Coaxial cable choices for the run inside the mast

[Jammer]

I've never understood why people don't run Heliax inside the mast and for any other lengthy coax runs they may have.



I like the 3/8" FSJ2-50 which is 8 pounds per 100 feet, 1.5 dB loss per 100 feet in the marine band. Performs like LMR-400, similar weight, but without the corrosion problems as it's all copper (no aluminum).


There are 1/4" and 1/2" versions with a tradeoff in weight and price vs. loss.


Can't imagine that LMR-type cables do well in a marine environment but people use them. Maybe they last long enough and people just replace them every 5-10 years. Heliax would outlast the mast.

[ohgary]

Originally Posted by Jammer

I've never understood why people don't run Heliax inside the mast and for any other lengthy coax runs they may have.

.

Assuming you need to make no turns hardline is ok but a bit pricy for the gains. Now if you ran hardline up the mast, but a bulkhead connector in the mast then ran a short jumper cable to the antenna and cable to radio that might work but again. gain for cost isnt there.

[Brian.D]

If you want to use hardline, fine. But they call it hardline for a reason. Be prepared to purchase tools for the connectors. Installing the hardline in the mast will require the mast to be down. Drilling holes should be no problem but the connects for hardline are expensive. I cannot see the delta between attenuation and cost being worth using hardline.

I would highly recommend either Belden 9258 (RG8X) or LMR-240 as your cable of choice. You might find better like RG8, Belden RG213, or even LMR400. A little heavier than the -8X or -240.

Your choice.

[Jammer]

Brian,


Is it your experience that the aluminum conductors in LMR-xxx cable hold up well over the years, on a boat?

[Brian.D]

My personal choice is Belden, not LMR. I have read that LMR center insulator is susceptible to moisture issues. Sorry, I cannot find the link now but I will keep looking. However, I don't have issues with the Belden copper when it is sealed properly. Double wall heat shrink over the cable and barrel, then amalgamated electrical tape over the remaining exposed connector.

The last time I played with hardline was at a MARS station in the 80s.

[SoonerSailor]

Problems with moisture and regular coax seem to be limited to inadequate seal at the coax to antenna connector. It’s not hard to get a hermetic seal using the right products. My RG-213 in mast coax is 16 years old with no sign of electrical degradation that moisture would cause, as tested with open/short/load analysis at VHF frequencies with a Rig Expert antenna and transmission line analyzer.

[S/V Illusion]

I’ve regularly used hardline on every ‘run’ up my ham radio tower as well as other antennas. I never bothered with the boat HF or VHF antennas as the ‘run’ isn’t long enough for me to rationalize the extra connections just to get the trivial ERP increase.

The mechanical connections seem to survive years outdoors but periodic inspection is necessary to ensure integrity - something which is difficult inside a mast.