Installing a VHF cable/Antenna in the mast

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Alfie168

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I have acquired a VHF radio to install on Seronera, my Dehler 22. Now all I have to do is install an antenna and some coax cable inside the mast. Are there any guidance notes as to how to do this e.g. what grade of coax cable is most suitable, what is the most suitable antenna...recommendations for a through deck connector..etc etc.

Any advice welcomed before I try reinventing the wheel.

Tim
 
Different people will have different favourite aerials, I like the Vtronix whip with built in windex.
Cable should be 50ohm coax, may be supplied with the aerial. RG58 is a suitble type, about 7mm diameter. The cable can be quite pricey, particularly the best subtypes, which have silver plated braid and centre conductor. Keep the cable dry with the ends sealed and it will last a lot longer. Corrosion of the braid can increase the loss horribly.
I would avoid a connector at the foot of the mast in favour of a cable gland which dismantles to let the connector through, so that you have one piece of cable going right to the masthead.
Make sure the cable does not rattle about in the mast, it will drive you mad! Some people use cable ties at 50cm intervals, with long tails to stop the cable moving in the mast. Some masts have a conduit. You need to be fairly sure that halyards aren't chafing the cable.
Hope that helps.
 
I'd use RG8X (6.2mm) which is a good compromise between RG58 (5mm) and the heavier RG8U and RG213, both 10.3mm.
RG58 loses 5db per 30m, RG8X loses 3.5db and RG8U loses 2.2db. (Use marine quality, tinned core and braid).
Obviously the heavier the cable the less flexible it is and the more difficult to thread through the mast and boat.
If you can run the cable through a deck gland without a joint at deck level this is better because you'll have one less potential loss. Look at the Index Marine site for a variety of good deck glands. One that allows the pl259 connector (for the radio) to be pulled through without having to remove it from the cable allows you to drop the mast without remaking the pl259 joint each time.
Vtronix and Glomex make adequate masthead whips. My favourite is the Metz because I sell them. And they are the best.
 
Antennae come in the form of 1/4 wavelength ie about 17 inches of SS rod or similar or 5/8 wavelength ie around 40 inches long usually in a fibreglass tube. The longer type have greater gain in that they focus the signal more in the horizontal plane they also usually do not need an earth connection so are suitable for fibreglass deck. This is great for power boats but can mean that it is not good on a sail boat that is heeling over. The 1/4 wavelength type should be fine for mast head where you don't want a long antenna.

I have and prefer an antenna on the pushpit on your sized boat. I drop the mast often so don't want antenna connections at the mast base. I use a home made antenna which works extremely well though I don't tend to demand the greatest range from it. PM me if you want to try one. olewill
 
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