H155 antenna cable

[Plevier]

I think I've identified my antenna cable as H155 (see thread http://www.ybw.com/forums/showthread.php?394291-VHF-antenna-questions)
It's not a cable I've encountered before but looking up its specs, it seems to have a lot going for it - it's small, low loss, high power rating etc.
Anyone any experience of it? Comments good or bad?
The dielectric is PE foam, I guess that's how the size is kept down. Does it have drawbacks compared with solid dielectric? I presume it is a closed cell foam, and anyway once damp gets in you're stuffed whatever sort of cable it is!

 

[lw395]

I think I've identified my antenna cable as H155 (see thread http://www.ybw.com/forums/showthread.php?394291-VHF-antenna-questions)
It's not a cable I've encountered before but looking up its specs, it seems to have a lot going for it - it's small, low loss, high power rating etc.
Anyone any experience of it? Comments good or bad?
The dielectric is PE foam, I guess that's how the size is kept down. Does it have drawbacks compared with solid dielectric? I presume it is a closed cell foam, and anyway once damp gets in you're stuffed whatever sort of cable it is!

The Belden data sheet doesn't seem to give a power rating?
Loss is quoted as about 12dB/100m at VHF, which is OK IMHO.
The issues might be:
1) the inner and braid are tinned, silver plating lasts longer.
2) it depends on an ali foil under the braid, this works great as long as it stays dry.
3) There are quality makes like Belden, then there are all sorts of cheap 'compatible' imitations which may be much higher loss or not so well matched to 50 ohms. Most people won't worry about that as few applications use 20m lengths like boats do.

Any RF cable needs to be well sealed against humidity let alone rain or seawater, but this small stuff is probably more susceptible.
However a well made cable of this stuff might be better than a bigger cable fitted with those rubbish PL259's that don't seal the cable against moisure.
RF flows mostly in the surface of a conductor (skin effect), so any tarnish or oxide layer can put the loss up dramatically.

I'd mostly be concerned about the power rating and getting the right connectors, sealing etc.
Remember marine VHF can transmit for minutes at a time, while a moble phone signal tends to be short bursts, you need a continuous power rating, but OTOH, it's going in a cold yacht mast, not a duct with a bunch of power cables at 60degC.

 

[Plevier]

Thanks.
According to http://www.mondoplast.ro/eng/50ohm-coaxial-cable-Belden-H-155-pg_ft-1729 power rating is 210W at 144MHz - much the same as RG58. It has a much heavier core than RG58.
This site http://highfields-arc.co.uk/beginner/coaxexp.htm rates it at 240W as does this one http://www.qsl.net/dk3xt/cable.htm
Where on earth do you get cable with silver plated braid/core?
Yes most PL259 plugs are vile. Where can you get a decent sealed one - preferably without that horrible soldering job of the braid to the body through one of those holes?

 

[lw395]

I use plugs from Radiall, Suhner, Rosenberger, etc etc.
At VHF, I would probably get a pl259 to SMA or BNC adaptor, to suit whatever decent connector I sourced for the cable.

Companies like RS, Farnell, Pasternack, will give you an idea of what's available.
In small quantities or outside the trade, eBay may be easiest, there are suitable crimp SMA's on there, and SMA/PL259 adaptors.
Gigatronix have made similar cable for me.....