80 Meter Vertical Update!

K2WH writes "For those of you who read my week old story headlined “Put Up a Homebrew 65 Foot 80 Meter Vertical by Yourself” this is a follow up report on the first trial tests and signal reports.


The guy lines were installed at the 20 and 40-foot levels, eye bolts and turnbuckles are installed at the base of various trees. RG-8 foam coax was run from the shack to the antenna. I installed two groups of ferrite cores over the coax to help eliminate common mode currents on the outside of the coax and drilled the bottom of the antenna vertical aluminum to accept the center conductor of the coax. I drilled the circular radial plate for the coax shield and radial connection points.



The base of my antenna is 2 feet above earth. From this point, I ran (4) radials, sloping from the base of the antenna at a 45° angle to the first available tree and then at the 10-foot level from that point on. Since my property lines do not allow a full 65-foot run in some directions, I had to run the radials in various directions to stay on the property.



When completed, I connected my MFJ antenna analyzer and found the following frequencies that exhibited a 1.5:1 SWR or less. 3.7545, 10.200, 14.165, 18.131, 21.250, 28.375, 52.275 and others all the way into the higher VHF frequencies. Simply amazing! Without the analyzer I probably would never have known this. A priceless instrument indeed.



Connecting the coax to my ICOM-756pro ANT 2 connector, I happily found the internal tuner easily tuned the following bands. 80 meters, 30 meters, 20 meters, 17 meters, 12 meters, 10 meters and 6 meters. In addition, I had intentions of putting up a homebrew 6-meter antenna – not anymore. The 756pro internal tuner will not tune the 160 and 40 meter bands. An external unit will probably handle 40 meters but I doubt it will handle 160 meters because the antenna is too short.



The bandwidth at 80 meters was measured at 200khz at a 2:1 SWR or less. The higher bands had correspondingly broader bandwidth. On 6 meters the bandwidth was about 500khz without retuning. All of these tests were run using 100 watts or less.



Initial on the air tests were somewhat inconsistent. For comparison purposes I measure received signal strength on the vertical against my 160-meter dipole. I could rapidly switch from ANT 1 to ANT 2 and make visual "S" meter comparisons. My initial intent for building the vertical was to achieve a low angle of radiation and therefore improve not only my reception of low angle radiation but also transmit a lower angle of radiation. My dipole is not nearly high enough for 160, 80, or 40 for that matter. At the higher frequencies, it is at a sufficient height for low angles of radiation and performs well. This is not to say the 160-meter dipole at 40 feet is a poor performer. On the contrary, I have confirmed 48 states and 20 countries on 160 in about 6 months with the dipole. Therefore, it is no slacker and, it is my only other antenna so, it was the baseline antenna for all other measurements.



As to its receiving performance, it was a mix of better on the vertical or sometimes better on the dipole. It really depends on the incoming wave angle and orientation. The most noticeable differences were on 80 meters (where it was designed); its performance was either equal to or better than the 160-meter dipole. On the higher bands, the dipole was a better performer. Keep in mind I only made a few contacts and the bands were up and down. Better data will be gathered with further testing, and also keep in mind my testing is not what one would call a controlled scientific experiment.



By the way, I fired up the antenna with 1.5kw and it seemed to handle the power OK. I checked for smoking trees in the back yard, and there wasn’t any. There you have it the first update on the antenna. It’s a good performer, probably will be an exceptional one in the upcoming Winter months when band noise subsides. I will be adding more ground radials over the next couple of months and re-check the specs and report again. It should perform better with additional radials but only time will tell. As to the experience, I am satisfied I tried it and am a happy camper. Now if only the lightning would stay away.



K2WH"