Antenna follies:
I used the recent “Radio in the Park” day to work on an antenna, rather than just make some contacts. The first step was to get a pair of those 5 metre telescoping whips into the sky. The object of the exercise was to make them go from a 20m dipole (which they do easily) into something that would make noise on 40. An additional constraint was that the whole thing should pack into no more than 50 cm, the collapsed length of the mast they will go up on. Since they droop so much when set out horizontally, I figured I should stuff them into a piece of dowel at an up angle of about 20 degrees or so. The angle proved to be about right, with the tips of the whips ending up about at the same height as the threaded ends. Unfortunately the assembly was too heavy for the mast, so I couldn’t raise it enough to proceed with plan “A”, 5m out and 5m of wire straight down from each tip. It also turned out that the end grain of a piece of softwood dowel is not tough enough to hold a 5 metre whip at full extension. Pressing on anyway, I proceeded to attach the 5m length of wire to each of the tips. Of course with the mast being less than 5m tall at this point, the ends of the wire were on the ground. Not so good.
Brilliant idea: tie the free ends of the wire together and make a one wavelength loop. So I tied them up and got a 3:1 SWR. Not bad for a first cut, with the apex of the triangle a foot or two off the ground. MUCH later I figured out it sure isn’t a one wavelength loop, with only 20m of conductor around the perimeter. Does anyone have an idea of what the impedance of this beast should be on 40m? I have a hunch that once it gets up a bit higher, it should play on 20 if the loose ends are tied together, and on 40 if they are free to drop straight down.
So since then, I’ve put in a skinnier hardwood dowel, drilled and tapped some aluminum L brackets to hold the whips and made some blocks to tilt the L brackets. I’m hoping to try again soon with version 2 of the thing. Stay tuned.
Over at RHQ, the race is on to get things squared away on the roof before the start of that other season. One thing we found was that our V/UHF vertical had become waterlogged. We (KMV/FFK) took it down, dried it out and got it back up the next week, now with better waterproofing at the joint. That should hold us until the satellite antennas are finally up there. I was hoping they would be up in time for the June VHF contest, then the September one. Now I will be happy if they go up on time for the January version.
The Flex radio is just about ready for casual use, (meaning a few people have tried it out and it ain’t broke yet), and next up is the Icom. Let me know if you want to come in and play.
Meanwhile there have been a few exams, a little antenna work for some folks, and the nets and meetings that were dormant over the summer are coming back to life. The calendar keeps rolling along.
73
Keep on hamming
mk
Last Updated on 2025-10-01 by Eve