QRA JO01OX, WAB TM23, Fists #16909 GQRP #15161 DMR-ID 2342670

There is always time to make a new antenna and this one is another Isotron. The design for this can be found here thanks to Luc, F6BQU.

As you can see it’s a slightly 'different' design! The basic materials include:

  • Two aluminium sheets
  • Plastic tubing - 32mm
  • Wire 2.5mm^2 - approximately 8m
  • 2 3mm nuts and bolts with matching solder tags

Construction started by marking and cutting out the two aluminium disks that form the capacitor. The pattern was drawn on plain paper and stuck to the aluminium sheets using paper glue. The disks were then cut out using an oscillating scroll saw. If you take it slowly you can get a very nice cut that produces an, almost perfect, circle. The same process was used to cut out the centre.

Two, matching 3mm, holes were then drilled in each to take a 3mm nut, bolt, and solder tag. With the aid of a length of masking tape the positions of the two disks and coil of wire were marked out along the length of the pipe. Four small sings of pipe were also cut and then split to form simple clamps to hold the disks in place. It reality it tuned out that they were not needed as there was a good friction fit.

The coil of wire was then added using cable ties to hold it in place. I was expecting a little trouble with the wire unwinding but that was not the case and one cable tie at each end seems more than sufficient to hold everything in place.

The connecting wire for the to plate was. then threaded through and pokes through just below the top place.

The coil and the centre wire were then soldered to the tags and an antenna socket added.

To tune the antenna you really need access to an antenna anaylser. Then it's simply a matter of adding turns or removing turns to obtain a dip where required. In my case I ended up removing two turns. It is best to provide a good earth and tune the antenna where you expect to be using it.

Does it work?

It does within a few minutes of putting the antenna up I managed to work Italy, Germany, and Hungary. It does seem to suffer from noise more than my usual antenna. It's also very odd in that the higher I mount the antenna the more noise I get. At ground level I get no noise and no signals and on top of the garage I get lots of nose and lots of signals.