Published: Thu 07 September 2023
By Dr. Gerg
In Ham Radio .
tags: projects radio ham radio electronics
Four antennas and 3 guy lines. Yes!
Two Antennas Are Simply Not Enough
Ham radio is a hobby. It can be much more than that, but it goes well with a large dish of experimentation and learning. That's the biggest appeal to me.
I knew when I made the leap back into ham radio that this time I was going to go for all the gusto I could get. I still haven't taken the General exam, but it's coming up quick and I plan to keep doing it until I succeed.
2-meter and 440 are really useful bands and FM is a wonderful mode, but that's just the tip of the iceberg. While the HF bands are much more finicky, they are a lot of fun, and so I knew I was going to have to do some extra work to support working the lower VHF and HF bands. That meant antenna work. At this point, I have no plan to invest thousands of dollars in a full-blown tower. So I designed a system I could be happy with that I could afford.
This is where we left off, two antennas.One vertical 2m/440, and one inverted V wire.
In the first go-round , I had put up seventeen feet of chainlink fence toprail. It's an inch and three-eights in diameter and pretty sturdy stuff. That gave me thirty feet of elevation to the bottom of the vertical antenna. The wire antenna provided a touch of guying, and due to the light weight and very small cross section of the vertical antenna, it stood very straight in the wind. I knew that adding any more weight or surface area would require actual guy lines, so I ordered some non-metallic guy rope from DX Engineering.
I constructed my UnUn and purchased a cheap second-hand scanner antenna locally. I was ready for Phase II.
I took a week off work so I could really focus on a bunch of things I'd been toying with. The antenna work was right at the top of the list. I built the mount for the experimental antenna, and figured out how I would prevent the guy lines from slipping down the pole. I know you can buy rings made for that purpose, but that was overkill in this application. In the end, I split a piece of 2-inch PVC in half making two half-moon sections. I used a hose clamp to affix them to the pole, and they are perfect. The guy line may slip down some (probably not), but they can't slip past this stop.
There are three guy lines creating what is nearly an equalateral triangluar pyramid. I was fortunate in that, by affixing the guy lines at the top of my pole, the guys could reach the far eaves of the house without contacting the roofing shingles. That was a serendipity and one that I was happy to accept. Lowering and re-raising the pole is still easy. I just have to go around to six points and loosen the lines holding tension on the wires or the guys themselves.
I terminated the RG8X I'm using for the experimental antenna, added the third run of KMR 400 coax and a couple of lightening arrestors for those.
I pulled the new coax through my attic . I have installed there a 3-inch conduit that runs from the entry point to a point above the ceiling of my office where my gear is located. A length of mule-line is left in that conduit to facilitate adding new cables at any time. Once there, the cable passes through a nice cable nose plate mounted to a single-gang cut-in ring in the ceiling. That is sealed up nicely by some foam rubber pushed into the crevices.
After I got the pole back vertical, I felt unhappy with the location of my experimental antenna. So the next day I moved it up even with the original vertical. I know there will be interaction between the two, but I want to experiment with measuring that just for fun.
Here are the pics (with captions) that are supposed to be worth a thousand words each. Your mileage may vary.
The Antenna Saga Gallery Saga:
From an antenna hardware perspective, I'm good with my setup. There's some tuning on the new end-fed wire to do with the NanoVNA, and the experimental antenna will get experimented with. That's all part of the fun. I'm satisfied, but we all know that will change.
For the foreseeable future I have access to plenty of unknowns to make known. And that's a Thing That Works .
