Antenna cable: through-deck connector or a gland?

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Pavel

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A dilemma for me: I'm installing a radio on a trailer sailor, so obviously, will be getting the cable through the deck. The plan was to use a gland to have the connection inside as is "right and proper"; now, the issue is that I wanna retain the ability to drop and raise the mast quickly, and it all becomes a bit bothersome with getting to the connection (likely to be hidden away between mouldings), undoing the gland, tapes and all that.
The question is, what's the people's view on deck connectors such as Glomex RA105, are they considerably worse than a bog-standard PL259 connection inside? I appreciate the obvious waterproofing issue, but is there anything else to consider? That's assuming that everything else is soldered equally well, all fittings waterproofed and so on.

Another question is about RG8X cable - as with everything else, having the words "marine grade" next to it pushes the price up literally threefold. I know the "you don't wanna be saving pennies on safety kit" mantra and that's fine, but what's the real difference between marine and the general purpose tinned RG8X? Stranded core? Braid coverage? UV resistance? Has anyone used the non-marine cable?

Thanks,
P
 
I have a deck socket for the antenna cable to my mizzen mast. Seems to work fine, and the inside where the actual mating conductors are is always bright and shiny when opened. The blanking plug is of course important to keep it that way when the mast is down.

Pete
 
Standard PL259 plug and deck socket.

No bother in 25 years!

Apply a little silicone grease to the boot on the plug so that it slides easily up and down the cable and also helps to keep it water proof.

Follow the fitting instructions carefully
 
I guess most of us have standard cable on our antenna, I believe most are fitted with this when you buy them. It should last best part of a decade. How you take it through the deckhead is a matter of which is suitable for your type of usage. As you say, a gland is probably the best, but a nuisance for regularly dropping the mast. A connector treated to regular inspection and maintenance is likely to suit you much better. Personally, I don't like the PL259 connectors I prefer 50 ohm BNC as they are less bulky. Deck connectors are available in both types.

Rob.
 
We had the same dilema on our ts. I settled for having a pl259 connector and deck gland. The 259 goes through the deck gland along with the 12v with crimped spade connectors for the mast light. I have found there is plenty of space under the headlining for a 259 barrel connector and 259 on the end of the cable to the vhf.

Deckgland is easily dismantled and resealed.

I prefer to keep any connections in the dry.

Ref cable, glands and connectors suggest you contact Salty John of this parish for sound advice and competive prices.
 
Bulgin waterproof BNC deck connector was perfectly successful on our previous boat.

The boat was twelve years old and I assume that the deck connectors were original. We had to replace a six way connector that was carrying the signals for the wind instruments and had leaked to the point where the pins had corroded, but the antenna connection was still fine.
 
Mine's through a deck plug and socket.

But NOT a PL259 / SO239, they are rubbish connectors really and in no way watertight.

Insted, mine has an N type socket in the coachroof, and an N type plug on the aerial cable coming out of the mast.

N types are much more professional connectors, and have sealing glands built into them, so even if the boot fails, they are more or less watertight when mated.
 
VicS said:
Standard PL259 plug and deck socket.

No bother in 25 years!

Apply a little silicone grease to the boot on the plug so that it slides easily up and down the cable and also helps to keep it water proof.

Follow the fitting instructions carefully
Click to expand...


Apologies it's not a PL259 ( found a fitting instructions leaflet and assumed it was for the deck socket and plug ..... not so)


Its a Vtronix coaxial deck plug and socket with N type connectors. No trouble and served the test of time

One of these: (See http://www.force4.co.uk/485/Vtronix-Coaxial-Deck-Plug---Socket.html)
230007.jpg


.
 
Thanks a lot everybody, that's jolly helpful. What about the cable, though? Methinks, as a compromise, a "land-based" cable inside the boat, where no flexing is expected (hence no need for a braided core and equally, no UV damage) and a "proper" cable through the mast?
 
Pavel said:
Thanks a lot everybody, that's jolly helpful. What about the cable, though? Methinks, as a compromise, a "land-based" cable inside the boat, where no flexing is expected (hence no need for a braided core and equally, no UV damage) and a "proper" cable through the mast?
Click to expand...

Dunno about the cable. My aerial came with cable attached. Cut it for the deck plug and socket and the used bit cut off to run internally to the set ( that's where the PL259 plug is!)

If I had to replace the aerial I'd opt for one with the cable attached again I think. Then there are no potential problems with connectors at the top of the mast.
Pleased with the aerial I bought. Not many last for 25+ years I suspect. Midlands Communications IIRC but they dont do VHF aerials now for little boats AFAIK
 
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Cable should be 50-ohm, whereas most 'land based' coax is 75ohm.
The best stuff has silver plated braid and core.
Water ingress often causes corrosion of the braid, which can seriously increase loss. Anything with black or green copper braid needs to go in the skip.

N type is good. PL259 is rubbish, but just about works at VHF frequencies, which are not really 'very high' these days. A quality connector will seal the cable.
note that there are many different types of N-type connector (likewise BNC) intended for different types/sizes of cable. RG58 is probably the most common cable type for boat aerials?
 
And make sure you understand how to terminate an N plug or socket.

In particular, when you dismantle the parts for the first time, note which order they go in, and which way round they go.

The previous owner of my boat got it spectacularly wrong. I'm surprised the VHF worked at all the way it was wrongly terminated.
 
Pavel said:
Thanks a lot everybody, that's jolly helpful. What about the cable, though? Methinks, as a compromise, a "land-based" cable inside the boat, where no flexing is expected (hence no need for a braided core and equally, no UV damage) and a "proper" cable through the mast?
Click to expand...

If you have a trailer sailor on which you regularly drop the mast and, therefore, have the opportunity to regularly check the connections and the condition of the cable the quality of the cable is less important, I guess.

Some thoughts on cable size here:http://saltyjohn.blogspot.com/2011/10/lets-talk-coax.html

Gordon West, in his book Marine Electronic, says the same thing - for masthead installations use RG8X and for very long runs use RG8U or RG213. RG58 is supplied crimped to some aerials but should only be used for short runs due the high signal loss of this type of cable.

PL259's are fine at VHF frequencies; they are simpler to fit than other types and are very rugged. You have such connections at the back of virtually all marine VHF sets - it's the industry standard connector. By all means use N types for making intermediate connections, it's a less bulky join that two PL259's and a barrel connector, but it's a fiddly job to attach, so take care.
You can make your own through deck or through bulkhead connection using a long, PL363, barrel connector. They come with two nuts, but you'll want to add a couple of large washers to give a nice seal on the deck.
 
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