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Ready for a fun day in the shop building a new HF antenna?
Note: You can buy these complete and ready to
put up at our store! You don't have to build
it if you'd rather not.
There have been dozens of suggested ways to build this type of
antenna. The problem is, you're creating a basic dipole but every meter
or so you have to have a way to install a capacitor in series with the
wire. In each antenna there are usually over 22-32 of
these so finding a quick and lasting method of doing this is easily the most
challenging part of making this antenna.
| "A nice benefit, there was a noticible
decrease in ambient noise level on the CCD. -
Jon, KC5LVW" |
I've found, because capacitors only come in certain standard
values, it is better to select the standard valued capacitor and calculate the
antenna design from that. Try various sizes based on the standards and
try different frequencies and get a feel for what it takes. Any number of
caps between 22
and 32 are just fine.
More than 32 doesn't make any
difference in the characteristics of the antenna.
The law of diminishing returns.
The calculator below will tell you how to build a CCD
based on the cap size you want to use and what frequency you want it to
resonate on. Note that it must be an even number of caps in the
results...can't build a dipole style antenna with an odd number. However,
if you are wanting to build a long wire version an odd number is fine.
This would be a single band antenna!
Calculate your CCD...
Number of Caps =
0
Number of wire sections =
0
Length of Sections =
0
Total antenna length =
0
inches or
0
feet
Here's how I build these antennas.
First, the boards themselves have gone through a
couple versions. The current one is shown below. I added an
extra set of holes for the two standard sizes of caps. I also widened
the pads to give more strength.
Above you can see a board with slots cut into it.
I used a Dummel tool with a narrow rounter bit installed. These are
the end slots on the left of the jig. Since I make various versions I
have each slot measured out from the single assembly slot on the right end
of the jig.
This is the right end of the jig. All
connections are made here. You can see how the boards fit into the
slots. I line up the wire so that, where I cut it, it would have
enough room to go into the holes.
I then pull them into the holes and bend them as they
will be in the finished antenna. It's important to use 14 gauge
stranded wire with these boards. The wire fits exactly right through
the holes and even without soldering the edge of the boards cut into the
wire and make a solid physical connection. Of course, soldering is
needed.
I hold the board down with the dykes as I solder the
two wires. I make sure the holes are completely filled all the way
around reducing the possibility of corrosion from weather. I use a 140
watt gun and get the board and wire more than hot enough to let the solder
flow smoothly around everything.
I also leave 10-15 seconds for everything to cool
enough to not cause a cold solder joint. The connection is inspected
under a magnifier lamp and re-done if not 100% perfect.
Here's another look at the left side of the jig.
As each board is completed it's placed in the slot on the left side and held
in place. (I use this hammer) I can then pull tight between it and the
right end and make my next cut exactly the right length. This gives me
perfect lengths every time.
As the antenna takes shape I use two nails to wrap it
on. Even though the wire is kink free a CCD with boards can get VERY
tangled up. Have some zip ties around to keep things tied up well
until you are ready to take it out and put it up.
When putting it up be sure to hold each side of the
antenna in one hand and let out each wire/cap section at a time. If
you loose control of the unspooling you'll spend a LOT of time getting it
untangled.
There you have it. Between the boards and the
method above, we come out with perfect CCD wire lengths.
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