Station Activities: Paddle repair, Iambic A vs. B, first dipole

A couple of weeks ago, I purchased a highly-modified Vibroplex Standard paddle. Apparently, in making the modification, the previous owner had lost one of the trunnion screws and decorative red dots. As you can see in the photo below, the previous owner found a brass screw to use in place of the missing trunnion screw.

While the paddle worked just fine, I wanted to use the correct parts. Fortunately, these parts are still available from Vibroplex, and I purchased them from Vibroplex. Each part cost $5. I can see charging five bucks for the screw, but I think that $5 for the little piece of plastic is a bit much. Not only was it expensive, it doesn’t even match the dot on the other paddle lever.

At any rate, the parts arrived Friday, and it was relatively simple to install the trunnion screw and get it all adjusted and working properly. I’m still not sure what I’m going to do about the red dot. At the very least, I’m going to complain to Vibroplex about it.

Iambic A vs Iambic B
After getting the paddle back together, I connected it to my WinKeyer and started playing around with it. I was getting some odd behavior, though. It didn’t occur to me at first, but the problem was that the batteries in the keyer were getting weak. Before I figured that out, I’d done a factory reset and tried reprogramming it. Only when all that didn’t work, did it occur to me that the batteries needed replacement.

Even after I’d replaced the batteries, I was getting some odd behavior. When sending CQ or my callsign, I wasn’t getting the final “dah.” After puzzling about this for a while, I figured out that the problem was that I’d programmed the keyer to operate in iambic mode A, and previously I’d been using mode B.

Chuck Olson, WB9KZY, describes the difference between modes A and B in his article, What’s all this iambic keyer mode A and B stuff, anyhow? He says,

The difference between mode A and B lies in what the keyer does when both paddles are released. The mode A keyer completes the element being sent when the paddles are released. The mode B keyer sends an additional element opposite to the one being sent when the paddles are released.

In mode A, to make the K or Q, you actually have to hold the dah lever down until the dah actually starts being sent. Since I’d been operating in mode B, I guess I got a little sloppy about doing so. In mode B, the keyer automatically sends the dah, but in mode A, it doesn’t, and that’s why that last dah would sometimes get dropped whiles sending a K or Q. I now have the keyer programmed to operate in mode B, and everything is working just fine.

A new ham’s first dipole
Yesterday, I spent a couple of hours helping a new ham set up his first dipole. Last weekend, he actually got the dipole up in the air, but when he connected it to the rig, it just wouldn’t load up. After swapping some e-mail about the problem, we decided that it would be best if I came over and had a first-hand look. So, yesterday morning, I threw my box of antenna goodies into my car and headed over there.

Taking my advice, he’d purchased a spool of coax and crimp-on connectors. I didn’t ask him where he’d purchased the crimper, but the first thing I noticed is that his crimps didn’t look right. They were much too tight. He got out his multimeter, and sure enough, the coax was shorted. We cut off one connector and measured again. The coax was still shorted. We cut off the other one and measured both connectors. Both were shorted.

I had brought my crimper and compared mine to his. His crimper had two dies for crimping coax – .213-in. and .255-in. My crimper also has two dies: .213-in. and .235-in. The instructions say to use the .235-in. die for crimping RG-8X connectors. He had used the .213-in. die, which really squeezed the coax. While I can’t actually see the short, my conclusion is that somewhere along the crimp, the shield became shorted to the center conductor, perhaps aided by the heat of soldering the center conductor to the connectors center pin.

Fortunately, he’d bought spare connectors. We put those on, using the .235-in. die on my crimper, buzzed out the cable, and we were in business. We connected the cable to the antenna, connected my antenna analyzer to the other end, and found that the antenna was resonant at 6.9 MHz. After taking about a foot off either end, we pretty much centered the resonant point of the antenna, and as one former president once said, “Mission Accomplished!”

The moral of the story is that you really need to use the right crimper and the right die for crimping coax connectors. My friend certainly had a quality crimper, but didn’t use the right die. He may have been able to use the .255-in die, but I don’t think that would have made a secure enough crimp. .235-in. is just the right size for RG-8X coax.

Speak Your Mind

*