Repair of the CB Half-Wave antenna...

Back in November of 2016, I put up a CB half-wave vertical to use on 28 MHz. After being off air for four years, I just wanted to put up something cheap and easy to listen on the 10 metre band. I tuned it for 28.3 MHz and it tuned out to have a reasonable performance.

After being exposed to the weather for over a year, I found that when I tried to use it a few weeks back, it had gone intermittent and the VSWR was really high.

My initial suspicion was that water had got into one of the five telescopic sections that slide into each other resulting in poor contacts. I used a multimeter to measure the resistance between each section when the antenna was on the ground and it measured ok. I removed the waterproofing for the top telescopic section and on inspection, it was as clean as the day I put the antenna up.

One thing I then noticed was that the small screw at the base of the antenna looked slightly rusted. Using a Phillips screwdriver, I tightened this slightly and this fixed the problem! The VSWR returned to a nice low curve as it was before.

In hindsight, I probably should have waterproofed this screw from the elements but I'd guess that most people don't bother. It reminded me of a valuable lesson... be careful where there are two different types of metals touching.

In this case, a steel screw was making contact with aluminium ....a sure recipe for corrosion issues. I'll probably try to waterproof this over the next week.