40/80 vertical dipole antenna feedback 2

The short 40/80 meter top and bottom loaded vertical dipole fed with one single feed line is finally up, but the bottom loading wire for 80 meters is to be replaced with real antenna wire which will be recycled from the existing single band 80 meter T-cap antenna. Nothing went according to the plan laid out for Saturday. First it rained, next it was windy, but the rain was the real show stopper. Negotiating wet grass and wet bamboo stalks across a dry river bed are not my idea of ham radio fun on a Saturday. So like the shuttle, take off was rescheduled for the next 24 hours.

The self resonant frequencies on 40 and 80 were in band for starters, so I was not far off with my assumptions. The feed line is not the real length but should be close by about 4%, pretty significant but workable. The local signal reports indicate that I am not as strong as before, and I expect that, since both the vertical and horizontal radiation pattern should now be different, and the antenna is not yet tuned and optimized. Receive on 40 and 80 after dark show US ham stations at RS 59 with short wave broadcast stations still in the red well over S9.

It will now be very convenient to change 40/80 bands without having to reach over and throw the B&W 550A coax switch. The most modern of antenna installations use one feed line from shack to an external switch box like this. I now expect to [a] save a bit of bread on high demand, short supply coax cable, [b] reclaim some yard space when the 80 meter T-cap is recycled, [c] improve relationship with the XYL for taking down some the aluminum tubing and wire from the sky over the fence, [d] consider an experimental 160 meter short vertical dipole antenna for the available space.

It is pretty windy today as a tropical wave is just east of the islands. Luckily this latest antenna installation boasts a third rope to guy the top of the vertical, just in case we have strong winds like now. My spring balance fish scale indicate a 9 to 10 lb pull on the antenna ropes with the wind gusts. The 3/8 sisal and nylon ropes are supposed to be more than adequate to handle this stress.

Over the next week or two I will consult with the ambidextrous hams to create a portable 40/80 meter version of this antenna. I already have 2 made up lengths of tubing 17.5-feet long for another antenna project, so when these are joined together we will be good to go on 40/80 with a single coax cable fed dual band loaded vertical dipole antenna. Sounds easy to me, and should not be that difficult to fabricate.

Recently I picked up on this link in a discussion group.

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