The shack is still in disarray but there is light at the end of the tunnel. The acorns are raining down like hail, so the leaves are not far behind. It is time to wrap up the shack re-assembly before leaf raking(and contesting!) season arrives in earnest. I need to keep the leaves from carpeting the grass, or else the small amount of grass will be croaked by the carpet of leaves.
The long outstanding antenna switch has been finished. I already had most of the parts ready. The remote switch and inside switch box have been assembled for quite a while. I finished the outside enclosure over the summer. During the last couple of weeks I put connectors on the control cables and ran them from the shack to the location chosen for the switch. One of the first really pretty fall days dropped in on Saturday so final assembly of all of the components got DONE! Sweeeet.
That same beautiful Saturday was perfect for performing maintenance on most of the antennas and their support ropes. Time to adjust the 20m and 40m dipoles. They were both too short, and resonant above the SSB segments. Both are now resonant just above the middle of the CW segments on their bands.
The 15m/10m antenna is a nested rectangular loop. It is the same size or length of wire as a normal quad loop, but instead of square, the vertical sides are just a bit less than 2 times the length of the horizontal sides. It is fed at the bottom(a short side, and closer to the ground) and is thus horizontally polarized. My own antenna differs somewhat from this website description and the original idea goes back at least to K6STI. In my own version, I use a length of aluminum channel as the top horizontal. I’m really happy with this antenna. When the bands open, it works well. Its most endearing characteristic is that it is easily rotatable, as it hangs from a single support. It has tag lines, which are used to rotate and secure the direction.
The rectangle also has the benefits of any quad loop while showing a nice 50 ohm match. Sweet. I had been feeding each loop from a single feedline. Since I’m planning ahead for the use of the band pass filters, it was time to put each on a separate line. Since the antenna needed to be dropped anyway, I also put up a set of fresh ropes.
Each loop required re-pruning after they were separated. Both required about four inches of wire added to bring their resonances down to the CW band segments. They also now show more a broad coverage at less than 2:1 SWR. Using a single feed line is a bit of a trade-off. You trade a bit of bandwidth for the convenience of a single line.
Since they are now using separate feedlines, I could have gone to normal equilateral quad loops, and maybe used a balun or quarter wave matching section. It would have raised the average height above ground. This was a bad idea for my situation given their location, because the increased length of the horizontals would make them more of a snaggle problem with adjacent trees.
I’ve also got the K2 160m module installed, so I’m looking forward to that. Band Pass Filter Fever is on hold until I can scrounge up enough parts.
In a very unusual turn of events, Murphy was off bothering someone else Saturday. 🙂
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