunken sailor early in the morning has somewhat more loss (waaaay more). Whack two together with a dirty misshapen adaptor and you can kiss goodbye to using the radio.

But of course, you know this!
Yeah, but when considering that said drunken sailor is using second hand TV coax , salvaged from a defunct rooftop yagi, what difference does it make?

And for t hat matter, the OP was postulating buying ready made cables which are usually only manufactured after smoko so the hangovers are abated and quality control is in full swing.

No worries, mate!

Jim
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