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The Amateur Amateur: Standoffish

05/16/2012

By Gary Hoffman, KB0H
Contributing Editor

It was a matter of getting more metal into the air. That’s what started it all. I had hundreds of great ideas -- perhaps a dozen that I might actually be able to do -- but only three of four transceivers with which to do any of it. The real limitation, however, was that I only had two antennas up, and only one of those could see over the hill to my south. And as you probably guessed, pretty much every station I needed to contact was to the south of me.

The Good, the Bad and the Ugly

There were four masts on my house. One -- at the south end of the roof -- held a television antenna and was useless for Amateur Radio operations. It wasn’t high enough and would have required a ridiculous length of feedline to reach. The other three masts were clustered near each other at the north end of the roof. I really should have spread further apart, but at least they were all at different heights.

One of the north-end masts was made of one-inch diameter aluminum tubing and reached 10 feet above the roofline. It held two scanner antennas and wasn’t really high enough to be of any use. The next one was made of one-inch diameter steel tubing and went up 15 feet. It held a discone antenna that worked modestly well.

On good days. More or less.

But the most imposing structure on the roof was the two-inch diameter, 21 foot high steel mast. It was a Penninger Tipper, meaning that I could unbolt and swivel the mast down until it was horizontal. Very handy for maintenance. One person could do it alone, although a couple of Motrin would probably be in order afterward. That mast held my main dual-band antenna, and it just peeked over the hill to the south.

I thought a lot about how to get another antenna up there. Putting up more masts didn’t seem like a good idea. Besides, I already had a nice 21 foot mast. Wasn’t there some way to put more antennas on it?

Hypothetically, yes. An antenna can be attached to the side of a mast using a device called a standoff. Basically, a standoff is just a metal structure that attaches to a mast and holds an antenna a few feet away from it. It doesn’t have to be at the top, it can be anywhere along the mast.

Hang ’em High

Having formulated a plan, I started looking for standoffs on the Internet.

It was a frustrating search. I found standoffs for chimneys, vent pipes and immense broadcast towers, but nothing that would work on my two-inch steel mast. If you happen to manufacture something like that, I'm sorry, but I missed your website.

All was not lost, though. I eventually did find a standoff on the web that looked very promising. It was a tad expensive, but looked like it was the right size and would do just what I wanted.

I put in an order and waited.

A few days later my standoff arrived! I came home from work and there was a big box on my porch. I knew exactly what it was. Gleefully I took it inside the house and opened it.

Ha-ha-ha! Just kidding! What really happened is that I tried to take it inside. I tried to open it. It took a lot more muscle power than I’d anticipated. And even after I’d wrestled the box into the house, I still couldn’t open it. Someone had sealed it shut with about 400 of those huge box staples. It took nearly an hour to pry them all out.

But persistence (or obstinance) finally paid off and I was able to open the box. And there was my standoff. It was pretty much the size and shape that I’d expected, but the weight! I could barely move the thing!

Okay, I’d made a mistake. This standoff was clearly for industrial usage, meant to be installed on seriously high masts and built to withstand impacts from stray meteors. It weighed almost as much as the mast on which I had intended to mount it. There was no way that I could use it. Even if I decided to try, I would’ve had to rent a crane to lift it up to my roof. A big crane.

For a Few Dollars More

So now I had two problems. I needed to get rid of the monstrosity I just bought, and I still needed a standoff for my mast.

Not wanting to throw away or melt down the chunk of steel that I ordered -- and absolutely not wanting to re-box and try to ship it -- I decided to give it away. Fortunately Roger Volk, K0GOB, said that the Missouri Emergency Radio System could use it and happily took it off my hands.

As for my second problem, I came to the conclusion that the only way to get a standoff that would suit my needs would be to build it myself.

About time! some of you are thinking. But you have to remember that I’m just an amateur amateur, and not all that adept with mechanical things. I don’t have a lot of tools for fabricating stuff. In fact, I didn’t even know what to use for raw materials.

Poking around in my junk (I do have a lot of that), I thought I might try a using a couple of old aluminum mast sections. I do have a drill, so I figured I could drill some holes in the old sections of mast, run some u-bolts through them, and with luck, clamp my Mark II standoff onto my 21 foot mast.

I did drill a few holes. All the time, though, I wondered about the stability of the final configuration. Round mast sections clamped to another round mast just didn’t seem right. I was also concerned that the aluminum mast sections, laying horizontally, might not be strong enough to hold the antenna I wanted to put on them. I needed something to strengthen the aluminum mast sections and give them a better purchase against the main mast.

Time for a trip to the hardware store. I didn’t know what I was looking for. I just hoped that something would jump out at me.

Something did. Angle irons. They were steel. They were long enough. They weren’t too heavy, and they already had pre-drilled holes.

Perfect.

The only thing that still worried me was how to connect the aluminum mast sections to the angle irons.

And then it hit me. I didn’t need the aluminum mast sections. All I needed was the angle irons!

I bought a couple of angle irons, took them home, and started bolting together my standoff Mark III. It went together surprisingly quickly.

Well, that seemed too easy. But I got up on the roof of my house, lowered the Tipper (two Motrin for sure), and started bolting the Mark III to the main mast. I made the obligatory blood sacrifice (one small Band-Aid) and everything looked snug and stable.

Still thinking that it was all going too smoothly, I took my secondary antenna up to fit it onto the Mark III. Hmmm. No problems. (I am skipping the really ugly part about routing the coax. I don’t want to even think about that, let alone write about it.)

I placed the standoff so that half of it was facing to the east of the main mast, and half was facing to the west. I did this so the weight would be evenly distributed. Looking at it, it occurred to me that I could actually place two antennas on it.

So I did.

A Fistful of Dollars

Yeah, I know. I shouldn’t have placed two antennas at the same height, especially so close to each other. But I justified my decision by convincing myself that the big two-inch mast would be between them and would, perhaps, shield them from interfering with each other.

Besides, two antennas looked prettier than one.

As it happened, blind luck was with me and the two antennas did not interfere with each other. Both, however, interfered with the main antenna at the top of the mast.

I tipped the mast one more time (two more Motrin but no more Band-Aids), and lowered the standoff a foot and a half.

Voila. Success.

Proud of myself, I asked my wife Nancy to take a look at my handiwork.

“It looks like Voltron!” she exclaimed.

Well, I guess it does.

But it works.

Editor’s note: ARRL member Gary Hoffman, KB0H, lives in Florissant, Missouri. He’s been a ham since 1995. Hoffman says his column’s name -- “The Amateur Amateur” -- suggests the explorations of a rank amateur, not those of an experienced or knowledgeable ham. His wife Nancy is N0NJ. Hoffman has a ham-related web page. Readers are invited to contact the author via e-mail.



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