Here Comes the Sun (doo doo doo doo)

Mike, K8XF, sent this link to this NASA news item about a prediction for the next peak in the sunspot cyle. According to Mausumi Dikpati of the National Center for Atmospheric Research (NCAR), “The next sunspot cycle will be 30% to 50% stronger than the previous one,” she says. If correct, the years ahead could produce a burst of solar activity second only to the historic Solar Max of 1958.”

Sounds good to me.

More Kits

This from “rwr01″ on the radiokits Yahoo Group:

I came across the Kit Radio Company the other day. They advertise some nice professional looking radio kits. They offer a Superhet, a Regenerative, a TRF and a DC receiver (all transistorized) and a couple of (looks like VXO) transmitters too! They’re based in England but shipping overseas doesn’t add much to the cost as they simply don’t include batteries when they ship overseas.

Their KRC-2 Shortwave Regenerative Receiver is reminiscent of the Science Fair Globe Patrol featured on this group’s main page. Looks like it might have resistive rather than capacity feedback though as it says regeneration is unaffected by receiver tuning or antenna coupling.

Miscellaneous Links

Here are some miscellaneous links that I’ve come across lately:

  • Extra Class Math Guide. On the Extra Class test, they actually expect you to know how to calculate things like resonant frequency and phase angles. If you don’t remember your high school math, download this free guide.
  • Nightfire Electronic Kits. Want to start playing around with surface mount devices? Nightfire offers collections of resistors, capacitors, and semiconductor devices, as well as prototype boards. They sell complete kits, too.
  • Hardware Book. This site bills itself as, “The Internet’s largest free collection of connector pinouts and cable descriptions.” Need to know how to wire up an Amiga 500 mouse? This is the site to go to.

Bug Advice

On the qrp-l.org mailing list, Doug K4DSP offered the following advice for using a bug:

  1. Get a decent bug. A piece of junk will sound like a piece of junk and you’ll get frustrated very quickly. You can still buy new bugs from Vibroplex for less than $200. You only buy quality once.
  2. Whether you buy a new one or a used one (and especially if you buy a used one!) download the Vibroplex adjustment guide from Vibroplex and read it.
  3. Get or make an additional weight so you don’t send dits at a ridiculous rate.
  4. Practice.

This is good advice. #1 especially resonated with me. I bought a cheap one off EBay, and I regret it. I can’t seem to adjust it properly and it generates flakey code.

A Modest Proposal for Two New Q-Signals

Yesterday, three of us carpooled to the Marshall Hamfest, about an hour west of Ann Arbor. On the way over, we got to talking about CW. Jack, WT8N, a relatively new ham who has—I am happy to report—taken up CW, noted that one thing he found puzzling was that it seemed to be common practice for guys to say how old they are and how long they’ve been hams.

To be honest, I’ve always found that kind of curious, too. In fact, I rarely volunteer this information unless prompted to do so. Jack even went on to say that there have been some contacts where guys would ask if he did not offer this information.

Now, I don’t want to get into the psychology of this particular practice. I’m no psychologist. What I would like to do, however, is to make passing this info quicker and easier. Especially since it appears this has become a common operating practice.

So, what I’d like to propose is that we create two new Q-signals. The first, QHO, will stand for “I am __ years old.” So, instead of sending “AGE HR IS 51,” I can simply send “QHO 51.”

Since the number of years one has been licensed often follows this bit of information, e.g. “AGE HR IS 51 ES BN HAM 35 YRS,” I propose adopting a second Q-signal, QBH. We’ll use QBH to mean, “I’ve been a ham for __ years.”

Now, according to Ralf D. Kloth, DL4TA, QBH has been used in the past in the aeronautical service to mean “I am flying below cloud and at flight level/altitude …” or “Maintain a vertical distance of … (figures and units) below cloud.” I doubt that there will be much confusion, however, if hams adopt QBH for the meaning I’ve just described.

Of course, adding a question mark to the Q-signal will turn it into a question. So, if you would like to know the age of a ham you’re in contact with, send QHO? If you want to know how long they’ve had their ticket, send QBH?

WATSA OMS?

Searching for Parts? Search With These Web Services

Chris, KA8WFC, sent me a lead for Octopart, a search engine for electronics parts that searches the stock of Mouser, Digikey, Newark, and Allied. Rich, KD6HWF, also pointed out that FindChips.Com does the same thing, but with more vendors.

I tried both searching for the elusive 1N34A. Both websites show that Mouser has them available for $0.51 each, and that Newark has them for $1.15 each. FindChips did come up with a bunch of other suppliers, but it looks as though you’d need to contact them for a quote, and that you probably couldn’t buy just one or two from them.

Don’t Like MFJ? Here Are Some Antenna Analzyer Options

On the Elecraft mailing list, there’s been a flurry of e-mail discussing antenna analyzers. The most popular antenna analyzers is the MFJ-259B. As is often the case when MFJ equipment is discussed, there was much wailing and gnashing of teeth. Fortunately, the thread did not turn into simply a “bash MFJ” item. Instead, several guys suggested alternatives:

  • miniVNA. This analyzer is available from WiMo in Germany. This unit has several nice features, including a frequency range of 0 – 180 MHz and computer integration. Unfortunately, the latter is also a drawback, as this analyzer cannot be used without a computer. Cost: 255 euros (about $350 USD).
  • VK5JST AERIAL ANALYSER. This is a kit sold by the South Coast Amateur Radio Club, Adelaide, Australia. This looks like a nice unit, and as the guy who suggested it says, “The price is good and you get the added bonus of making it yourself.” Cost: about $110 USD, including shipping.
  • AMQRP AA-908. This is a project of the American QRP Club. This is built on top of the Micro 908 board. The price is kind of steep—$230—if all you want is an antenna analyzer, but you can also make the unit into a PSK modem, DSP audio filter, and an intelligent signal generator.
  • N2PK VNA. This is a real homebrew project. Printed circuit boards are available, but no complete kits are available. Larry, N8LP, commented, “The N2PK is an awesome piece of gear for the money.”
  • Autek RF1, VA1. I suggested looking at either the Autek RF1 or VA1. They fit in the palm of your hand, are inexpensive ($150 for the RF1 and $200 for the VA1), and work pretty well. They’re certainly accurate enough for most amateur radio antenna work. Disadvantages include the lack of a computer port, finicky tuning, and the lack of an analog meter.
  • Tenna Dipper. If you’re really on a budget, get a Tenna Dipper from the 4 States QRP Club. It only outputs one frequency per band, and you can only use it for 50-ohm systems, but only costs $25.

There are other options from Kuranishi, TimeWave, and AEA, but they’re very expensive. They may be worth the money, but are probably overkill for most amateur radio applications.

The “Almost Random” Wire Antenna

I’m still amazed at the success I’m having with my random wire antenna on 80m. Yesterday, I worked a guy who said he was running 500W. He was, of course, 599 here, but he gave me a 589. There’s now no doubt in my mind that a random wire can be an effective antenna.

On the HamRadioHelpGroup mailing list, there was a related discussion about the “almost random” wire antenna. The idea is that some lengths just won’t work well on one or more bands. In general, you want to avoid choosing a length that is a half wavelength, or multiple of a half wavelength of a band that you want to operate.

Tim, N9PUZ notes:

I have used the 49.2 ft (15 Meter) length of wire on vacation with both automatic tuners and an MFJ Model 16010 tuner with good results for 40, 20, 17, and 15 Meter operation. This is not as good an antenna as a dipole or doublet in my opinion but it’s a workable antenna.

Moe, AB8XA, added:

With all the bands we have at our disposal, finding an end-fed antenna length that’s not near 1/2 wavelength on some bands is tough, impossible for me so far. As far as dodging 1/2 wavelengths, 86.9′ may be the best compromise for most bands. Using 95% velocity factor, I find 86.9′ roughly 1/3 λ on 80 m, 2/3 λ on 40 m, 4/3 λ on 20 m, 5/3 λ on 17 m, 7/3 λ on 12 m, and 8/3 λ on 10 m (2.60 – 2.73 λ). But it is exactly 1/2 λ on 60 m, and 0.94 λ, almost 3/3 or 2 half λ, across 30 m, and 1.95 – 2.00 λ, or 6/3 and 4 half λ, on 15 m.

My IC-718 doesn’t have 60m, so slightly shortening the 86.9′ may make it possible to tune 30 m and the lower, CW end of 15 m. But that might bring the lower end of 10 m too close to 2.5 λ.

It appears to me, with an integrated tuner in the radio, which may not have the tuning range necessary for some bands, or even with a wide-range tuner in the shack, the end-fed brings the antenna inside and close to the operator. A remote automatic wide-range tuner, such as the Icom AH-4 or SGC SC-230, between the end of the antenna and lengths of coax and control cable to the shack, appears to me might resolve that problem.

One of these tuners mounted well away from the shack, and close to the ground to feed the required radials, also offers the opportunity to turn an almost all horizontal wire into an inverted-L. From what I’ve seen playing with some modeling software, adding some vertical portion to the antenna can slightly ease the cloud-burning effect of a relatively low horizontal run on lower frequencies, as well as significantly reduce the depth of the nulls of a long horizontal wire on higher frequencies. But I’m sure no antenna expert. It’s always been my toughest subject.

My antenna is 85-ft. long, so I bet I can get mine to load on nearly any band. My next project is to connect it so an SGC-239 automatic antenna tuner that I have and just see what I can do on bands other than 80m.

Homebrew a DC Power Supply Load

I thought you all might be interested in a recent thread on the HamRadioHelpGroup mailing list. One guy had just purchased a 40A power supply and wanted to be sure it could supply the full 40A before he connected his transceiver to it.

He sheepishly described his first attempt—using a 100A car battery tester as a load. Predictably, it tried to draw 100A, and the power supply promptly cut the voltage so as to not overload the supply. I told him that that was probably a pretty good test. He now knows that his supply will not burn itself out if he puts too big a load on it.

He then thought about using headlamps as the load, but couldn’t figure out how to do that exactly. I said that might not be a bad idea, and gave him some advice on how to figure out how many he needed. Headlamps have a power rating, just like any lightbulb. You can then figure out the approximate current draw with the equation

I = (power rating)/13.8

Connect as many in parallel as you need to draw 40A.

Rod, KD0XX, then pointed us to this homebrew power supply load (pictured at right). This is basically a homebrew, air-cooled, power resistor. This is a fairly ingenious solution, imho.

The solution that the guy finally adopted is this variable load battery tester from Harbor Freight. It’s certainly a more versatile load than the homebrew version, but at 50 bucks, it’s also a lot more expensive.

DXTuners.Com Free (for a while, anyway)

DX Tuners provide access to a global network of remotely controlled shortwave and VHF/UHF receivers via the Internet. You aune the radios with your browser and get live audio. Normally, you have to pay to get access to all of the network’s receivers, but to celebrate the tenth anniversary of the launch of DxTuners.com, they are opening the network to everyone free of charge.

Check it out. It’s pretty cool.