Antenna Overhaul

Having tried virtually everything to make the existing setup work I’ve done some digging into the possible issues and decided to change the wire I’m using. Up until now I’ve been using what I thought was solid copper speaker wire, but as it turns out it’s in fact copper coated, so I’ve decided to change to 2.5mm2 singles.

As well as changing the wire I’m also using adhesive lined heat shrink crimp connectors and liquid electric tape to waterproof the connectors as much as possible. The first image was me testing the connector on some of my old cable, you can see the glue of the adhesive lining in the image. The second image is the final product with the liquid electric tape.

Previously the 40m legs ran down from the balun to the corners of the roof and then around the gutter clipped on, with the 20m legs they ran to the centre point between the pole/balun and the corner of the roof then along the gutter (to keep the 20m and 40m legs separated).

This time as I replaced the legs of the dipole I decided to run the 40m legs over the roof, partly as it was easier than clipping all the way around, but also to keep it raised a little more, this also meant that I could run the 20m legs directly to the corners of the house.

One issue I found with running the 40m legs over the roof rather than round the gutter was that it was very close to the roof tiles, thus causing SWR changes in the wet, to combat this I used a ring camera solar panel mount to raise it a little above the gutter level, not ideal but doing the job for the time being.

I have been really happy with the outcome of the work and have had some great DX on FT8 as well as some less impressive DX on CW and SSB. On FT8 I managed my first Australia, Indonesia, Saudi Arabia and Uruguay contacts amongst others, and on SSB my first USA contact.

I know that propagation has a lot more to do with these contacts than the antenna, but nonetheless I am very happy with the performance so far, I am just hoping that it lasts longer than previous attempts!

Antenna Inspection

Once again, almost like clockwork, my antenna started exhibiting issues a year on from being overhauled. Despite my efforts using epoxy resin in the crimp connectors to make them watertight, the legs of the fan dipole have started to deteriorate at the crimp, however inspecting it wasn’t as simple as I’d hoped.

My first issue on inspecting this was that the pulley rope had almost completely disintegrated, once I discovered this I didn’t want to leave it as it was and felt that I needed to replace it immediately, but it turned out that was a bit of a nightmare to replace.

My first effort was to use a brick line to attach the new rope to the old rope, that was a mistake! The brick line being so thin slid down the side of the pulley and took a lot of work with electricians rods and a loft opening pole to get it back on, once back on I was able to run the new rope across. Another issue I came across was that the pulley has seized in place, not a huge issue but not ideal and wont do the rope any favours, however I’ll deal with that another day!

In a typical manner I ended up spending the day sorting an issue which I wasn’t even aware existed until I started looking at something else, other than seeing that the wire in the crimps had deteriorated I didn’t get the chance to fix anything, that is to follow.

Back On The Air

I’m now thankfully back on the air, I attached the wire to the new potted N-type balun using ring crimp connectors, but this time rather than Silkaflex or solder I’ve used some Araldite in the connectors and self amalgamating tape around them to try to avoid water and air getting to the connection. I’m not sure that this will work any better but worth a try, I may need to source some new wire with less of a tendency to corrode for next time.

I also took the opportunity to slacken the wire to get the balun as high as possible before clipping it back on to the gutter. I fold the ends so can afford to lose a little bit when I add new connectors, but it does get more difficult each time…

I’ve checked the SWR readout and am happy with what I see.

Antenna Issues Part 2

So I’ve had a little investigation into my antenna issues, I brought the antenna down on the winch took a look. It looks like the tape over the crimp connectors has reacted with the Sikaflex in some way so water may well have got in there. I stripped off the Sikaflex (which I wont use again because removing it is a sticky nightmare) and put Araldite over the cracks. After winching the antenna back up I checked the SWR trace again and it had got even worse, which was similar to my experience last year.

Looking at the balun there are a fair few cracks which I’ve temporarily protected with Araldite, it’s also not potted and uses a SO-239 so I’ve chosen to replace it with a potted balun which uses an N-type connector which are what I use elsewhere in my shack and what I’ve got on the end of my coax, this allows me to remove the N-type to PL-259 adapter.

Antenna Issues

Unfortunately for the third year running at almost exactly the same time of year my antenna has stopped working. I noticed that the ATU was struggling to get the SWR down to where I would expect so I connected up my NanoVNA and noticed a bizarre trace.

Blue is the reference from last summer, yellow is the new trace.

Having had a quick look at the antenna it seems to be the same issue, corrosion of the wire that makes the legs of the antenna, I’d used significant quantities of Silkaflex sealant to try to avoid the water getting in so that’s a bit disappointing! After having a think about the issues and a chat with some of the club members it was also suggested that the issue could be water in the balun.

Given that the balun is a bit long in the tooth and already had a small crack protected by gaffa tape I may replace it.

Until I can sort things out I’m now off the air which is very frustrating. Like last year if feels as if it has happened just as I’m getting the hang of CW, last year it was around my first couple of QSOs, this year it’s as I’ve started getting in the swing of a few QSOs each week.

While I’m off the air I’m using my spare time to read Bill Meara’s book SolderSmoke ‘Global Adventures in Wireless Electronics’ it’s a really good read and I might post a bit of a review on it at a later date.