Wednesday, 14 March 2018

Antenna connections: mind your material.

If you like ham radio, there's never long to wait before you need to repair or replace antenna connections.

For many, and that certainly includes me, it is often easiest and cheapest to make connections to, say, a balun by using ring or spade connectors that are widely sold for automotive and general purposes.

These connectors are very good, and usually made of plated brass or similar alloy.  They do, though, have poor mechanical strength, so any wire tension has to be taken by a relief loop, and not the connector. The connectors have good resistance to weather, but do corrode.

Last week, I was sending some signals on 10MHz with my half sloper for that band, connected to a 1:1 balun at the tower.  This wire is normally very well-behaved, but had recently started to produce brief SWR spikes, although these were not to very high levels.

The wire I used for this initially experimental antenna that became permanent was quite thin, multistranded stuff, but with a very heavy duty PVC coat.  I decided to change it, as SWR spikes usually indicate the wire starting to come apart within the PVC.

Probably OK, but stainless won't suffer this corrosion at all.


I haven't bothered checking if the wire really was decayed, but one thing is clear: the ring connector suffered quite a lot of corrosion after a winter out in the windy, salt-laden air of coastal Wales.

The part protected by a washer and nut was quite clean, but there was also a small part where insulating tape projected into the washer area (on the other side to the one in the photo).  This could have contributed to or caused a momentary loss of connection.  For some reason, I hadn't used the stainless steel ring connectors that I already had.

So if you are planning on an antenna repair or replacement as the weather warms up, make sure you use stainless connectors throughout.


2 comments:

  1. Where do you get these stainless connectors? I also use a lot of these automotive connectors and I'm shure most radioamateurs do. But indeed they are not the best. I usually cover them with a thick layer of vulcanizing tape or silicone kit. Most of the time I use stainless bolts and screws and try to protect the connectors with a stainless ring on both sides. So far all can last for years....if you're lucky :). 73, Bas

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    1. Hi Bas,

      I can't remember where I got mine from, but these people are one, albeit UK, supplier: https://www.cablecraft.co.uk/connect/high-performance-cable-lugs/stainless-steel-terminals.html

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