Antenna Masts

A low cost self supporting 40 foot (12 meter) mast can be made from a common 50 foot (15 meter) telescoping guyed TV mast. This is my double zepp antenna support mast, which I use for my 15 meters modes K and T uplink, a well as on all of the HF bands.

Extend each 10 foot (3 meter) section 5 feet (1.5 meters) and redrill the locking pin holes through both masts to secure them at half mast with a large stainless steel bolt, washer, lockwasher and nut. Mark a dark vertical line where the two masts telescope together so you can see how they should be positioned for the holes to line up. Then you will not have to hunt for the holes later when raising the masts. Use the circular clamp locking bolts that are at the top of each mast section to tighten out the slop between masts. You will end up with a self supporting 30 foot mast. I purchased two more 10 foot (3 meter) mast sections to similarly telescope into the top mast to extend my mast to 40 feet (12 meters).

For a base I dug a post hole and positioned a pipe vertically in the hole that just fit inside the bottom mast section. I filled the hole with concrete, leaving 4 inches (10 cm) of this pipe above the top. The bottom mast section was placed onto this pipe stub and secured with a bolt similar to the upper sections. A sturdy wooden frame was fabricated that was structurally attached to my house about 10 feet (3 meters) above the ground. The top of the first 10 foot (3 meter) mast section was securely clamped to this frame. This brace also provided a convenient point to tie my ladder while raising and lowering my antenna mast, giving me a safe and solid structure to work from.

This self supporting mast whipped (but did not break) more than I liked during a strong wind storm so I added a set of mylar guys near the top to keep it (and my SWR) rock steady. But as guys are not needed normally, I can raise and lower it by myself for antenna maintenance. Stainless steel hose clamps secured to the top of each section will keep each section from going too far inside the lower section when lowered. This is a convenient place to secure your open line stand-offs.

Guy wires are often a problem, as metal ones need ugly egg insulators, and even then you may end up with an unexpected resonant section. Common synthetic ropes have a stretch problem. Fortunately mylar rope has been designed specifically for antenna guying. When you use the proper size line, it is as strong as steel guy wire and its stretch, even on long runs, is negligible. The owners and staff of United States Rope (Note 4) will be happy to discuss the specs of their mylar guy rope with you. I used a set of mylar guys for 10 years before I decided it was time to replace them. The sun's UV light eventually weakens them, but in my experience, not any faster than my galvanized guys rusted. United States Rope tested my 10 year old line and found that although it was getting weaker, it still met the service specs I needed, so it was not about to fail.
Locating Materials

Getting supplies for antenna and other home brew projects can be a challenge. Check your telephone book's "Yellow Pages" for local electronics surplus stores. Sometimes "general" surplus and salvage stores will have an electronics section, or materials that you can use. Check local Universities and colleges as they often have public outlets where they dispose of their surplus electronic supplies and gear. Usually these sources are strictly "walk in" warehouses where sales staff will not know all that they have. Just wander around and look at all the goodies not normally available by mail or regular electronic suppliers. Cannibalizing cheap "junked" devices from these sources and from ham flea markets are good sources for "junk box" stock.

Additional sources for components for building projects can be found by going through the ads of ARRL and AMSAT publications. AMSAT and ARRL advertisers deserve your support as they help make these publications available at prices we can easily afford.