Probably all hams of a certain age have dreamed about an insulated 5/8 wavelength antenna for 40 meters at one time or another.

My version of ON4UN's 83 foot transmit antenna is used at KØFF for 40 meters only, but his article in LOW BAND DXing

The first challenge was to decide on which base insulators to use from the various styles available,

I chose the medium sized High Voltage Buss insulators, shown in various sizes in the above photo.

These were mounted between two 1/4" CRS steel plates that I had designed and built (one is shown in above photo),

A"sandwich" at work. While the compression strength of the assembly is absolutely no problem, the

shear strength was unknown, so slots were engineered into the plates to accept steel pipe spacers held in place with

Three one foot holes for concrete were drilled into the earth with a tractor mounted post-hole digger. Only about 4 feet deep,

into these were inserted large J-bolts then filled with concrete. A form was used to keep the bolts aligned during curing.

Once prepared, a one meter diameter heavy aluminum plate was first installed, rim drilled to accept the 1/4" galvanized radial bolts.

Then on top of the J-bolt is mounted the bottom plate of the sandwich and the rest installed piece by piece. The top plate of

the sandwich holds the Rohn tiltover clamps to which the 56' tower is eventually mounted. Radials are tuned and insulated above ground their whole length, cut for 160, 80 and 40 meters since at the time I had ideas for a multiband vertical.

A Rohn 56' self-supporting tower was selected to use as the main antenna element with aluminum tubing gleened from various previous vertical projects. Out the top of the tower is a short 2" mast to which the top element is clamped using a typical vertical antenna mount.

Because the antenna is mounted near the edge of the bluff, heavy winds were anticipated. To eliminate this as a problem two levels of Dacron rope were used as guys. Guypoints were made from pieces of UNISTRUT and bolted to the tower at the joints using the regular tower bolts supplied by Rohn.

This antenna is one of several I made to use 75 Ohm feedline. The L-C match was worked out with the assistance of K7GCO.

As usual with my antenna installations, grounding and counterpoise are considered separate elements.

Next to the antenna I mounted a telephone pole with a big pulley at the top. With the aid of my trusty tower rope and

It's been up over 15 years now and I must say that I am pleased with the results. No way would I ever use a vertical antenna to receive on, but for transmitting, it is superb. Signal reports have been embarrassing actually. Once during the initial test-out, I was tuning up on SSB, and a stateside ham broke in and said" My gosh! You have the strongest signal I have ever heard on 40M". I went back to him and explained the antenna, and that I was tuning up with ONE WATT!