Wish I’d Have Thought of This…

On the Ten-Tec Omni VII mailing list, Bert, W0RSB, reported on his recent experience with Customer Service. He said,

Rig came back this past Monday, a day early. The auto tuner now appears to be working correctly. Unfortunately, the invoice simply says “Could not duplicate complaint.”

Maybe being manhandled by UPS or being poked and prodded by the service tech bounced something into place. At any rate, this exercise cost me nearly $200; if the problem comes back, I can buy a decent external auto tuner for little more than that.

I had a similar problem with my Icom IC-746PRO. I sent it in, and the service tech could not duplicate the problem, and when I got it back, it worked just fine.  My guess is that it was a sticky relay that got unstuck with all the jostling during shipping.  My bill was about $170, but for that, I at least got them to fix a minor problem with the LCD backlight as well as install all of the factory updates.

I never even considered buying an external tuner instead of getting the internal tuner fixed, but this is a really good idea.  At Field Day, we used an LDG Z-11Pro  that plugged right into the IC-746PRO and was tuned by hitting the TUNE button on the radio.  Worked like a charm.  Universal Radio sells them for $170. They handle a wider SWR range, too, than the internal tuner on this Icom. If the internal tuner ever goes out again, I’m buying an LDG.

Your First HF Dipole

On the HamRadioHelpGroup mailing list, Tim, N9PUZ, pointed a link to the eHam article, “Your First HF Dipole.” As Tim points out, the article “describes a good technique for zeroing in on a low SWR,” Here’s that portion of the article:

  • Put the thing in the air as high as you can. Then find the frequency where the SWR is lowest. This might be at the bottom of the CW band or at the top of the phone portion. It doesn’t matter. RECORD that frequency.
  • Then take the actual length of the antenna (you wrote it down, remember?) and multiply it by the frequency (in MHz) of the lowest SWR. That number will be your new constant, to replace 468.
  • Divide the new constant by the frequency you want to have in the middle of your preferred range. This is the length the antenna should be. Now you need to adjust the one you have in the air to this length. You might find it’s easier to simply add or take away equal lengths on either side near the center insulator rather than on either end.
  • After doing this haul the antenna back up into position. It should now give you the lowest SWR at the desired frequency.

If for some reason you later want to trim an HF wire antenna (say, you decide to move to a different band segment), don’t waste your time cutting a half-inch at a whack. You can estimate how much to cut or add based on the band and how far you have to move it.

For example, compare 468/ 14.0 = 33.42 ft with 468 / 14.35 = 32.61 ft , so only about 10 inches to move the width of the entire band on 20 meters.
On 75/80 meters, the difference between the band extreme edges is better than sixteen feet.

Diana, KC2UHB, Does It Again

Diana, KC2UHB does it again, coming up with a roll-up yagi for satellite communication.

Who’d have thought that sewing would be an essential skill for homebrewers?

The Ultimate Stealth Antenna?

From the 2010-01-26 issue of NIST Tech Beat:

Engineered Metamaterials Enable Remarkably Small Antennas

NIST Z Antenna
This Z antenna tested at the National Institute of Standards and Technology is smaller than a standard antenna with comparable properties. Its high efficiency is derived from the “Z element” inside the square that acts as a metamaterial, greatly boosting the signal sent over the air. The square is 30 millimeters on a side. Credit: C. Holloway/NIST

In an advance that might interest Q-Branch, the gadget makers for James Bond, the National Institute of Standards and Technology (NIST) and partners from industry and academia have designed and tested experimental antennas that are highly efficient and yet a fraction of the size of standard antenna systems with comparable properties. The novel antennas may be useful in ever-shrinking and proliferating wireless systems such as emergency communications devices, micro-sensors and portable ground-penetrating radars to search for tunnels, caverns and other geophysical features.

NIST engineers are working with scientists from the University of Arizona (Tucson) and Boeing Research & Technology (Seattle, Wash.) to design antennas incorporating metamaterials—materials engineered with novel, often microscopic, structures to produce unusual properties. The new antennas radiate as much as 95 percent of an input radio signal and yet defy normal design parameters. Standard antennas need to be at least half the size of the signal wavelength to operate efficiently; at 300 MHz, for instance, an antenna would need to be half a meter long. The experimental antennas are as small as one-fiftieth of a wavelength and could shrink further.

In their latest prototype device,* the research team used a metal wire antenna printed on a small square of copper measuring less than 65 millimeters on a side. The antenna is wired to a signal source. Mounted on the back of the square is a “Z element” that acts as a metamaterial—a Z-shaped strip of copper with an inductor (a device that stores energy magnetically) in the center (see photo).

“The purpose of an antenna is to launch energy into free space,” explains NIST engineer Christopher Holloway, “But the problem with antennas that are very small compared to the wavelength is that most of the signal just gets reflected back to the source. The metamaterial makes the antenna behave as if it were much larger than it really is, because the antenna structure stores energy and re-radiates it.” Conventional antenna designs, Holloway says, achieve a similar effect by adding bulky “matching network” components to boost efficiency, but the metamaterial system can be made much smaller. Even more intriguing, Holloway says, “these metamaterials are much more ‘frequency agile.’ It’s possible we could tune them to work at any frequency we want, on the fly,” to a degree not possible with conventional designs.

The Z antennas were designed at the University of Arizona and fabricated and partially measured at Boeing Research & Technology. The power efficiency measurements were carried out at NIST laboratories in Boulder, Colo. The ongoing research is sponsored by the Defense Advanced Research Projects Agency.

* R.W. Ziolkowski, P. Jin, J.A. Nielsen, M.H. Tanielian and C.L. Holloway. Design and experimental verification of Z antennas at UHF frequencies. IEEE Antennas Wireless Propag. Lett., 2009 vol. 8, pp. 1329-1332.

Stuart Gets on the Air

After several months, we finally got Stuart, KD8LWR, on HF from his home. The first hurdle was deciding on what antenna to put up. This choice was complicated by two factors:

  • Stuart’s family lives in a relatively new subdivision carved out from a farm field, with absolutely no trees to hang an antenna from.
  • The homeowner’s association had some antenna restrictions.

Jack, Stuart’s father, met with the homeowner’s association and got them to agree to let him put up a trap vertical, and after some back and forth, we decided to put it towards the back of his lot near some pine trees. In that spot, it’s away from the house, and the pine trees hide it from plain view.

The antenna they purchased was a Hustler 4BTV, and we put it up Sunday afternoon. It took us about two and a half hours to construct the antenna, cut and lay the radials, and run the coax in a shallow trench from the antenna to the house. We started at 3 pm and finished just as it was getting dark. I was hoping that we wouldn’t have to do much in the way of tuning, as this would be pretty much impossible in the dark.

I used the dimensions called out in the instructions, and was kind of surprised to find that the resonant point on 40m was actually around 7150 kHz. The SWR at 7030 kHz was about 1.5:1, meaning that Stuart could work pretty much the entire CW portion of 40m. I didn’t get a chance to check the SWR on any of the other bands.

The rig Stuart’s using is a Kenwood TS-140 that had been donated to the museum. We connected the antenna to the rig, and it came to life. Unfortunately, the band had gone out by this time, and there was very little activity. We did copy a PA5 around 7026, and that was exciting, but there were very few stations on.

Actually, it didn’t matter. We couldn’t transmit anyway. It slipped my mind that the TS-140 didn’t have a built-in keyer, and I didn’t make a cable to connect Stuart’s old MFJ keyer to the rig. Transmitting would have to wait until Monday.

Monday evening, around 7:30, I returned with the cable. We tuned around a bit, but again the band had gone out, and we could hear only a very few weak stations. Stuart called CQ a couple of times, but without any success. I then suggested that I go home and we work a little ground wave.

It took me about twenty minutes to get home, and Stuart was waiting for me. We got coordinated using one of the local repeaters, and soon we were having our first CW QSO. After a nice 20-minute contact, it was time for Stuart to hit the sack, so we said 73.

I’m sure that will be the first of many contacts. I still need to get over there and tune up the antenna a bit more, but I think it’s going to work out very well. So, be listening for him, especially on 40m CW, and when you do contact him, tell him that you read all about it on this blog. :)

Sad News…and a Reminder

Sad news today from the ARRL website:

Three People Killed While Erecting Ham Antenna

At approximately 8:40 PM on Monday, October 12, a man, woman and their 15 year old son were killed while trying to erect a 50 foot vertical antenna at the home of the man’s mother, Barbara Tenn, KJ4KFF, in Palm Bay, Florida. The deceased were not licensed amateurs.

“It happened in an instant,” Palm Bay Fire Marshal Mike Couture said in a statement. “It is an unfortunate set of circumstances that led to the most tragic result.”

According to police reports, Melville Braham, 55, Anna Braham, 49, and their 15 year old son Anthony were putting up an antenna — Tenn’s second — at night when they lost control of the antenna and it crashed into nearby overhead power lines. The impact sent 13,000 volts of electricity through the pole the three were holding. A family friend, a 17 year old boy, was on the roof at the time of the accident. He and the couple’s daughter, who was in the house at the time, were not injured.

The mother was pronounced dead at the scene. When paramedics arrived, the father and son were not breathing; rescue crews immediately tried to resuscitate them. They were transported to a hospital where they later died.

Neighbor Jim Vallindingham told television station WFTV that he called 911 when he saw the fire in the back yard and then he ran over: “I had no idea it was electrical until we got over there and saw the three people laying on the ground. So I called 911 a second time to tell them there were casualties. You know, there were people on the ground. So [the 911 operator] told me that’s electric, you back away don’t touch anything.”

Couture said that night was not the best time to be attempting to put up an antenna. “It wasn’t the best time, meaning it was night time. Obviously, in darkness, and trying to do something like this and not being keenly aware of where the power line is in the backyard, [was not a good idea],” he said.

Neighbors said that Tenn, an ARRL member, used Amateur Radio to talk with her family in Jamaica. — Thanks to WFTV and Central Florida News 13 for the information

BE SAFE, PEOPLE!

Anyone Got a T-2?

Thirty or more years ago, I bought a random-wire tuner from a company called SST Electronics. I never did get it to work right back then, but a couple of years ago, I dug it out of the desk drawer and got it to tune a random wire on 80m. (See “The W3EDP Antenna” for more information).

A couple of weeks ago I was reading an old ham radio magazine, and lo and behold, I found an ad for the company. Not only that, they were advertising an SST T-2 Ultra Tuner, in addition to the T-1 (see below).

Now, I’d like to purchase a T-2 to complete my collection. Anyone got one?

More Sweet Tweets

Here are some more links to interesting Web pages I found by Twittering:

  • N3OX’s Remote Tuner Control. N3OX has added some servo motors and controls to a manual antenna tuner so that he can move it closer to the antenna, but still control it from inside the shack. Very inexpensive solution.
  • Band Plans for 900 MHz and Above. KB9MWR feels that the future of ham radio is above 900 MHz. I don’t know that I totally agree, but I do think we need to start thinking more about those bands. Give this a read.
  • Morse Code vs. Text Messaging. Chas Sprague, who’s not a ham, ruminates on how Morse Code could make text messaging more efficient. I wholeheartedly agree! Someone get this man his ham ticket.
  • Ham Logging as a Service. There’s been a lot of twittering about this KE9V blog post. I like the idea myself, and if I had more time, I might even take a crack at it. Anyone want to collaborate?
  • Planning a Digital ATV Station. After pondering a digital ATV station for the museum, I opted to go analog. If I’d seen this article first, I might have opted to stick it out and go digital.

Yet More Links

Here are more websites that I’ve come across that could be of interest to amateur radio operators:

  • MIT Open Courseware. Want to get an MIT education without moving to Cambridge or paying high tuition? Take courses online! Of course you won’t get an MIT degree, but I bet you learn a lot. One place you might start is 6.071 Introduction to Electronics.
  • W5LET’s Bare-Essentials Transmitter. 1968 was a simpler time. That’s the year this one-tube transmitter project was published in Electronics Illustrated. It’s articles like these that got me interested in ham radio. Find a 50C5 and build this rig.
  • W5GI’s Mystery Antenna. I found this antenna while looking for a design for an 80m antenna that would fit on my lot. I haven’t built this antenna yet, but it’s on my list of things to do.
  • Amateur Radio Special Events. I like working special events stations, both operating them and contacting them. Here’s a website devoted entirely to special event stations. For example, it lists the following taking place in November:
    • XE2BC – Nov 10 – XE2BC , founded in 1946, will celebrate the founding date on November 10th 2006
    • K6PV – Nov 12 -15 – mini IOTA DXpedition to Santa Catalina Island (NA-066) California
    • ARMAD – Nov 13 – Amateur Radio Golden Corral Military Appreciation Day
    • W6OI – Nov 25- 26 – 10 -10 International Club Station Special Event
  • Ridge Equipment Company. This company sells both new and used test equipment, including dummy loads and attenuators. The prices for the used gear looks pretty good.