I bought this used Hy-gain 18AVT 5-band (80/40/20/15/10m) vertical in the mid 80’s. I mounted it 12” off the ground in California, it sort of worked but I was NOT impressed with few DX contacts. Now with +40yrs of HAM’ing, all the internet articles, and QSO’s that continue to tout HF verticals being the theoretical best antenna for DX it was time to resurrect my moth-ball from the rafters. Here is what I did to restore my 18AVT, making it one of my NEW FAVORITE HF antennas at my Ohio country home.
First, I refurbished the antenna making all joints shine, again. Applied liberal amounts of Penetrox to all joints, replaced all clamps with stainless steel clamps, made new top hat radials (using copper coated steel brazing rods – bird strong), cleaned up the 80m coil and re-hot glued it back together. I replaced the old stinger cut for 3925 with a new stinger cut/tuned for 3800 (what a hassle that was to buy from MFJ/Hy-gain). Course adjusted all traps to cover “my” SSB selected centers; 28,500, 21,275, 14,220, 7,180, & 3,800. Mounted and re-tuned all traps starting at 10m working down to get a 1:1 on all selected centers using a MFJ-269. It’s a lot of up-down work (why I use wing nuts on the U mounts) but worth the time. I use nylon guy rope for added stability due to serious open county Ohio winds.)
I dislike ground radials due to all the required work to install properly; so here is where I was going to experiment. I mounted the AVT to the fence post of our new chain-link fence. (Recently we installed a fenced area behind our house-garage to allow our Jack Russell Terriers free but controlled roaming then installed doggy doors to the area. One of my better home improvements that ‘bought’ me favorable accolades from my XYL!) The 5’ chain-link fence is mounted at 4’ height (burying one foot into the ground for anti-dog dig-out). The near house section is 18’ long (up to the side gate) where the AVT is mounted.
I’ve read about the attributes of the Ugly-Balun, here was my opportunity to test it.
My Ubalun is made on 4” PVC with 26 wraps of RG-8x (~30‘ of wrap), used hot glue at the holes and electrical tape on the ends – easy. Bent up some mounts and attached it to the fence – high enough to insure the lawn tractor misses it too. The fence has an added bonus of providing a nice off ground coax run to the house.
The Ugly-Balun really made my vertical a performer. I now got into EU, Med, Africa, and Asia (as well as all points North America). This vertical NOW impressed me and was living up to vertical DX claims. Using my IC-746P and MFJ-989c I was making solid DX contacts even during flaky band conditions. I only need to use the tuner for 75m outside 3725-3875 and the extreme edges of 40m SSB due to >2.5:1. The recheck of my ATV center frequencies showed all to be 1:1.
But I was still not happy with the 18AVT as it is only five bands (80/40/20/15/10m), my favorite day time band is 17m.
On the internet I’d come across articles on how to “add-a-band” to a vertical. These articles were so oblivious and easy to do, I had to try. I made the brackets (adding my own touches to improve mechanical strength).
I only use this string-pulley to tune in the quarter wave 17m (starting at 13.5’) element length and pruning it down to get 1:1 VSWR @ 18.135 MHz. I replaced this string with a SS spring between the PVC and egg insulator, adjusting the PVC mount position to apply only moderate spring tension. Once again, I rechecked all other bands for 1:1 VSWR at my selected center frequencies and found no affects or adjustments needed.
In theory, the actual element connection point is at the aluminum hole in the ‘L’, but I ran the stranded copper 14AWG Radio Shack antenna wire (with soldered eye-lug) to the mounting clamp to insure conductivity and minimize oxidation impacts. The hole may need to be readdressed (with a fixed bolt/nut) if I find friction wear after this winter to the 17m wire element at the hole.
Here is my restored 18AVT SIX band vertical with Ugly-Balun fence mounted.