Stub Tuning a CB Big Stick Antenna for 10 Meters - Ham Radio


Introduction: Stub Tuning a CB Big Stick Antenna for 10 Meters - Ham Radio

About: When I was a boy, I was amazed how my grandfather could make flotsam and jetsam into useful things. I am proud that I have inherited some of his skill.

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.

Step 4:

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!


Step 5:

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?

Step 6:

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.)



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    I made a "Moxon" 11 meter antenna (CB) since I have yet to take the test to get my technician license. The Moxon is basically a folded vertical 1/4 wave dipole with a slightly longer reflective folded element. It has pretty good gain and I have it mounted on a tv rotor above the roof.I did the same thing you did to bring it into resonance in the middle of the band.I just used a small length of wire clipped to the bottom of both elements.

    Would this method work if you put the stub at the back of the radio as opposed to the base of the antenna? It would be much more convenient to do it that way, as opposed to climbing up and down on the roof of the house. I have the ability to put an antenna on the eve of the house but it's a two story house with a pretty steep pitch so climbing up and down to adjust or cut the coax to match the radio to the antenna is pretty tricky. Can I do this at the back of the radio?

    Why not just cut the top section? Trial and error but maybe start with 5 or 6" and work from there. Should be able to dial it in.

    4 replies

    The bottom half of the antenna is part of the dipole - if you cut off the top, it gets more and more unbalanced. You can't get much easier than my method of experimenting with different length coax jumpers.

    Ok. So the big stick is a coaxial dipole. I use an A-99 for 10 meters which is not that type so cutting the top a few inches dials it right in for 10.

    That's correct. The Big Stick is supposed to be broad banded but it isn't that broad. Also, there are a few different varieties. Mine is 30-some years old, if I count correctly.

    In 1975 I purchased a Shakesphere "Big Stik" antenna for my (get this) a Cobra 85 base/mobile radio. Back in the day, we had a guy locally that would install a chrystal bar and make the radio not only from 23 channels, but 40 channels, and the radio had the capability of going 40 channels below channel 1 and 40 channels above 40 and to add a little spice, the radio had the capability of the "inbetweens". If you look at the frequencys listing you'll notice that there's a 20 Mhz jump between I think channel 4 and channel 5. I had the capability to go to those frequencies as well. He "peaked" the output of the radio to about 30 watts or a little more with a 1:1 SWR reading. I installed an Astatic D-104 lollipop mic as well. I loved that old radio. As a sideshow, I borrowed an amp from my neighbor capabile of 500 watts. Of course I had to have the radio tuned back to 4 watts. One night while DX'ing to Italy, I burned out the big stik. I was sad, but very happy with the performance of the antenna, Needless to say, I gave back the amp, had the radio tuned back up to 30 watts or so, and bought a "Starduster", Needless to say, neighbors were banging on the door cause I would blank out their TV screens. What I didn't know, my neighbor across the streets wife was a nurse, so she would record the soaps on her VCR so she could watch in the evening They got very angry with me because I would come home in the afternoon working early mornings and shooting skip and stepping on the shows she was recording. I don't know where this story is going, but anyway, thanks for your input on the antenna tuning idea. I'm in the process of setting up another base station here at the house, but fortunately for my neighbors, I moved 3500 miles away. Something tells me I won't have a problem splashing their VCR anymore. LOL Anyway, contact me, I'd love to chat with you. THanks "Baggy Pants of Southern California. 73's

    Anybody up to speed on an amp instructable?

    Good day RangerJ

    I did a slightly modified version of your stub tune on a mobile CB/10 Meter transceiver. Being a mobile station I could not run a lot of stub at the splitter. One foot of coaxial cable was not enough and I did not want to run more so I put an old fashion terminating resistor for networks at the end of the one foot coaxial cable. The antenna is a Wilson Silverload tunable antenna with the extra ground plane cable at the threaded end of the antenna. Grounding the ground plane cable made the CB band near perfect for Standing Wave. 10 meter was terrible though. The standing wave ratio was 5 to 1 with or without the ground plane cable grounded. I had to place the splitter at the radio end of the coaxial cable. So it is directly on the back of the radio. The standing wave ratio is very close to 1 to 1 in all CB channels. The 10 meter band never gets a standing wave ratio higher than 1.8 to 1. All the way to just under 30 Megahertz the standing wave never gets above 1.8 now. I am not sure how much power I am losing through this configuration yet but the radio has absolutely no danger to it at all. I know the 50 Ohm terminating resistor on the 1 foot coaxial may be acting like a dummy load. My effective transmitted power may be very low. I am not sure yet because the salvaged watt meter does not work. Heck the radio is a dumpster dive I repaired myself too. Your thoughts on the 50 ohm terminating resistor at the end of the 1 foot coaxial at the radio end is very welcome. Thank you for your idea and for your future advice on my modified configuration of your idea.

    1 reply

    I think the terminating resistor is
    soaking up some of the power, for sure. But that's the same case with
    the stub or even a transmatch. The point is to trick the radio into
    thinking the feedline/antenna combination is a perfect match. I used to
    have an old transmitter with a big swamping resistor inside - some
    signal went into the antenna and the rest into the resistor, more or
    less depending on the antenna.

    I guess the real test is how well it works.

    Thanks for the comment.

    Back in the 70's I put a 7ft FireStik on this, instead of the 102in Whip. Now your Talking! It will also give you a perfect match!!

    Great instructable. The key is the matching transformer. Wish i could find the info for making that universal balm transformer that automatically matched your antenns to your reciever.

    1 reply

    Thanks -
    If you find that universal balun schematic, I would love to see it. Hook that to some lossless coax and you would be uptown!