HamUniverse used to exist and have a great link showing ideal lengths for end-fed random (non-resonant) wire antennas.
See all the explanation and evolution on the archived article, but these are the best lengths (in feet) that I always referenced:
29, 35.5, 41, 58, 71, 84, 107, 119, 148, 203, 347, 407, 423
The HamUniverse article is linked from the random wires page from AB3AP.
When traveling, we set aside a little time to explore and activate some parks. It gives me a reason to leave the house and see other places.
We stayed a night on Otsego Lake in Cooperstown, NY, so I had easy access to Hyde Hall (US-10044) in Glimmerglass State Park (US-2062), a 2-fer!
My picnic table outside the house was closer to the nearby tree than I usually like, so I deployed the 41-foot (12.5M) EFRW. Within about an hour, I only had 3 FT8 contacts. The bands seemed sort of quiet: I’d only see about 3 signals per cycle on 17M.
I figured it was a good time to compare antennas, so I setup the telescoping whip with the sliding coil. Immediately, that antenna showed me about 12 (4x) signals per cycle. I completed my 10 contacts for the activation with the new antenna and packed up, since we had to get the rest of the way to Vermont.
I checked PSK Reporter when I later got better internet access, and I was being heard, but I wasn’t hearing others. That EFRW was tuning just fine, but not hearing well. I used to struggle with activations with this 41-foot antenna being my main antenna. I may have been making it harder for myself than necessary when I started with the EFRW. The EFHW is pretty convenient enough, so I often use that these days.
I’ve been curious about the T2LT “flower pot” antenna for a while. It’s fed from the bottom and attached to a sturdy PVC pole. I can easily hoist it into a tree, and it has a low wind load, so it could go on top of a flag pole again.
I built it at the SPARC Elmer night from some 75-ohm TV cable I had laying around. I taped and cable-tied it to a thin bit of PVC, and I adapted the feed point from 75ohm TV cable connector to SMA. I had built it long to allow tuning, but it tested to be just about right for 146MHz when I put the VNA on it.
I brought down the Slim Jim with its existing halyard that’s slung over a branch in the front tree. I used that halyard to pull a throw weight and pulley on a new line into the same spot. I dropped the pulley straight down from high spot in the tree, and pulled the halyard out completely. I ran halyard line through the new pulley and hoisted it back up into the tree. Now the Slim Jim hangs free instead of tangled up through the tree.
The Slim Jim in the tree wasn’t working, so my APRS radio had gone quiet. I started testing with the nanoVNA before going out in the cold to check the connections. I found the lead inside was not passing any signal. The connector at the radio was pulling off the cable, so I could push it back together and re-crimp it. I got away with the easy fix.
