K6MM “No-Excuses” 160m Vertical construction notes
Bill Clark, K6WSC 1/1/2018 "I am extremely pleased with the performance of the vertical in the Stew Perry. I have done some points/QSO calculations of the stations reporting on 3830 and found my 5.51 points/QSO is the second highest of the 20 stations surrounding my score. I realize there are several factors involved, but I would like to believe the antenna is the major contributor. Thanks again for a great antenna and writeup." |
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I used a spreadsheet to calculate the specified consistent winding spacing to be used for the entire length of the PVC. My calculations indicated 15.2mm. I used a yard-long measuring stick marked in mm to mark the PVC for each winding. I had a helper for the winding operation. 14AWG stranded wire was used. The 15.2mm spacing was used, with the result that the 258-foot initial wire length was about 5 turns too short to reach the bottom binding bolt. I used a Max-Gain Systems guy ring at the top of the middle PVC section. I notched the top PVC making a place for the wire to transition up to the top PVC thereby allowing room for the guy ring. I used duct tape to secure the wraps during the winding operation every foot or so. Then I used one tube of Liquid Nails Fuze*It and a caulking gun to lay a bead across the windings, spreading the bead out as I went along. The two rings of the capacitance hat are 14AWG bare stranded wire. I bolted the capacitance hat to the top PVC below the elevation of the brass rods. I used bolts instead of actual binding posts to make the connections at the top and bottom of the PVC. I used a DX Engineering base plate with its associated hardware. I also installed a ground rod and made a direct connection to the base plate. I used 2 128-foot radials that bend slightly, and 9 64-foot straight radials. The radials cover about 230 degrees. I have an extensive ground system in the existing antenna farm that may contribute to the radial field. I connected the vertical to my remote antenna switch. Then I used my MFJ-259B in the shack to attempt to tune the vertical. I could find no SWR dips anywhere near 1.8 MHz. In fact, I found a great dip at about 5.3 MHz. I was really puzzled. I noticed the my MFJ-259B only tunes down to 1.765 MHz and thought maybe there would be resonance below that. I started more or less at random trying shorter and longer wire lengths at the base of the vertical using wire nuts for temporary connections. Things were not going well at all around 160m. Then I noticed I was changing the dip at 5.3. I then realized I might be measuring a third harmonic at 5.3, which would put the fundamental below what I could measure with the MFJ. I took out some wire and found a 2.8 SWR dip at 1.830. Wow! My mood instantly went through a 180-degree phase change. I decided to accept the 2.8 dip and have not yet attempted to further tune the vertical. The wraps at the base of the vertical are touching each other. The internal “antenna tuner” in my TS-590SG is quite happy with the vertical from 1.800 to 1.870 MHz. |