Which VHF Coax cable?

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Smee_Bruce

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I'm about to replace my VHF antenna and cable. I will need a run of 28m split 20m (mast) and 8m(below deck). I want to comply with ISAF Category 1 which states...

"the following types and lengths of co-axial feeder cable will meet the requirements of OSR 3.29.1 (b)(ii): (a) up to 15m (50ft) - type RG8X ("mini 8"); (b) 15-28m (50-90ft) - type RG8U; (c) 28-43m (90-140ft) - type 9913F (uses conventional connectors, available from US supplier Belden)"

From what I can tell (and I'm no expert) there is RG8U, RG-213 and my searching has turned up Ecoflex 10 (and 10 plus and 15).

Ecoflex looks interesting but I see little information about using it on a yacht.

Can anyone offer any advice on coax cable and whether Ecoflex may be a good solution.

Many thanks
Rob
 
Yes, RG8U is probably your best choice. Look for a stranded and tinned copper core and tinned copper braid. Braid coverage should be more than 90%.
RG213 is the same diameter and performance but with better insulating. Both are 9.5mm cable.
Attenuation - line loss - should be below 3dB per 100' at 150 mhz to meet ISAF Cat 1 specification over 85' or so.

Ecoflex, as far as I know, is plain copper core and braid so not really suitable. I don't know about its attenuation.
 
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I've just installed a run of RG213 - feels like garden hose compared to the skinny stuff that was there before! Hopefully this means it will be good. The supplier claims 98% braid coverage.

Got a Salty John aerial on one end and a brand new Standard Horizon on the other, so people should be able to hear me :)

Pete
 
Many thanks for all the helpful replies. Salty John, I think you are right, ecoflex is not tinned, so looks like the RG213 is the one I will go for.

Pete, did you go for armoured? I see they do it, but it should be protected in the mast and below deck - certainly no UV problems - so I'm thinking not really necessary. Got a good supplier?

Thanks again,
Rob
 
I would recommend Nevada Radio as well (being local to me)...

Don't be caught out by their 'Per length..' prices for buying by the meter.... The 'Per length..' usually refers to a 5m length :)

FWIW I have just read the same requirements. ISAF 3.29.1b actually states that your feeder cable must not have more than 40% power loss. The cable suggestions in green are recommendations but to be honest I thought that the RG8U was a military spec that has not actually been in use for years....

Nevada do appear to have the RG213 (equivalent to RG8U) but I have just personally installed a length of their Aircell 7 cable. Loss is similar at 144 Mhz, better at higher frequencies (such as Satellite phone antenna cable) and it's only 7mm instead of 10mm diameter. I only had a 23m run so perhaps worth re-doing the calculations for your run.

Aircell 7 is also a lot lighter and has a 19 strand core rather than the usual 7 strand core making it more flexible and it is supposed to be UV resistant.

As Nigel says - Keep the water out or any VHF cable will become more lossy.

When installed - Try to find a local radio amateur who can do an antenna test for you (with their own equipment as source) and an SWR and power test (using your VHF as source) for peace of mind.

As to the actual aerial - Most chandleries stock aerials that have cables fitted by just pushing the prepared cable into the base.. Nevada only sell aerials (marine and Ham) that appear to have sockets that take the PL259 plugs. It's one consideration otherwise it's a nightmare getting a 10mm cable into a 5mm hole!
 
The ISAF cat 1 requirement is for no more than 40% line loss.
A 40% loss is around 2.4 db. RG213, and RG8U, loss is around 2.20 db at 150 MHz for 30m.
It isn't rocket science. If you use a lower spec cable you won't meet the ISAF requirement.
I would not use a non-tinned copper cable - either coax or electrical cable - in a marine environment, wicking of moisture back from your connectors will corrode copper, but not tinned copper. But a tinned conductor is not an ISAF requirement - they don't address the subject. Others such as AYBC, UL and the US coastguard do - but there is no obligation under ISAF rules to use tinned cable.
 
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