Part 26 "Wanna Tinker" Construction Project Series

By Dick Kelly, W6BKY, W6BKY@aol.com

Have I mentioned that, for several years, my home was a sailboat? Well, it’s true. Living aboard a sailboat on the California coast is a wonderful lifestyle, and I’m happy to have had the opportunity to do so.

One day during the summer of 1980 (good heavens, was it really twenty years ago?!) I had a few people aboard for an outing on San Francisco Bay, and a woman remarked: "How sweet, you keep peanut butter aboard for your kids." While it’s true that the peanut butter was available to kids, or to anyone who appreciates the virtues of peanut butter, the real reason I had it aboard was that I love the stuff. Peanut butter is high in protein and contains no cholesterol. Not only that, it is cheap, requires no refrigeration, and when mixed with various other foods, makes a quick meal. What more could you ask of your groceries?

Having said all that, what is r-e-a-l-l-y neat about peanut butter is the jar it comes in. It almost always comes in a large-mouthed jar that, when emptied and thoroughly washed, can serve many useful purposes around the Ham Radio station and workbench. (You were wondering what all this had to do with tinkering, weren’t you? Well, now you know.)

Perhaps the most obvious, and one of the most useful tasks served by peanut butter jars is that of storage. I have dozens of peanut butter jars of various sizes holding nuts, bolts, screws, resistors, coils, capacitors, relays, and many other small parts. Useful as they are as storage devices, there are other, more exotic uses for peanut butter jars. I will share a couple with you, and I’m sure you can come up with additional uses for these wonderful castaways.

In 1991, when I bought my current QTH, I was truly shocked by the sticker price on real estate. My dream of an expansive antenna farm soon wilted and died in the face of asking prices for houses along the California coast. I know, there are less expensive places to live, but I like the Southern California coast; what can I say?! In any event, the XYL and I finally settled for a small house on a tiny lot in Ventura. This is definitely NOT the ideal place for an antenna farm. There is hardly enough room for a modest antenna garden. My first antennas were two attic dipoles for 15 and 20 meters with a common feed point. These worked out surprisingly well until the end of the sun spot peak, then I began hearing fewer and fewer signals. To make a short story even shorter, I decided to erect a vertical for the low bands (160 through 30 meters). Verticals have a relatively small footprint, and are ideal for small areas. The vertical, by the way, works great, even on 160 meters, which brings us to another use for the peanut butter jar.

My vertical is about 50 feet tall. It’s what I call my "Hardware Store Special", and is fabricated from (mostly) galvanized iron pipe. The antenna swivels at about the twelve foot level, and can be lowered so it rests on my roof. This allows me to tinker with the upper sections. With an impedance matcher (sometimes called an antenna tuner) I got great results on 80, 40, and 30, by simply feeding the base of the antenna with 50 Ohm coax. 160 meters, however was a different story. My best DX on 160 was Colorado. Through trial and error, I discovered that I could work the East Coast of the U.S., Canada, Mexico, the Caribbean, and Japan if I added a loading coil at the base of the antenna. The problem is that the loading coil had to be switched out of the circuit for all bands except 160. I accomplished this with a simple jumper and alligator clip. This, of course, required going into the back yard to change the jumper. During the long Southern California dry season this is no problem, but it does (occasionally) rain in the winter, so I decided to install remote switching at the base of the antenna. The simplest and easiest way to do this is to install a relay, but this requires weather-proofing of some sort. Enter: PEANUT BUTTER JAR!

I mounted a relay on a piece of sheet aluminum cut to fit the under side of the peanut butter jar lid. I used weather-proof feed through connectors for RF and the relay voltage. The lid is screwed onto the jar, then sealed with caulking (I used some marine grade caulking left over from my boating days). The jar is mounted "bottom-side-up" near the base of the antenna and, presto!, I have my weather-tight relay for switching 160 meters in/out of my vertical antenna feed point.

Speaking of 160 meters, loading coils, etc., my very first 160 meter antenna was an indoor random wire. At the time, I was living in an apartment in the San Francisco Bay area. The apartment had no attic, but it did have about 4 feet of crawl space above the ceiling. I wound about 60 feet of wire around the crawl space, then down through a hole in the ceiling to the rig. I used wire salvaged from deflection coils in a discarded TV set. Sixty feet is a puny antenna for 160, and a loading coil was required, but I had no large coil stock on hand, which brings us to yet another use for peanut butter jars: as forms for large coils.

I always have an empty peanut butter jar, or two, on hand, so I selected the largest one I could find and wound insulated copper wire around it to fashion a coil. The wire I used was ordinary household wiring, probably about #14. No, I didn’t take it from the apartment; it was scrap I had found at a construction site. I removed insulation from several spots to serve as taps to provide for adjustment, then secured the wire to the jar with tape. "What was the inductance of the coil?", you might want to know. I have no clue. I simply would all the turns I could get onto the jar, thinking that, for 160 meters, I needed all the inductance possible. Wonder of wonders, it worked!. "How well did it work?", you might ask. Actually, this simple, quick, and cheap antenna did surprisingly well. Reviewing my log, I see over 40 different stations worked on 160 meters during the first week. Not too shabby for an antenna that cost practically nothing and required only a couple of hours to build and adjust.

Want more used for the peanut butter jar? OK, how about a deluxe, water cooled dummy load. Actually, the peanut butter jar is not the load, it just contains the dummy load. Here’s how it works …

First of all, you need a rather large peanut butter jar if you are going to be using your dummy load for up to 300 watts, or so. For QRP, the jar can be much smaller. I’ll give details for the QRO (high power) version, then you can scale yours according to your own needs. The peanut butter jar I use is about seven and a half inches tall and about four inched in diameter. Be sure both the lid and the jar are thoroughly clean.

Figure 1

Mount a female coaxial connector in the center of the lid, as shown in Figure 1. Notice the backing plate. Lids are very thin sheet metal, and must have some sort of backing for the Coax fitting. I used a piece of scrap aluminum about one sixteenth of an inch thick, cut to fit the under-side of the lid.

Poke a small hole somewhere in the lid for venting of gas. (A nail makes a nice punch for poking holes into peanut butter jar lids.) Remember, you may be pumping up to 300 watts of RF energy into this thing, so heat will build up if you use it for more than a few seconds.

Two electrodes are required for the dummy load, one connected to the center conductor, and one connected to the shield, or "ground" side of the coax connector. See Figure 2.

Figure 2

The electrodes must have a relatively large surface. There are several methods that can be used to fashion the electrodes; three are shown below.

1) Strip the shielding from RG-8/U coaxial cable, flatten it, then coat it thoroughly with solder.

2) Use strips of aluminum or copper.

3) Solder several pieces of bare hook-up wire together in parallel, or use large stranded wire about #12, or so.

I used a salvaged grounding strap from old TV sets for the "ground" electrode. The strap is very thin (about the thickness of a soft drink can), about three-eighths inch wide, and long enough to reach the bottom of the jar. I suppose strips cut from a large soft drink can serve if you remove the paint or dye (or other covering) from the can.

For my other electrode (the one that is soldered to the center conductor of the coax connector) I used two pieces of stranded copper wire, thoroughly covered with solder. "Why didn’t you use a salvaged ground strap for the center conductor electrode?" you might want to know. Good question, and here’s the answer …

The ground strap, being aluminum, can not be soldered. Well, aluminum can be soldered, but it’s more trouble than its worth to do so. The aluminum is OK for the ground electrode because it is fastened to the connector with a screw and lock washer to provide a good electrical connection.

Whatever you use for electrodes, you will need four of them. I will explain the use of the two "extras", at the appropriate time.

The electrodes must be as far apart as possible inside the jar. This is accomplished by bending them outward so they are a bit farther apart than the diameter of the jar. Then, when you insert them into the jar, they will "hug" the walls of the jar and keep themselves separated, as shown in Figure 2.

At this point, the curious reader, such as yourself, may be wondering what in the world goes into the jar that turns it into a dummy load. The "secret ingredient" will be revealed next time. ‘Til then …

73, Dick, W6BKY