My Vibroplex Bug

The Straight Key Century Club (SKCC) does all of their work using mechanical Morse Code keys, as opposed to the electronic keys invented later. Most people will recognize the old telegraph key, where the person controls the dots and dashes. In 1905, Horace Martin had an interesting idea. He invented the semi-automatic key, which we call a bug.

A bug has a pendulum to form the dots. Pressing a paddle to the right activates the pendulum. Pressing the paddle to the left acts like a straight key for forming the dashes. If this sounds kind of strange then you have the right idea. This quirky instrument intrigued me, and I resolved to try one.

I took a trip to the Ham Radio Outlet in New Castle, Delaware. I wanted to try to return some things, and maybe buy some things. I met Ron and Mario, sorry I don’t have their calls. They did the best they could to accommodate my returns. If I had known that I only had ten days then I would have handled everything differently. Of course, then I wouldn’t have gone.

I asked about the Diamond X50A which I would eventually buy. I should have bought it on the spot, but I still didn’t quite know how I would mount it. As it turned out I mounted it perfectly on my window sill using the counterpoise as a tripod.

My friend Meg looked at some cool solar panels. I chatted with Ron and Mario. Eventually she asked if I had anything else I wanted to ask. We had driven there in the rain and they really did do their best with the returns. And admittedly, part of me wanted to buy something, like a kid at a toy store. I had an inkling.

“I’ve wondered about Vibroplex bugs. Do you have any?”

“Actually, we have a used one.” said Ron.

I knew I had to buy it. I asked if they could please take it out so I could touch it, since I can’t see it. I made it clear that I intended to buy it. They got it out and opened the box, and for the first time I touched a Vibroplex Original Standard Bug.

It really does feel like something invented at the turn of the last century, like an intricate pocket watch. It has a rectangular metal base. The pendulum arm sits towards the front of the base, with the paddle coming off the front. The paddle has two parts. On the left, it has a thumb-shaped piece of plastic. On the right, it has a plastic knob used for a straight key, but turned on its side, with the flat part facing outward. The pendulum’s weight sits at the back of the base under a metal hoop. The left side has three adjustment screws. The right side has one screw and the two contact screws for connecting it to your radio. Luckily I already had the proper cable. Vibroplex sells them. Perhaps coolest of all, you can hear the pendulum make the dots.

“It’s beautiful!” said Mario.

“That was Ken’s right?” one of them asked.

I learned that this key came from the estate of Ken Hartley, N2OHD, the former manager of the store. Meg recalled seeing a sign as we came in. He died at age 72.

“It’s as good as new. Ken was one of those hams who bought a lot of things and never used them.” said Ron.

“It’s beautiful!” repeated Mario.

I bought it and took it home, but quickly realized that I needed some help. I’ve adjusted all my other keys by touch, and figured if I fiddled with the screws enough then I would figure it out. Before I knew it I had reduced it to a nonfunctional mess. I emailed the SKCC. I knew they’d help, and sure enough they did. I received several helpful replies, and even offers for telephone training. One reply described the layout perfectly, and after some more fiddling I began to understand.

The bug sends and receives high speed code. I got it down to about 23 WPM, but I wanted to reduce it further. I purchased a Round Arm Vari-speed Accessory from Vibroplex. It adds an extra weight to the arm, but requires more adjustment. The heavier weight can cause bouncy dots. After a lot of practice I finally got it sounding good sending around 15 WPM.

The SKCC just had their Weekend Sprint, a relaxed contest which they have once a month. Each sprint has a theme, and for this month club stations counted for bonus points. I wanted to activate WM3PEN, the club call for the Holmesburg Amateur Radio Club. I had a headache most of the weekend, and I can’t do CW with a headache, but on Sunday night I felt well enough to drag myself on air, and to my delight I made three QSOs using my bug. I think Ken would have approved.

 When a ham becomes a silent key as we euphemistically refer to it, the ham radio community distributes their equipment. I promise that his bug, now my bug, will get plenty of use.

Adjusting the Bug

I wanted to give a quick reference in case any other hams, blind or not, wander upon this article. As noted before, the bug has three screws on the left, and one on the right. They perform the following functions, going from front to back on the left.

  • Dash gap
  • Dot tension
  • Dot pendulum gap
  • Dot contact gap

The right side has the screw to set the dash tension. The weight goes on the arm and has a screw to tighten it. The closer to the end of the arm, the slower the speed. If you use the Vari-speed accessory, it screws on to the end of the regular arm, then the weight goes on that. The vari-speed has a screw which tightens it. Use the included allen wrench to unscrew it, slide it onto the main arm near the end, then position the vari-speed’s arm and tighten the screw.

Setting it requires getting a feel for the way the four settings relate. The dot gap and dash gap complement each other, as do the dot tension and dash tension. The dot gap and dot contact control the length of the dots. Many people get this wrong, resulting in so-called machine dots. Use an electronic key for reference. I first set the gap, then adjusted the contact, which also changed the tension. Easy does it… Each screw has a metal ring to lock it in place. Make sure to do this once you’ve found a good setting.

The pendulum requires a certain amount of space to get enough force to swing. If you set your spacing too narrow you won’t get a long string of dots, just a sad V. If you set it too wide it will cause extra force, then you will get bouncy dots. I’ve found that bouncy dots can also happen from setting the Vari-speed too far up the main arm.

I hope these notes help someone. I love the idea of sending high speed code mechanically. Why not!