Category Archives: Antenna tuner

20m End fed half wave

I used a 20M EFHW and few years back with varying degrees of success. It was about the time when ‘squid poles’ became a popular antenna supports. The single core wire element was wrapped round the pole but the problem was that most poles then were made of a carbon fibre material which made them conductive. The antenna did not work so well.

This week I tried out a new, 10M fibreglass pole and, like before, wrapped the wire round to the pole. First indications are good with low SWR using a commercial 49:1 balun. This was much better than using the small EFHW tuner I made some years back.

Another idea is to use an off centre loading coil to make it a multiband antenna. More to come, watch this space.

 

Auto antenna tuner kit

There are many different versions of an automatic antenna tuner on ebay and other sites. Some come with a case while others are supplied as a PCB and a bag of parts. There are few instructions around but there are circuits diagrams, or schematics, on some sites.

The board as received

The insulated rear panel

I ordered what I thought was a complete PCB with case but what arrived was a populated board without a case. I complained that it was different to the photo for the item and accepted a partial refund which amounted  nearly what I paid. I then ordered the case for under £13 post-paid.

The board came with SMA sockets already attached which meant it would not fit in the case, so they were removed. Assembly was a bit fiddley, but all seemed to go well. The first power up showed the screen was working. Next came an RF test which did not work. Some quick tests showed that the rear panel had no earth connections to the PL259 sockets!

I decided to make a new panel from aluminium. After reassembling the case and testing with a TX connected to my long wire antenna  everything worked as it should.

I now have an fully automatic ATU that senses when there is a band change and retunes.

The new aluminium panel ready for testing