Introduction: Stub Tuning a CB Big Stick Antenna for 10 Meters - Ham Radio
Many long years ago, when I was just a pup, I purchased a Shakespeare 'Big Stick' CB antenna. You've seen them – they look like an eighteen foot long, white fiberglass fishing rod. Because of its long, skinny design, the antenna would fit anywhere, on the chimney, up a mast, or shoved among the branches of a tree. Eventually, I got tired of looking at it up my tree, so I took it down and stowed it in the garage, for over twenty years.
Step 1: First Step - Just Try It Out
I had always heard that a Big Stick was wide banded, so I tried it on the10 meter Ham band – just a gnat's whisker from the 11 meter Citizens' Band. Not that wide banded, it turned out.
Nevertheless, with the help of a small antenna matcher I had, I was able to get my rig to work with the antenna. I didn't like the setup, though; I was using a single band, 25 watt amateur band mobile rig and wanted to run the coax straight to the antenna without a lot of hoopla. So I thought and thought and tried something else.
Step 2: Idea
Without going into a lot of technical talk, I knew that either an open or shorted section of coax cable could be used to match an antenna to a transmitter. That seemed a good way to do it. That way, the rig would be connected to the antenna with nothing to tune between the two.
Step 3: Aaa
I assembled my materials: a coaxial “T” fitting, a roll of electrical tape, and a handful of coaxial (RG-58) jumpers of various lengths I already had. The antenna was already mounted, on a piece of 1 ½” mast I had driven into the ground. (It wasn't very long, so the bottom of the antenna was only about a foot off the ground. I didn't know if I needed radials or not, but assuming much of the signal might be headed into the dirt, I installed four of them, about 24' long, buried just below the surface of the ground.). The water table isn't very deep where I live, so the mast made a nice ground connection.
I connected the male end of the “T” fitting to the bottom of the antenna, the end of my antenna cable to one of the two female ends, and attached a 4' jumper to the other one. I was tickled to see that it did bring down the SWR to a lower level than before. I tried a 3' piece and found it better. Then I tried a 2' long jumper (remember, the jumpers are open on the other end) and the SWR was practically perfect at 28.450 MHz – right where I wanted it. I swapped out the jumper for a piece of coax the same length with no connector on the end. I taped up the open end, taped it to the antenna cable, checked my SWR again, and fired her up!
My first contact was a station in Cuba. Following that: Texas, Aruba, Puerto Rico, and the Netherlands Antilles. Did I mention I was running 25 watts SSB? Or that the band conditions were never above poor? Or that my QTH is Maryland?
There's my Instructable; it worked for me. It might work for you. If you have any desire to try it, it might be best to use RG-8 cable, or at the least, RG-8X. I would also be very leery of running much power – I suspect that the tag end of the stub might generate a considerable amount of voltage with a lot of input. Start with more than two feet of cable (maybe 4-6 feet – whatever you have) and snip it off in segments as you go. Keep the braid and center conductor apart; a shorted stub has totally different characteristics.
Frankly, I haven't had the need to mess with it. Communicating over 1800 miles while running the same power as my cell phone charger draws seems good enough to me!
(BTW, this photo isn't current, but I didn''t think that a picture of a Realistic 10-meter rig would be very impressive.)