Good coax both for low VHF loss and corrosion

[svlamorocha]

Hello everyone

Unfortunately I discovered that the (untinned) copper shield of the RG-8X VHF coax that goes inside the mast has gone black...

Immediate root cause is that the PVC (not PE) cover was damaged by a genoa sheet between in the exposed area close to the mast step on deck (between the place where it comes out of the mast and the place where it goes through the deck.). Separate post on that.

Now that I will need to climb up the mast to replace the coax, can the experts please recommend a good make/model of coax that is good both from RF standpoint and corrosion resistance? Ideally I would like coax that is tinned...

Thanks in advance

Charlie

[btrayfors]

Originally Posted by svlamorocha

Hello everyone

Unfortunately I discovered that the (untinned) copper shield of the RG-8X VHF coax that goes inside the mast has gone black...

Immediate root cause is that the PVC (not PE) cover was damaged by a genoa sheet between in the exposed area close to the mast step on deck (between the place where it comes out of the mast and the place where it goes through the deck.). Separate post on that.

Now that I will need to climb up the mast to replace the coax, can the experts please recommend a good make/model of coax that is good both from RF standpoint and corrosion resistance? Ideally I would like coax that is tinned...

Thanks in advance

Charlie

Charlie,

If you can run the larger size coax, then RG-213 or RG-214 are excellent choices. LMR400 even better.

If you can only run the smaller size similar to RG8X, then choose RG8X marine (C8X). This cable has a tinned center conductor and a 98% tinned outer braid.

A good source is The RF Connection located in Gaithersburg MD. Their website is: The RF Connection Home Page

They have all the necessary connectors, and can make up the cable for you in any length, complete with connectors attached. If you're not very familiar with soldering on UHF connectors like the PL-259, it's a good idea to let the experts do it for you. This is a critical part of the system.

Bill
WA6CCA

[CarlF]

If you want to stay with the smaller wire, LMR-240 is tinned and not that much more costly than 8x.

In the large size LMR-400 Ultraflex is tinned and much easier to pull. The extra cost for one mast is small. But I'd be worried about puling the larger cable unless you are going to unstep the mast.

Definitely agree that someone else should put on the coax connectors. Find someone who claims to be very experienced in making them weathertight. A bad connector is worse than cheap coax. Don't trust the guy at the boatyard to do it either.

[svlamorocha]

Originally Posted by btrayfors

Charlie,

If you can run the larger size coax, then RG-213 or RG-214 are excellent choices. LMR400 even better.

If you can only run the smaller size similar to RG8X, then choose RG8X marine (C8X). This cable has a tinned center conductor and a 98% tinned outer braid.

A good source is The RF Connection located in Gaithersburg MD. Their website is: The RF Connection Home Page

They have all the necessary connectors, and can make up the cable for you in any length, complete with connectors attached. If you're not very familiar with soldering on UHF connectors like the PL-259, it's a good idea to let the experts do it for you. This is a critical part of the system.

Bill
WA6CCA

Thank you very much! I can solder anything in my home shack but the boat is far away and I will ask those guys to install the connector that goes in the antenna. I have no interest in going up again to solder up there! I will have to install the one at the radio end because the connector will not fit in the conduit inside the mast, but that is not critical.

Thanks again

Charlie

[svlamorocha]

Originally Posted by CarlF

If you want to stay with the smaller wire, LMR-240 is tinned and not that much more costly than 8x.

In the large size LMR-400 Ultraflex is tinned and much easier to pull. The extra cost for one mast is small. But I'd be worried about puling the larger cable unless you are going to unstep the mast.

Definitely agree that someone else should put on the coax connectors. Find someone who claims to be very experienced in making them weathertight. A bad connector is worse than cheap coax. Don't trust the guy at the boatyard to do it either.

Many thanks. There is no space for fat cable. There may be no need either because the mast is short (33 foot boat), hence attenuation is not a big deal provided there is no moisture or bad connectors.

Thanks again

Charlie

[Sailorman Ed]

So for about a 75 foot run, LMR-240 (least cost), RG-213U, LMR-400 or LMR-400DB (highest cost) ? Looks like I will be pulling the mast so replacing the cable now makes sense AND I can relocate the VHF into the cockpit. Does the center being stranded vs solid make a difference here?
Ed

[cortezsailor]

Great advice this helps me as well


Sent from my iPad using Cruisers Sailing Forum

[Ziggy]

Another good source of marine-grade coax is Amateur Radio Supplies: All Marine Grade Coax

[ka4wja]

Ed, Cortezsailor, Ziggy, et al,
1) First and foremost, there is a wealth of detailed (and even brief) info on this subject right here on Cruiser's Forum, and I'll add the links to these recent discussions below...


2) Secondly, here's the brief skinny!

a) If you can fit a 0.405" diameter coaxial cable from masthead, thru to where your VHF radio is (or will be), and can dal with running this size cable, then....use a good quality (name brand) RG-213 coax...such as Belden, DavisRF, Commscope, Times, etc....
Use quality connectors, and have them properly installed, and weather-proofed!!
Doing this, you'll be good for 20 years or more!! With no worries....

Originally Posted by Sailorman Ed

So for about a 75 foot run, LMR-240 (least cost), RG-213U, LMR-400 or LMR-400DB (highest cost) ? Looks like I will be pulling the mast so replacing the cable now makes sense AND I can relocate the VHF into the cockpit. Does the center being stranded vs solid make a difference here?
Ed

b) If you cannot fit this 0.405" cable, then use Times LMR-240UF.....(or in a pinch, Belden RG-8x)....
Note that the LMR-240UF uses a stranded copper center conductor....and that any "LMR" cable that is not suffixed "UF", will have a solid center conductor (as the LMR-400 and LMR-400DB, have a solid, copper-clad, aluminum center conductor)....

c) If you wish to curse the day you decided to change your VHF cable, just try pulling LMR-400, thru your mast and bilges!!
In addition to it being stiff and not able to be "kinked" at all, it is not really a good cable for any "unsupported vertical runs"...
In actual fact LMR-400 is one of the worst choices for our VHF marine antenna systems on our sailboats...
(LMR-400UF is fine....but it is still big and stiff...)




3) Third....
The difference is cable loss, RG-213 vs. RG-8x, vs. LMR-240uf....for a 75' length is actually pretty damn small!!

If you read the other threads I'm going to reference below, you'll see that the extra db to db and a quarter, you may pick up, will not be noticed in real use...(as long as you're not considering using RG-58!! Which is NOT acceptable for this application...)

75' of Belden RG-8x ~~ 3.4db
75' of LMR-240UF ~~ 2.25db
75' of Belden RG-213 ~~ 2.1db

BUT...
But, what IS noticed is the difference between old, moisture laden coax, with corroded connectors, etc. and a new cable, with new clean connections!!!



http://www.cruisersforum.com/forums/...ge-149499.html

http://www.cruisersforum.com/forums/...ml#post1802846

http://www.cruisersforum.com/forums/...ml#post1887668

http://www.cruisersforum.com/forums/...ml#post1682529

http://www.cruisersforum.com/forums/...ml#post1882988

http://www.cruisersforum.com/forums/...ml#post1883519

http://www.cruisersforum.com/forums/...ml#post1876295



I do hope this helps...

Fair winds..

John

[Maine Sail]

Originally Posted by svlamorocha

Hello everyone

Unfortunately I discovered that the (untinned) copper shield of the RG-8X VHF coax that goes inside the mast has gone black...

Immediate root cause is that the PVC (not PE) cover was damaged by a genoa sheet between in the exposed area close to the mast step on deck (between the place where it comes out of the mast and the place where it goes through the deck.). Separate post on that.

Now that I will need to climb up the mast to replace the coax, can the experts please recommend a good make/model of coax that is good both from RF standpoint and corrosion resistance? Ideally I would like coax that is tinned...

Thanks in advance

Charlie

I have found that Times LMR-400 (UF version) holds up extremely well if terminated properly. Braid is tinned and the jacket is very thick & durable. I use Amphenol solder/solder PL-259's with it and adhesive mil-spec heat shrink..