Coax Cable

malexander · Mar 1, 2011

I've got about 100' of RG-213U that I could let go of if you are interested

Fred Villiard · Mar 1, 2011

You would be better off using Times Microwave LMR-400 or LMR-400 Ultra Flex.

Less loss, and the foam dielectric is a closed cell, and the foil is bonded to it, this keeps
moisture from migrating, which 213 is notorious for.

Fred Villiard
Sr. Signal Integrity Engineer

Bill Roosa · Mar 1, 2011

coax comparison

The Ru-213 is a 50 ohm cable the others to you mentioned are Rg 213 types, aka different manufacturers but the same cable. The attenuation / 100 ft is over 3.5 db at 160 MHz (one of the worst cables) so you are going to be loosing over 1/2 of your power if you use 100 ft of cable.
I'd recommend either lowering the antenna to the rail and preventing the power lost or going to RG-8 or Benden 9913 for a mast head mount. RG-8 has only 2.2 bd/100ft at 165 MHz so it is substantaly better but not anything to write home about.
Your line of sight will not be degraded that much by lowering the antenna but you will notice that 1) you don't get as much static noise down low upon reception, and 2) you will be able to get out a stronger signal and blast through the noise to other radios.

IMHO, moving the antenna would be your best move.

Fred Villiard · Mar 1, 2011

Bill, LMR-400 is 1.5dB per 100 ft at 150 MHz, LMR-400 Ultra Flex is 1.8 dB, RG-213 is 2.44 dB, RG-8U is 2.43 dB, RG-8X is 4.54 dB. The main reason that I mentioned the LMR cable is the closed cell foam dieletric and the bonded foil, much better moisture resistance.

Fred Villiard

rpwillia · Mar 1, 2011

VHF is Line of Sight

Seems the antenna works best up high on the mast. Sounds like the LMR-400 is the way to go.

bigmuffin · Mar 1, 2011

Here's a great how-to link from Mainesail on the connectors.
http://www.pbase.com/mainecruising/vhf_cable

I think the lmr-400 ultraflex (not the lmr-400 regular) has bigger shielding than some of the other cables, so if you do use it, the connecters you need are going to have to be a slitghly bigger size.

Maine Sail · Mar 1, 2011

rpwillia said:
Seems the antenna works best up high on the mast. Sounds like the LMR-400 is the way to go.

VHF is line of sight and The Times LMR stuff is really good. It's what all the Ham guys I know use and trust.. Just wish they'd told me about it before I ran the Ancor RG-213 up my spar...

Don S/V ILLusion · Mar 2, 2011

Not sure which antenna you will be using but most antennas and all VHF radios require PL259 connectors. Since you are going to the trouble, you might want to do it right and use good solid dielectric gold plated connectors and stay away from the crimp-type ones which is never a good idea for coax.

Even in the best circumstances crimping can deform the dielectric and fail sooner than properly soldered connectors. Crimping is often used by so-called professional installers who don't know how to solder, don't want to bother, don't have the solder tools or just want to get it done quick to get to the next job.

Fred Villiard · Mar 2, 2011

Don is right most radios and antennas will use the PL-259. Be sure that the plug dieletric is Teflon, gold plating is okay, but silver plating is just as good. Steer clear of nickel and tin plating, a good one is Amphenol p/n 83-822. the only reason to steer clear of the nickel plating is they are hard to solder if you are not in the very good graces of the solder gods.

Fred Villiard

Maine Sail · Mar 2, 2011

Don S/V ILLusion said:
Not sure which antenna you will be using but most antennas and all VHF radios require PL259 connectors. Since you are going to the trouble, you might want to do it right and use good solid dielectric gold plated connectors and stay away from the crimp-type ones which is never a good idea for coax.

Even in the best circumstances crimping can deform the dielectric and fail sooner than properly soldered connectors. Crimping is often used by so-called professional installers who don't know how to solder, don't want to bother, don't have the solder tools or just want to get it done quick to get to the next job.

I agree on solder at least the pin. Many of my friends who do HAM stuff, I do not but I trust their advice, have made the move to crimp & solder connectors and my local electronics distributor sells a ton of these crimp/solder PL-259's to mostly HAM guys.

None of the guys I know are reporting any issues with them provided they are installed with the correct crimp tool. The draw back is that this is yet another tool to own but so is the proper soldering equipment. The pin end is soldered and the braid gets crimped. If you properly cover your connections with tape and adhesive heat shrink the risk of an issue is very, very small.

In the marine world I have actually seen a lot more failures of soldered pro and DIY made soldered PL-259's and it is rarely if ever the pin but usually the soldered braid.

My buddy Paul is really, really good with solder and I watched him toast a few PL-259's in the yard last spring due to wind. He was still a little unsure of the final one due to the wind. In order to solder outside you need the right conditions, especially if at the top of a spar, and this rarely occurs when you want it to.

While the full solder connectors are great the realities are that many folks just don't have the skill to solder the braid well through those tiny holes, out doors & with wind.

What ever you do do not use those Shakespere no crimp, no solder connectors..

I don't know much about this guy but was turned onto this article by a HAM guy at the local electronics shop. It is on eHam.net. I still feel more comfortable with a crimp/solder than a double crimp but I may come around...

http://www.eham.net/articles/19257

Don S/V ILLusion · Mar 2, 2011

The caution in crimping connectors on coax is particularly true for foam dielectric coax. It is completely impractical to get a tight crimp without cutting or deforming the dielectric and almost as difficult with solid dielectric. Conversely, if one doesn't know how to solder these connectors, it is likely the dielectric will melt and deform or one could create a "cold" solder joint so either way, there is no simple solution to a proper connection.

Shakespeare has recently come out with a new gold design PL259 with a ferrule which can be crimped without damage but it is only for the smaller RG58/RG59/RG8x types.

Most hams including me far prefer hardline coax which is a different animal requiring different connectors as it has much lower loss with the added benefit of being able to use mechanical connectors obviating all the issues above. Hardline would be ideal in the marine environment but for it's weight so it is limited primarily to power boats or sailboats with stern mounted antennas (not up the mast) as the best choice.

Blitz · Mar 2, 2011

Bob S said:
Thanks everyone! Great info and a lot to digest. I am buying the LMR 400 UF cable but had a question on connectors. Are these Type N connectors that mount into the radio and antenna?

Word of caution, I believe most (if not all) LMR 400 UF cable is not UV protected. Someone who might know can chime in here.

I'm doing the same project this spring.

Don S/V ILLusion · Mar 2, 2011

Bob S said:
Blitz,

Time Microwave says it was designed to be used outdoors and gives it a ten year life expectancy.

http://www.timesmicrowave.com/content/pdf/lmr/62-65.pdf

Don,

Are any of the connectors on page 2 of their pdf compatible to a PL259 connector?

I'm using a [FONT=Verdana, Arial, Helvetica]Metz Manta-6 Marine Antenna.[/FONT]

It is difficult to tell from their specs but the pictures appear to not be compatible.
If you are shopping around, one place to check is Cableexperts.com (sp?) but check the specs before buying. And follow Fred's advice regarding quality of the connectors which can make a big difference in both loss and longevity.

Forrest15112 · Mar 31, 2011

Hey, I was looking around at threads here and came upon this subject which I have some experience in. The absolute best thing for performance is antenna height, assuming no faults of course. The connection to the antenna, if it's a connector should be sealed. At marine VHF frequencies & power, it doesn't matter much in actual performance what type of connector you use, as long as it is installed properly. Crimp on connectors are fine as long as they're crimped with the proper tool. LMR400 is nice cable but at runs less than 100', it could be an expensive addition that will not produce a noticeable improvement in radio performance. As mentioned already, your RG213 has about twice the attenuation per 100' as the LMR400, but that is a negligible amount in actual performance. LMR400 @165MHz has about 1.3dB loss at 80'. The RG213 is at 2.1dB. You are only looking at <1dB difference. There is no way you will tell the difference in performance. The 213 is thinner, more flexible and cheaper. Connectors are cheaper too.
RF connectors aren't weatherproof and do need to be sealed. Some will perform better than others but all need to be sealed up if exposed to rain. A mast to deck mount on a trailerable boat obviously would be sealed with something removable like a rubber boot which isn't as effective as butyl rubber tape but isn't as permanent and can be inspected easily. If the antenna base requires a connector, a good permanent sealing method is to wrap the connector and a few inches of the cable with electrical tape. Then a wrap of butyl rubber tape, followed by another wrap of electrical tape. The butyl rubber tape is what is primarily used commercially. It sort of resembles tar but is very elastic and sticky. It isn't real messy though. Good luck and hope what I added helps.

Bill Roosa · Mar 31, 2011

Decibel math

You cannot add or subtract db and get a valid answer.
to wit: a 10 db loss and a 5 db loss are in the relationship of 1:2
the differance is 5 db which is a number very much greater than 2
a 100 db loss and a 105 db loss also have a differance of 5 db but they clearly do not represent a 2:1 ratio. so while Forrest is correct it is only a 1db differance that does not tell the whole story

Fred Villiard · Mar 31, 2011

The big differance between the LMR-400, LMR-400-UF and is longevity in adverse conditions Times rates the cable for at least 10 years, RG213 from Belden is rated for 5 year, this is not in salt air conditions.

As for connectors most of the marine antennas, VHF's, and SSB's have UHF female recepticals that need a PL-259 plug to mate with it. The standard PL-259 can be used on LMR-400, and LMR-400-UF you just need to open up the center contact with 1/8" drill, if you can not get the Times connector, which is like pulling teeth if you do not want a thousand. The reason I know about drilling the center pin out, our sister division makes the connector for Times, I'm in the cable assembly end and run the test lab.

Remember that dB is a log function, the 1dB extra loss does not sound like much but it is a 20% loss in power. As far as transmit goes that loss is negligible, but you have the same loss on receive that can make alot of differance trying to receive a weak signal.

I whole heartedly agree with Forrest, you have to be very meticulous with your connector installation and sealing, the key to crimping is the proper tool and adjustment, and proper tools are in the several 100$+ range.

Bill Roosa · Mar 31, 2011

See my DB math post above. I agree that a 1db loss (at the 1 db level) is 20%. I'm having issues with the "extra" part. Am I to infer that at the 5 db level adding 1 db more to get to 6 is a 20% increse in power loss (in our example)? Pretty sure that will not pass even the giggle test.
You cannot add and subtract db and get valid asnwers. db are ratios so you can say "more" or "less" but not quote an actual ammount till you calculate the two. You certianly cannot say mine is 10 and yours is 20 so mine is half of yours type stuff.
Another way of looking at it is this, a 1db change at the 1 db level is about 20% change in absolute value, a 1 db change at the 100 db level in either microscopic or huge debending on which way you are calculating it but is not 20%
so 2.1 db loss is almost a 80% increase in power disipated while going up/down the mast while a 1.2 db loss is around 20% so while you are receiving at the .1 MICRO watt level you either have .08 micro watt (1.2) or a .02 micro wat (2.1) power level at the receiver end. As Fred noted this is a pretty big differance.

Coax Cable

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