Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 23-04-2015, 10:21   #1
Registered User

Join Date: Jun 2009
Location: still in a roll of fiberglass around Cape Town
Boat: Leopard 40 (new model)
Posts: 1,202
Good coax both for low VHF loss and corrosion

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
__________________

__________________
svlamorocha is offline   Reply With Quote
Old 23-04-2015, 16:02   #2
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,038
Images: 4
Re: Good coax both for low VHF loss and corrosion

Quote:
Originally Posted by svlamorocha View Post
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
__________________

__________________
btrayfors is offline   Reply With Quote
Old 23-04-2015, 16:26   #3
Registered User

Join Date: May 2008
Posts: 1,971
Re: Good coax both for low VHF loss and corrosion

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.
__________________
CarlF is offline   Reply With Quote
Old 23-04-2015, 16:44   #4
Registered User

Join Date: Jun 2009
Location: still in a roll of fiberglass around Cape Town
Boat: Leopard 40 (new model)
Posts: 1,202
Re: Good coax both for low VHF loss and corrosion

Quote:
Originally Posted by btrayfors View Post
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 is offline   Reply With Quote
Old 23-04-2015, 16:46   #5
Registered User

Join Date: Jun 2009
Location: still in a roll of fiberglass around Cape Town
Boat: Leopard 40 (new model)
Posts: 1,202
Re: Good coax both for low VHF loss and corrosion

Quote:
Originally Posted by CarlF View Post
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
__________________
svlamorocha is offline   Reply With Quote
Old 06-10-2015, 13:30   #6
Registered User
 
Sailorman Ed's Avatar

Join Date: Jun 2010
Boat: Polynesia 40/42
Posts: 685
Images: 15
Send a message via Skype™ to Sailorman Ed
Re: Good coax both for low 75 ft VHF

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
__________________
Sailorman Ed is offline   Reply With Quote
Old 09-10-2015, 20:25   #7
Registered User
 
cortezsailor's Avatar

Join Date: Feb 2011
Location: Cortez Island BC
Boat: Corbin 39
Posts: 163
Re: Good coax both for low VHF loss and corrosion

Great advice this helps me as well


Sent from my iPad using Cruisers Sailing Forum
__________________
cortezsailor is offline   Reply With Quote
Old 09-10-2015, 20:41   #8
Registered User
 
Ziggy's Avatar

Join Date: Apr 2008
Location: U.S., Northeast
Boat: Contessa 32
Posts: 1,421
Images: 2
Re: Good coax both for low VHF loss and corrosion

Another good source of marine-grade coax is Amateur Radio Supplies: All Marine Grade Coax
__________________
... He knows the chart is not the sea.
-- Philip Booth, Chart 1203
Ziggy is offline   Reply With Quote
Old 10-10-2015, 17:36   #9
Registered User
 
ka4wja's Avatar

Join Date: May 2007
Location: Florida
Boat: Catalina 470
Posts: 2,033
Re: Good coax both for low 75 ft VHF

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....
Quote:
Originally Posted by Sailorman Ed View Post
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!!!



VHF and AIS Radiowave Propagation and VHF and AIS Radio Range

Antenna recommendation

Coax: - solid, untinned center conductor?

Pull VHF cable through mast

Top of mast, or RG213.... cant do both!

Connecting VHF, AIS, GPS - NMEA0183 and NMEA2000

AIS Antenna on Spreaders



I do hope this helps...

Fair winds..

John
__________________
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110
ka4wja is offline   Reply With Quote
Old 10-10-2015, 17:49   #10
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Good coax both for low VHF loss and corrosion

Quote:
Originally Posted by svlamorocha View Post
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..
__________________

__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Reply

Tags
corrosion, vhf

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Coax cable loss sdrformariners Marine Electronics 0 11-03-2014 03:16
Vhf coax, if it aint broke...? Ketchgould Marine Electronics 41 15-11-2013 19:52
VHF Coax CampDavid Marine Electronics 22 06-12-2011 11:58
Coax for VHF StringBimini Marine Electronics 27 08-01-2011 07:01
Testing VHF Coax cable MV Marine Electronics 15 14-05-2008 18:59



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 05:44.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.