When we started building the CCD we used a design out of an old 73 magazine. There was a formula to figure out how to make one for whatever band you’d like. It was very specific and only one band at a time could be built.
Then my buddy Charlie, AD7MD came along and researched everything ever printed about them as well as digging into the theory of them. He proceeded to create an all new design that worked on 2 bands and actually had a flatter SWR than the original designs.
If you decide to build your own please understand that we can’t possibly be responsible for errors or solder connections or if it just simply doesn’t work well for you. When we built them it was under manufacturing standards and each antenna was less than an inch different from the next…probably less.
All measurements are from center to center except for the end insulators. So, from the center of the balun to the center of the board, and from board to board, these numbers are center to center. The last section is from center of the board to the end of the wire looped in the end insulator.
And for those familiar with dipoles and how you adjust them by trimming the ends…DO NOT DO THAT on the CCD. It will mess up the other band in ways you won’t like. This is a delicate and tested balance not to be poked with. (grin)
The WIRE used should be 14 gauge and not coated. And the balun is a W2AU 4:1 balun. Nothing special about the end insulators, anything will work. If you need the balun we actually still have plenty of those. Just go to the ‘order’ page.
20 meter version
Sections are 35″ and the total size is 70ft
Qty: 22 – 100pf 5% silver mica 500volt capacitor
20/40 meter version (my favorite)
Sections are 57″ and the total size is 114ft
Qty: 22 – 270pf 5% silver mica 500volt capacitor
40/80 meter version
Sections are 92″ and the total size is 230ft
Qty: 28 – 500pf 5% silver mica 500volt capacitor
There is a bit of an unexplained quirk in the 20/40 antennas in that they seem to have a raised SWR if mounted between 20 and 30 feet in the air. Higher or lower seems to work best.
These antennas are rated at about 800 watts on SSB and shorter burst data modes, and for CW and long transmission data we suggest about 300 watts. Don’t get kV versions of the caps and think that’ll give you full power capability. On paper the antennas should handle twice the legal limit. BUT, there is an internal resistance in the capacitors and they will heat up and pop if you run to much power. You’ve been warned.
Feel free to email me if you have any questions. Take your time and think it through and you should be fine.
Some images of how we built them.
The above images shows the JIG I had to make sure each section was an exact length. The boards were designed to fit in the slot and allow soldering. I always cut the wire to exact length and inserted them into the boards and bent them before soldering. The wicking around the bend in the wire made the connection super strong physically and electrically.