Joining VHF coax.

JABS · 21 April 2011, 12:12

Hi,

As an interim solution, I need to splice a new piece of coax to my existing run.

It will eventually all be replaced.

Is it better to do a soldered joint sealed with heat shrink or to use two pl259 plugs? Which gives the lowest loss?

Thanks!

jyasaki · 21 April 2011, 17:05

Noise will be the big issue. VHF's can be sensitive to picking up noise from ignitions, and fishfinders.

As far as I know, you'll have an unshielded section if you use a standard "twist-and-solder" splice, which will be susceptible to interference (both coming and going.) There are ways around that (wrapping the insulated center conductor join with foil that shorts to the shield, etc.)

I would say that using a connector that preserves the shielding would be better - either PL-259/SO-239, or, alternatively, BNC connectors would be a good short term choice.

That said, if it's short term, a solder splice is cheaper, faster, and a lot easier.

jky

karlT · 21 April 2011, 17:24

2 * PL259 connectors with joining connector

on ebay will cost you about £2 company called Rocket Radio in Letchworth

BogMonster · 21 April 2011, 19:50

Quote:

Originally Posted by karlT

2 * PL259 connectors with joining connector

on ebay will cost you about £2 company called Rocket Radio in Letchworth

That is how I would do it too

nik · 21 April 2011, 21:01

There is no need to have an unshielded section.
Strip back the outer sheath on each piece by two inches.
Pull the screen back over the outer sheath.
Shorten each inner core by about an inch.
Strip back a bit of insulation on each inner core, solder together and insulate.
Now pull the screen over the joint, overlap and solder a piece.
Now insulate the whole joint.

sea_quest · 21 April 2011, 22:27

soldering will be a much better permanent fix, providing both core and briad are insulated from each other properly. connnectors will add a lot more noise as well as other problems in the future.

GJ0KYZ · 21 April 2011, 23:03

Quote:

Originally Posted by karlT

2 * PL259 connectors with joining connector

on ebay will cost you about £2 company called Rocket Radio in Letchworth

Agreed. It's how I've done it on my boat; all covered in Sikaflex to keep out da h2o.

Channel Ribs · 22 April 2011, 07:18

It is horses for courses I would say. If you go down the solder route then it is up to you to do a really proper job, done well it will be better than a pair of plugs; done badly and you are introducing a potential fault.

I have used PL259s mid cable run before and while they probably do reduce performance, I have never been able to detect it.

biffer · 22 April 2011, 07:38

there is another way, ave a look on shakespear airiel website, there is a coax connector, you just push the coax in the fittingfrom both end, a bit like plumbing pushfit connectors

Channel Ribs · 22 April 2011, 08:01

Quote:

Originally Posted by biffer

there is another way, ave a look on shakespear airiel website, there is a coax connector, you just push the coax in the fittingfrom both end, a bit like plumbing pushfit connectors

http://www.shakespeare-marine.com/co...ck=PL-258-CP-G

JABS · 22 April 2011, 08:36

Brilliant, thanks.

I think I will follow my instincts and solder it! Load of self adhesive heat shrink and it should last a few weeks.