Both ends of the 10' tube section are marked every 60०. These indicate the centers for Dynaflex 230 adhesive strips (6) which will secure the wire windings on the tube. It's available at The Home Depot. Although sold as a window sealant, the all-weather characteristics of the '230 make it ideal for this application. See the manufacturer's web site for usages and safety data; http://www.dap.com/dap-products-ph/dynaflex-230-premium-indooroutdoor-sealant/
Use 3/4 to 1 inch spacing for the sealant strip width. Blue painter's tape is used to set the space. Use your fingers cover the gap with a very thin coating of sealant. Disposable latex gloves come in handy for this job. 
Allow the goop to set up for at least 4 hours before removing the tape. These strips will secure the wire in position by forming small landing pads that stay flexible for a long time. And it's inexpensive.

The new 6" flange is mounted to the original sheave. The 14" tube section on the right will serve as the connector between the head stock and the coil form. It's cut from a junk piece of schedule 80
tube. Normally it would be glued to the flange socket, but not in the case of 6" tubing. 

Both the socket seat and the end insert are coated with automatic transmission fluid. The ATF compound has tremendous film strength, and keeps the insert from seizing in the socket seat for quick disassembly.  Final alignment of the fixture involves using a rubber hammer, so glue is ruled out.

The blue painter's tape shown here defines the channel for the Dab adhesive. Chalk lines are helpful for siting the tape position but are not necessary. The glue is applied by hand for a thin coating along the entire length of the tube. Wait at least three hours before removing the tape. The wire will find a permanent seat on the sealant immediately as winding proceeds. 

The operator's mobile station is in position. The on/off control line is behind the fixture so as not to be run over by the transport wheels. There is no brake on the motor, so rotation will continue for 2 to
3 seconds after the power is turned off. The control switch can be seen just to the left of the wire spool.

The Ugly Balun is attached to the dipole. It's wound with RG6/U.

The 20 footer goes together

Monday, June 26, 2017

The new schedule 40, 4 inch, 20 foot section arrives from Mars Electric.

Getting the piece off the truck and carrying it into my garage, I learn one thing immediately;
it's too big for me to handle.

The first thing to do is to trim it down to 15 feet.

The bell end of the tube is resting on the idler roll in the background. The cut end is in the foreground
and will be fitted with a Cantex 4" coupler, P/N 6141632.

The coupler has perfectly trimmed edges and with the face of the headstock fitting the two edges  form a channel for the headstock support wheels. Now there is no travel of the tube in the fixture.

Next, the A52EA42 will get all taped up in preparation for applying the Dap Dynaflex 230 (clear)
caulking compound. The blue painter's tape is used to make 3/4" channels every 60 degrees of rotation, or 6 channels, on the entire length of the tube. The Dap material goes on white and is spread on the channels with the fingers to form a thin coating.

  When it drys to a clear finish, it's time to peel off the tape.

Four holes are drilled next; two for each half of the dipole. A one inch space is left in the center
for mounting the coaxial cable retaining clamp.

Above, one half of the winding job is complete. The aluminum .062" (1/16") wire goes on smoothly and the Dynaflex 230 holds it in place perfectly. Coiling time for the 82" section is about 3 hours.
The on/off switch is mounted just to the left of the wire spool. There are always frequent starts and stops, and this is a convenient place for the operator. Also notice the glasses on the seat behind the spool. These are 3.5 dioptre in strength, and are necessary to pinpoint the exact location of the wire
and the guide tool.

To end the job, we'll start the second half from the opposite end of the tube, close to the headstock.

Finally, we're done winding, and only the coaxial cable connection remain.

Standing next to the garage, the finished product. The vertical dipole has two coils each 82 inches
long. 779 feet of wire cover each half.

Note !

The XYL's plants must be protected at all costs !

Another approach for wire stability

Today we'll tackle the problem of coil stability in a new way.

Here is a new 10' section of schedule 40 4" Cantex, ready for cleaning. Scotch-Brite and windshield washer fluid are used to remove small surface nicks and dirt.

The two black plastic brackets holding the tube are called base spacers in Cantex-speak, part number
5355969, and are not very expensive. They come in very handy if you do any work with 4" material.

After cleaning, a protractor is attached to the bell end of the tube.

We'll make hash marks every 60 degrees, for a total of six on the circumference.

The protractor is fastened to the other end of the tube, and six more hash marks are drawn. Now we
have two end points for the next step, snapping a chalk line.

Next, we uses blue painter's tape to make a 1/2 inch channel.

Half of the tape is shown here. We remove the chalk line before putting on the second tape border.

With both tape lines in place, we're ready to apply the wire stabilizer. This is a very thin coating of DAP
Dynaflex 230 caulking compound, purchased from the Home Depot. Please read the instructions on the container. This stuff sticks to PVC and is useful over a wide temperature range. You may want to make a practice run first. Try putting down a bead about 1/10 of an inch in diameter.Then use a latex glove or wrap your index finger in plastic wrap and smooth out the caulk manually. The goal is to make a small adhesive pad for the coiled wire. Give the Dynaflex 5 minutes to set up before removing the tape.

The thin caulk line presents a low profile on the tube. Next, we wind the coil.

Another approach to coil stability.

The brake on the wire spool hub is set to hand tight plus three quarters of a complete turn. This yields a very high wire tension on the coil feed wire. The results are a uniform wind and no shift of wire on the form.

It doesn't get better than this. The whole 10 foot tube shows this consistency !
Here is another lathe shot:

This is a picture of the wire spool stand and the tube, at the half way point in construction.

 
And here is the finished antenna;

I fired this coil up on the low end of forty meters and was pleasantly surprised. I found three resonance points on the tuning capacitor on my MFJ antenna turner, and each time I changed frequency slightly on my transceiver, I had to reset the MFJ unit.
The next step will be a twenty footer !!! Must wait for the return of warmer weather.
A quick note to the coil builder. Stay with the Cantex conduit. I had occasion to try to use brand x PVC electrical conduit for a test trial and ran into serious problems;
1. Check for rigidity. The "x" 10 foot section took a bend on the way home in the back of my car. Not good.
2. Try drilling holes for tap positions. I drilled six holes; two were difficult and four went through the material like butter. Not good.
3. Here's the show stopper. The bell end was not sized correctly. It seized on my sheave mandrel and was an absolute nightmare to remove. Really not good.
In fairness to the conduit industry, I must point out that their product(s) are not designed for my applications.

A new vertical antenna.

Today a new 10 footer went up, wound with 1/16 inch aluminum wire. The 5356 alloy winds consistently, as shown below. Winding time was approximately 4 hours. If you try this assembly technique, please remember to use loose-fitting gloves and safety glasses !

The finished vertical antenna has continuous coil of 1025 feet of wire !