Using the True Ladder Line Doublet for Florida Winter Field Day February 2017
I am a member of BARS (Beaches Amateur Radio Society) here in Jacksonville Beach, Florida. My wife and I are here for the winter. The club holds their own "winter" field day and ours was on Saturday, February 4th. We operated at a shooting range and lodge for the Fraternal Order of Police. A wonderful place with plenty of tall, Florida pines for stringing antennas from.
The club members were a bit curious about 600 ohm open wire-fed doublets so, I brought along a 125', 10-80M one, to setup as my antenna for the day. To make life easier, I decided to simply use it as an inverted V. We got the center support line strung up through the tree with very little trouble. We raised the center insulator up which came to about 50' or so. The ends of the doublet were easily tied off to an old, 4x4 post and a small tree.
We unwound the 100' of feedline and started to run that out, just long enough to reach my tuner, an MFJ-993B, sitting on the table beside my radio. I build the ladderline with spacers that "snap" on every two feet. This way, one can simply count the spacers and multiply by two to come up with the length. Well, our length worked out to be 66' which, is a full wavelength on 20M. No go! We don't want the feed to be an even resonant length on ANY of the bands we want to operate. That's not to say that the tuner wouldn't handle it. I bet it would. The guys that were helping me setup, were now asking, "what are we going to do?" I moved the tuner to another area of the deck we were on and strapped it to the railing using a bungee cord. We counted back several spacers and calculated that we were now at 58 feet. Good enough! I cut the wire, stripped the ends and secured them to a couple of gold-plated banana plugs and plugged them in. I run the tuner off an old 5.5AH Gel Cell in a camera bag with a receptacle to accept a plug. It will run for days and provide me with a "remote" tuner. We powered it up, walked over to the radio, put 5W out to tune and bingo, 1:1 and on the air.
I put my call out briefly and worked two Pennsylvania stations and one Ohio in the first couple of minutes. As the day went on, I worked several friends in Vermont during their VTQSO Party. I was asked to lower power from my 100W to a QRP level. I was wiping out others at our location. I dropped to 10W and then worked a station in Lithuania! Pretty cool!
So, the purpose of this blog is to simply show how easy we can make it work out as well as the fact it's about as simple as you can get. I've worked with many hams all over the world that just want to complicate everything and would rather believe that an open wire fed doublet must be harder than this! That couldn't be further from the truth.
Look at the photos below and you'll get an idea about our setup.
Just my trusty Kenwood TS-570 and the Samlex Switcher power supply.
The MFJ-993B "secured" to the railing.
View of the ladder line going up to the center feedpoint. A beautiful AND efficient sight!
A view to the top.
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