Thursday, 7 February 2013

Antenna maintenance

Over the past few days or so I had noticed that the performance of my HF wire antenna (the Western HF 10) had changed. The SWR was higher than usual where it was resonant on parts of 80, 20 and 10 metres the SWR was now 3:1. The rigs auto ATU still tuned it ok on most bands but the receive seemed a little down too.
A physical inspection of the antenna itself showed nothing obviously wrong. I then disconnected the Coax feed at the antenna end and replaced the antenna with a dummy load. The dummy load showed 3:1 SWR. So the fault was in the coax or maybe the PL259 plug. Not surprising perhaps in view of the very heavy rain and substantial snowfall we have had here over the past month.
So out came the soldering iron and off came the PL259.

You may just be able to make out the corrosion on the plug in the picture, the body of the plug also looked a little bit tarnished. It seems water had found its way in even though the plug had been given a good covering with self amalgamating tape. Luckily trimming the coax back a few centimetres showed that water had not got that far. A new plug was soldered on and reconnecting, weatherproofed as much as possible and the antenna was back to normal! Thankfully an easy fix.


  1. Lucky you noticed the changes to the SWR before the things got any worse, it’s a shame though that manufacturer’s still use these horrible connectors as it has long been known that are a pain to waterproof and assemble.

    When I have to I use the pressure sleeve type which are a vast improvement but are still nowhere as good as N connectors or TNC’s.

    Kevin G6UCY

  2. I too have had some odd SWR issues and it all came down to PL259's and one thing I have done in the past is removed the coax from the rig and antenna. I use my Fluke meter on the ohm's scale and go from centre to braid. If I get any reading (most times in the mega ohms) both PL259's are changed. This has worked great for me.

  3. The SO-239 / PL259 connectors are not remotely waterproof. They are not really suitable for outdoor use, unless you are a fan of wet co-ax and corrosion. It seems odd then, that most commercially made radio aerials still use them. I guess its all down to keeping things cheap. The compression type N Connector is a water resistant connector as so is a better choice for outdoor connections.

    73 Al. GM1SXX

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