'My Antenna - the evolution to an effective vertical'


This section tells about the 'up and down' story about my antenna.
I say up and down because due to problems it spent more time going up and down , rather than just staying up.

Now after a few years of working at it I now have  a very effective mono band vertical that allows me to QRP DX the world with relative ease.







The antenna I first installed at this location in 2009 was a commercially made 4 band trapped vertical.
Its construction and design looked sound , but it wasn't without its problems , in fact , it never worked right.

After assembly I checked out the antenna's quoted SWR figures , they were way off.
They were WAYYYY off , even though the antenna was assembled exactly to the dimensions given in the instructions and a good ground plane was provided.
I played around with adjusting the various lengths of the element , but no combination was found that allowed operation on the 4 bands.
The first section that separates 10 and 15 meters had to be collapsed over 30cm shorter than its specified length before it looked anywhere right.
Between 15 and 20 that too had to be set considerably shorter than normal , the 20 and 40 meter sections, well , it didn't seem to make any difference where they were set to.....

On the two bands that sort of worked the efficiency was poor.
I barely could make contacts with 100watts to the UK , a distance of a mere 2,000kms.
I knew performance was poor as with the same power output from the car I had been regularly getting long QSO's with JA and VK , so the land of G's M's and 2's was just not good enough.

The other two bands were unusable.


So down the antenna came for inspection and to recheck that I had done everything right.
I must say at this time that this installation is very high and while its not really windy in Helsinki , the antenna becomes very much of a handful to hold at the base with 7 meters of it swaying around at top.

While I use a safety harness and rope , the idea of slipping off the roof heading down 6 stories is not a pleasant thought , even with string attached.





After it was down I noticed that considerable water had collected in the base.
I had sealed the tube connections with silicone , so this must have been from condensation.
It should drain out anyway as the tube at the bottom is not sealed tightly on the plastic base , , but it doesn't.

So I added a drain hole in the plastic base.
That worked a little , but water still collected on top of the coax connector.

So I drilled a hole on the edge of the connector.

Each time , the antenna going up and down.

Still seeing bad SWR figures (backed up by pathetic performance) I contacted the manufacturer.
They suggested two possibilities , first - that the feed-point was too far away from the radial network , and second , that the radials network wasn't substantial enough.

In my view it was true that the base was a bit too too high , but this was in my case restricted by the coax feeding in from below.

So bringing the antenna down again , I made the mod as shown below.





This allowed the base to come down a few more centimeters.
I also went with the N connector at this time for better cable sealing properties.








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