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Old 15-11-2014, 21:19   #1
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New VHF antenna cable, one piece or two/

Next step in the refit is the mast. New wiring and of course new antenna cable. The mast is keel stepped and there is a +/- 20' run from the step to the nav station.

To run the wire is not very straightforward so would very convenient if I have to pull the mast in the future cut the coax at the step and install connectors so I can just disconnect.

The question is, how much signal would I lose adding connectors vs a one piece cable from masthead to radio? If significant then I can leave it uncut and deal with the run to the nav station if the need arises.
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Old 16-11-2014, 03:18   #2
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Re: New VHF antenna cable, one piece or two/

Ret'd after 30yrs in Mar. Electronics. There is a small loss,but,in my experience,it is negligable in practice.
Use RG 8X or RG8U marine coax.Do not use RG58 for runs longer than 30'.
Use good quality PL 259 conns & PL258 union.Solder the center conductors.
Soldering the braid is a bitch,without melting & ruining the coax impedance.
I found it best to roll the braid back over the outer sheath,& screw the PL259 on over the lot.In case of RG8X,you must use a UG175 bushing.Trim some of the braid strands,roll braid back over outer sheath & twist/slide the bushing on over the lot.Then,screw the PL259 on & solder ctr cond.
I'm sure some purists are choking over not soldering the braid.I'm just repeating what worked for me for many yrs,with no problems.
Leave a drip loop below the antenna fitting & wrap rubber self sealing tape over the complete socket/PL259 connection @ base of antenna.Then coat it with "liquid electrical tape". I suggest using Shakespeare 5215 ant.-tough,flexible,decent performance at masthead heights.Should last for years. Cheers.
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Old 16-11-2014, 03:33   #3
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Re: New VHF antenna cable, one piece or two/

Certainly put in a connector in the cabin after the coax exits the mast. If nothing else, this becomes a good disconnect point if you are ever troubleshooting the radio or antenna system.

If you can get them, use "N type" connectors rather than PL 259 / 258. If you have the tooling, use crimp connectors otherwise use solder ones. These really only solder the centre conductor while the braid is secured with a screw clamp arrangement.

In fact, use any coax connector (say BNC or TNC) in preference to PL 259 / 258.
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Old 16-11-2014, 04:30   #4
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Re: New VHF antenna cable, one piece or two/

Geez, antenna and coax threads on a radio forum are like anchor threads on a boat forum or oil threads on a car forum!

So I might as well wade in here with my 2 worth as well!

So here is how I'd do this installation-

As mentioned, use RG8 or suitable coax for the mast run. If you plan on keeping this boat for at least 5 years it is worth your while to see if you can find coax with a "tinned" conductor and also braid. It makes it easier to solder but the main reason is corrosion resistance. Then you can have a connector somewhere at the base of the mast and use a separate run to the radio. This can be RG8x if you need the smaller cable but it can be most anything suitable for VHF frequencies. Again, try to get something with a tinned conductor and braid. And it is perfectly fine to have the mast coax come out the bottom for 5-20 feet if you want it to and it makes it any easier to hook up.

This company can make up lengths of cable for you if you have measurements:
Coax Cable assemblies|RF 50 OHM|RFID Cables|Custom coax assemblies

I've used them off and on for 17 years and have always been happy with them for delivering a quality product.

Far as connectors go, there are a bunch that work but most all service shops will have PL259 connectors on service equipment, and many but not all will have BNC/TNC adapters so while they pretty much all work the same I'd pick PL259's for everything as a tiny bit of insurance that if I ever needed service from somewhere at anchorage they'd most likely be able to have parts on hand.

As mentioned, best way to waterproof connectors is to wrap with electrical tape (3M 33 super is my personal choice of tape for this) then cover with "liquid electrical tape" or 3M Skotchkote and you'll be set hopefully permanently.

If you think you might be removing the mast in the future, a trick is to wrap the first layer of electrical tape "sticky side up", then cover with several regular wraps of sticky side down. This way you can peel the tape off easier and it is just as waterproof.
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Old 16-11-2014, 05:41   #5
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Re: New VHF antenna cable, one piece or two/

If you must use a connector, use an "N" type.

The problem is not so much the attenuation, as the potential for failure. "N" type much better in both regards.

But it should be possible to run the cable in one piece without a connector. I did last year, although my mast step is an 8 meter or so run from the nav table. You just cut the cable to the right length and tape the coil to the base of the mast when you crane in the mast -- simples. Then uncoil it and run it to your nav table. I really don't think that there is any compelling reason to have a connector there, and to my mind, a connector down at the mast base, in the dark and wet and out of sight, is just trouble waiting to happen.

FWIW, I used RG213/U cable. Not usable in every mast because it is quite fat, and not too easy to pull, but it's tough stuff with solid core and good attenuation properties at VHF frequencies.
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Old 16-11-2014, 05:45   #6
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Re: New VHF antenna cable, one piece or two/

Quote:
Originally Posted by Wotname View Post
Certainly put in a connector in the cabin after the coax exits the mast. If nothing else, this becomes a good disconnect point if you are ever troubleshooting the radio or antenna system.

If you can get them, use "N type" connectors rather than PL 259 / 258. If you have the tooling, use crimp connectors otherwise use solder ones. These really only solder the centre conductor while the braid is secured with a screw clamp arrangement.

In fact, use any coax connector (say BNC or TNC) in preference to PL 259 / 258.
-1 about the need for a connector there, but +1 on everything else, especially crimp connector vs. solder. A crimp coax connection done with the proper tool is far easier and far more reliable than soldered.

If you need to troubleshoot radio or antenna, why would you need to disconnect at the mast base? Just disconnect right at the radio.
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Old 16-11-2014, 08:04   #7
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Re: New VHF antenna cable, one piece or two/

Thanks all for the replies.

- For cable I already have RG213

- Drip loop at the masthead is in the plan.

- Life sometimes interferes with ones plans but baring unforeseen circumstances (I win the lottery and buy a new Moody) plan to keep the boat for many years.

- I can run the cable one piece all the way to the radio BUT there's a water tank in the way that forces the wiring and cables in that part of the boat to go under the sole and through inaccessible holes. I saved some old wiring just to pull anything new through that area. However I will have to do through that process again if I ever pull the mast. Not impossible, just a little extra hassle.

So the points seem to be

1. The loss would be small but at least not large.
2. Will add another connector and potential failure point.
3. If I add this connector use N instead of PL259.

Think I'm leaning towards keeping it one piece and will deal with the issue if I have to pull the mast.
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Old 16-11-2014, 08:13   #8
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Re: New VHF antenna cable, one piece or two/

I agree with other posts that the loss of a FUTURE connector near the
mast exit is not really significant. But the environment down there is usually tough so if & when you have to remove the mast I'd try to cut/ add connector 'above grade' close by. (leave some slack). In the mean time, I think it's worth the extra effort to do the initial install w/o mast step coax connectors... not so much about losing a little signal as it is for maximizing your long term reliability of a key safety item on your boat. It might be 20+ years before the mast is pulled!

By the way, DX Engineering has developed a new PL-259 coax connector that solders the easy center conductor and crimps/ heat shrinks the shield/ jacket. It does require purchase of a special crimping tool. (Just Google them if you want more info). If you use regular connectors I do recommend soldering the braid. It's not that difficult and ensures a longterm corrosion free connection in our harsh marine environment. It's a good idea to first measure center conductor to shield resistance of just the coax before you start (be aware some/ many VHF marine antennas if already connected at the other end will measure 'short' and is normal.). But if it's not connected or if you have a very sensitive ohm meter carefully measure that 'up to top' resistance and then touch the meter probes directly together... you should see a little difference. As you then insert the prepared coax into the connector with the braid folded back over some of the insert reducer there is some risk that a small piece of braid will short against the center conductor. By monitoring your progress with the ohm meter you can spot a problem before and after the 'no way back' soldering process. I find a 240 ish watt soldering gun makes short easy work of good solder flow to the exposed braid visible via the access holes of the connector barrel.

While your mast is out, I 'd recommend drilling an additional 1/2" - 3/4" access hole near the base and pulling in a fresh pull 'string' to the top. This will save much time / expense if you/ next owner ever needs/ wants to add off-air tv antenna, other instruments, radar, ... It's a good time to consider upgrading your anchor light/ steaming light to LED.


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Old 16-11-2014, 08:16   #9
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Re: New VHF antenna cable, one piece or two/

If you're using the RG213, you can use it and a gin pole to step the mast... thereby eliminating the crane expense...
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Old 16-11-2014, 08:27   #10
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Re: New VHF antenna cable, one piece or two/

Crimp vs solder. I think there is no question that the center conductor should be soldered but the braid? I read Maine Sail's article on the subject a couple of times and previous threads on the subject.

If I understand correctly, crimping the braid is easier and less likely to be done wrong by an amateur but done properly a solder/solder is better than the solder/crimp version?

That does seem to be the message reading between the lines of Maine Sail's how to article where he discusses using the solder/crimp when redoing connectors up the mast due to the difficulty of soldering in that position. From this I infer that if he had the option he would prefer soldering.

Since I already have a stock of Amphenol silver plated solder/solder connectors and the proper soldering tools I'm leaning that way.
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Old 16-11-2014, 08:35   #11
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Re: New VHF antenna cable, one piece or two/

Quote:
Originally Posted by HappyMdRSailor View Post
If you're using the RG213, you can use it and a gin pole to step the mast... thereby eliminating the crane expense...
Already got the mast stepping thing figured out. Dave (goboatingnow) is going to sell me a couple of skyhooks.
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Old 16-11-2014, 08:39   #12
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Re: New VHF antenna cable, one piece or two/

I have NO experience in marine electronics installation.

That said, why install a connector too soon? Since it appears the plan is to have all new wiring from the radio to the masthead, can't the existing wiring be used to pull a new cable from the mast step through to the radio? (I'm imagining the mast being re-stepped with 25'+ of cable at the bottom.)

Leave sufficient excess/slack cable at the mast for future use and buy the connectors and put them in the spare parts kit. If you need to pull the mast sometime in the future, THEN cut and install the connectors. In the meantime you have a single run.

I'd love to know what I'm missing and learn from it. I think the suggestions on connectors and installation tips are all great.
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Old 16-11-2014, 08:46   #13
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Re: New VHF antenna cable, one piece or two/

Quote:
Originally Posted by W3GAC View Post
I agree with other posts that the loss of a FUTURE connector near the
mast exit is not really significant. But the environment down there is usually tough so if & when you have to remove the mast I'd try to cut/ add connector 'above grade' close by. (leave some slack). In the mean time, I think it's worth the extra effort to do the initial install w/o mast step coax connectors... not so much about losing a little signal as it is for maximizing your long term reliability of a key safety item on your boat. It might be 20+ years before the mast is pulled!

Thanks. I think this is the way I'm heading. Start whole and cut it in the future if I have to.

The mast step is in the bilge but the high spot. Just aft of the step I have a 3' deep sump, mostly filled with the water tank but enough room for many gallons of bilge water. If the water does reach the base of the mast I'll have more things to worry about than a wet connector.

By the way, DX Engineering has developed a new PL-259 coax connector that solders the easy center conductor and crimps/ heat shrinks the shield/ jacket. It does require purchase of a special crimping tool. (Just Google them if you want more info). If you use regular connectors I do recommend soldering the braid. It's not that difficult and ensures a longterm corrosion free connection in our harsh marine environment. It's a good idea to first measure center conductor to shield resistance of just the coax before you start (be aware some/ many VHF marine antennas if already connected at the other end will measure 'short' and is normal.). But if it's not connected or if you have a very sensitive ohm meter carefully measure that 'up to top' resistance and then touch the meter probes directly together... you should see a little difference. As you then insert the prepared coax into the connector with the braid folded back over some of the insert reducer there is some risk that a small piece of braid will short against the center conductor. By monitoring your progress with the ohm meter you can spot a problem before and after the 'no way back' soldering process. I find a 240 ish watt soldering gun makes short easy work of good solder flow to the exposed braid visible via the access holes of the connector barrel.

Excellent procedure. Will be installing the masthead connector on the ground with access to both ends of the cable so can follow this technique. Was wondering if there was a way to check the results before stepping the mast.


While your mast is out, I 'd recommend drilling an additional 1/2" - 3/4" access hole near the base and pulling in a fresh pull 'string' to the top. This will save much time / expense if you/ next owner ever needs/ wants to add off-air tv antenna, other instruments, radar, ... It's a good time to consider upgrading your anchor light/ steaming light to LED.

One step ahead of you here. Already have the second hole and have a piece of parachute cord I was going to run in with the new wires.

But this is just for me. Who cares about the next owner?

Only kidding since the next owners might be my daughter and son-in-law, unless they decide to go with a new, big, fancy cat.
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Old 17-11-2014, 02:37   #14
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Re: New VHF antenna cable, one piece or two/

If you don't already have a wifi antenna installed, if you are going thru all the trouble to run new VHF antenna cable you might as well run CAT-5 Wifi cable at the same time. You can always install the antenna and router at a later date but at least the hard part is done.
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Old 17-11-2014, 03:06   #15
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Re: New VHF antenna cable, one piece or two/

Quote:
Originally Posted by Dockhead View Post
-1 about the need for a connector there, but +1 on everything else, especially crimp connector vs. solder. A crimp coax connection done with the proper tool is far easier and far more reliable than soldered.

If you need to troubleshoot radio or antenna, why would you need to disconnect at the mast base? Just disconnect right at the radio.
I agree that the bottom of the keel stepped mast is a bad place to put a disconnect point and if the back of the radio is easily accesible, then there is no need for a disconnect for testing.
I'm thinking more when the radio is nicely built into the panelling of the boat and is fairly inaccessible, an accessible connector is nice to have.

I have a RG400 tail from the radio about 1.5 metres long terminated into a bulkhead connector. The RG213 from the mast also terminates at the same connector. This is mounted above the chart table and allows for both testing and also for connecting the handheld radio quickly to the mast antenna or conversely, connecting the fixed radio to an emergency antenna.

YMMV
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