30m: An Interesting Little Band

For the past couple of weeks, I’ve been operating on 30m. Overall, I’ve made about 40 contacts, including a handful of DX contacts. Here are some impressions:

  • It is a little band–only 50 kHz wide, with most of the activty in the lower 20 kHz of the band.
  • Propagation-wise, it’s a cross between 20m and 40m. Lots of domestic contacts, but more DX than on 40.
  • The average speed of the CW ops on the band seems to be higher than on 20m or 40m. I guess this is because the dominant mode on the band is CW, so the more proficient CW ops tend to migrate there.
  • The DX stations on 30m are in countries that I never heard on 20m. For example, the other day I heard stations from Northern Ireland and the Ivory Coast.
  • There’s not enough activity! A lot of times it seems that the band is open, but there are just not enough stations on. Maybe it’s time for a 30-30 club to encourage activity.
  • One guy said he thinks that the folks on 30m are friendlier than the ops on the other bands. I don’t know if that’s true–I’ve had many nice QSOs on 20m–but it may be that the percentage of friendly ops in higher on 30m.
  • Activity does pick up on the weekends when there are big contests. Today, for example, the band was really hopping due to the CQ WPX contest on the traditional ham bands.
  • There are a lot of hams with 1×2 calls on the band. I don’t know why this is exactly.

All in all, I’m really enjoying 30m. I just wish it was a little more active.

Heathkit Lives!

The Heathkit Company has been out of business for quite a while now, but many hams are still using Heath gear. As I’ve noted in an earlier blog entry, I recently resurrected a Heathkit keyer, which has been working like a champ ever since. I also have a Heathkit Triple Output DC Power Supply that I use when playing around with circuits.

I guess I’m not the only one still playing with Heathkits, as I just stumbled upon The Heathkit Shop. This website has all kinds of free information including a nice page full of links to information on the Heath Co. and their ham radio gear as well as repair guides for the HW-8 QRP transceiver, HP-23 high voltage power supply, HM-102 HF watt meter, HWA-202 Power Supply, HD-1410 Electronic Keyer, and HW-202 Two Meter Transceiver.

They also sell a few products, including a replacement PC board for the HP-23 power supply, a replacement display board for the SB104, and a coffee mug with the Heathkit logo. They also have just published a new edition of the HW-8 Handbook, which is a compendium of information on the HW-7, HW-8, and HW-9 transceivers. The book has all of the factory service updates as well as articles on troubleshooting and modifying these rigs.

All in all, it’s a very cool site.

The Slinky Antenna

I used to work for Jon Titus, KZ1G, when he was editor of Test&Measurement World magazine. In addition to being a fine editor, he is the developer of the Mark-8 Minicomputer, which some folks consider to be the first personal computer. He published an article on how to build this computer in the July 1974 issue of Radio-Electronics.

In addition to being a personal computer pioneer, he’s also been a ham radio operator for a long time. At one point, he acquired the patent from the inventor of the Slinky antenna and sold them for a number of years. The patent has since expired, but he still owns the trademark.

I found out about this one day while we were talking about antennas. He was so enthusiastic about the antenna, I said that I’d have to try it for myself. He said that even though he no longer sold the antenna, he thought he still had some of the parts, and that he’d look for them when he got home. A couple weeks later, a package arrived containing two Slinkies, a center insulator, two aluminum clips, and an instruction sheet.

The Slinky dipole antenna, for those unfamiliar with it, uses two Slinky coils instead of wire for the dipole elements. The Slinkies used for the antenna have a bigger diameter than the Slinky toys. This allows you to use fewer turns than if you used the Slinky toys for your antenna. Jon had these coils specially made.

When stretched, the Slinkies form are helical coils. To keep the coils horizontal, you must string a rope through the Slinkies and attach the rope to the antenna suports. I use a pulley attached to my house as one antenna support and a tree branch for the other.

The length of a dipole made with Slinkies as the elements is much shorter than a dipole made simply of wire. In fact, the instructions recommmend that the overall length of the antenna be no more than a quarter wavelength and can be much shorter. You tune the antenna by shorting out a number of coil windings with the aluminum clips.

A Long Time Coming
I hate to admit this, but it took me years to actually build the antenna. What finally prompted me to do so was that our club set up a multi-op station to work the Michigan QSO Party. I figured that the Slinky would be easy to set up and tune, and beause it’s a short dipole, could fit in a small space if need be.

As it turned out, it was all of that. At first, we decided not to use the antenna. Our host had erected an 80m bazooka antenna, and one of the other guys had brought a multi-band trap dipole. Because we only planned to operate two transmitters, we figured that we’d use a tuner to load up the bazooka on 40m, and use the trap dipole on the higher bands.

As it turned out, however, we weren’t able to get a good match on 40. So, we scrambled and put up the Slinky, tuning it to 40m.

At first, we thought there was something wrong with the antenna. While Tom and I struggled to erect the thing, Sam was reading the SWR with my antenna analyzer. At one point, Sam said, “The SWR looks pretty good now,but it’s jumping around.” I asked myself what could be wrong– bad solder joints, bad coax?

I went downstairs to see for myself. The measurements were indeed jumping around, but as I puzzled over this, I soon noticed that the SWR jumped whenever the operator of station #1 began sending. What we were reading was not a high SWR, but rather RF being emitted by the first transmitter!

After solving that little teaser, we hooked it up to the Drake Twins we were using on 40, and it worked solidly, if not spectacularly for the rest of the day. When we decided to pack it in, it took us only 15 minutes to take it down.

Last weekend, I strung it between two trees in my front yard so that a friend and I could work two transmitters in the Fists Spring Sprint. Despite being only 15 feet off the ground, it worked well despite poor band conditions.

The next day, I took it down and put it up in my backyard, tuning it to 30m instead of 40m. I’m working almost everything I can hear, and getting good signal reports in the process.

One thing I notice about the antenna is that it doesn’t like being wet. The SWR goes from about 1.1:1 to almost 1.4:1 when it rains. Maybe that has something to do with the supporting rope.

Despite it working so well on 30, I think I’m going to put it back on 40. There just isn’t enough activity on 30 for my taste. More about 30m later.

Links
Here are some links describing the Slinky Antenna and variations on the theme:

The RigRunner and Anderson PowerPoles

I finally broke down and bought the RigRunner/PowerPole Starter Package from PowerWerx. The RigRunner is simply a distribution panel for the 12V power that runs all of the solid state devices in your shack.

I bought the Model 4008, which includes an input connector and eight connectors for your rigs. Each of the connectors is an Anderson PowerPole connector. Each is separately fused, using automotive style fuses for ease of use and widespread availability. There is also a small circuit that measures the input voltage and three lights that note whether the voltage is normal, overvoltage, or undervoltage.

The RigRunner is a great design and well-made, but gives the impression that it is overpriced. It is, after all, just a patch panel. You could, of course, build it yourself, but that takes time. So, the question is how much your time’s worth.

Unfortunately, the documentation provided by the manufacturer is not really very good. I could not find any instructions on how to crimp the contacts and insert them into the housings. Unfortunately the Anderson website was not much help, either.

I ended up criming the contacts with a cheap electrical crimper, and in doing so deformed the contact enough so that it was difficult to insert all the way into the housing. After much cajoling, I did manage to force it all the way in, but it wasn’t pretty. I think I’m going to go buy the right crimper. That will be another ten bucks.

I wish I’d read the assembly instructions on the Wake County RACES/ARES website. It would have saved me a lot of grief.

In the end, though, I’ll have a versatile system capable of supply the proper voltage to both my HF rig and my VHF rig as well as any other accessories in the shack. Not only will it make setup and teardown easier, but it will also give me the added reassurance that each of the lines is fuse-protected.

UPDATE 3/12/12: I did eventually purchase a Gardner-Bender crimper similar to the one that’s referenced on the Wake County RACES/ARES website. I think I paid about ten bucks for it. It has one position to actually make the crimp and a second position to  make the terminal barrel round again. It works just fine.

I have since purchased the Tri-Crimp crimper sold by PowerWerx. It costs more ($40), but it was designed specifically to crimp PowerPole terminals, and when used properly, produces a perfect crimp. I also purchased the insertion/extraction tool. It works OK, but it’s probably not worth the money. A small screwdriver with a fine blade works just as well, if you ask me.