Contesting and Band Choice

After my mediocre performance in the Fists Sprint a couple of weeks ago, which I blamed on my antenna, I decided that I’d better put up my 20m ground plan antenna again. So, this morning, just before the North Carolina QSO Party was to start, I threw a rope over a tree branch in the front yard and hauled up the ground plane. I spread out the two radials, snaked the coax into the house, and I was in business. The SWR measured 1.2:1.

I tuned to 14.040 and worked a couple of stations and began to think that I was going to do OK. That quickly came to an end, however. The band must have changed, because stations that were truly coming in 599 suddenly dropped way down in strength. In fact, I was hearing European stations calling the NC stations that were stronger here than the NC stations. I even tuned down to 14.033 and worked one of the Germans just for the heck of it.

Apparently, the radiation angle of the ground plane was too low and skipping right over North Carolina. I probably should have gotten on 40m, but I still don’t have an antenna for that band. I guess that should be my next project. The best band to work NC at this point might actually be 30m, but by gentleman’s agreement, there’s no contesting on the 30m band.

Oh, well. The contest runs to 10 pm tonight, so perhaps I’ll get back on a little later and see if anything’s cooking.

Update 5-9-04:
Despite my mediocre performance (7 total QSOs, 155 total points), I actually had the highest score in the state of Michigan. (It was probably the only score from the state of Michigan.) For my efforts, I received a certificate, noting my first place finish.

Use your antenna analyzer to test ferrite-bead chokes

From Tim, KT8K…

Here’s a test procedure to test the ferrite-bead chokes you buy at hamfests or Radio Shack.

Ferrite chokes are widely used to reduce or supporess RFI in electronic and electrical equipment. Many computer cables, in general, have lumps in them which are built-in ferrite beads. Of the many split-bead ferrite choke types, mix 43 is generally accepted as the best choice for stopping RF from getting through your power and audio cables. Other mixes are not much help in amateur radio applications.

The cool thing about this technique, I think, is that now I can pop some batteries into my MFJ259, sling it over my shoulder, and actually evaluate the chokes I consider buying at swaps before I spend my money. In the past I just bought them and installed them and hoped that they were helping. Using this procedure I can be sure of what I’m getting.

The following procedure is adapted from and courtesy of Alan Applegate, K0BG. Read this article for more details.

To test ferrite beads, you will need an antenna analyzer, such as the MFJ-259, and enough hookup wire–size 22 is ideal–to make 5 passes through the bead plus enough to connect the ends to the analyzer.

Test Procedure

  1. Wind 5 turns of 22 ga. hookup wire through the bead to be tested and connect the ends to the center and shield connection on the antenna analyzer.
  2. Set the frequency to 2 Mhz, and measure the reactance. If it is mix 43, the inductive reactance will be approximately 500 ohms.
  3. Push the mode button three times to bring up the inductance menu. If your bead was made with mix 43, the inductance will be about 40 μH. A lower reading may indicate that the ferrite is not mix 43, and it may not work properly. If the reading is higher, that’s fine to a point, but double these figures may indicate mix 77 (ui=1800), which is better suited for 160-meter suppression.

Note: the 259B hasn’t enough range to check mix 43 at much more than 2.5 Mhz unless you reduce the number of turns.

A note from KB6NU…

I just ran down to the shack, and pulled out my Autek VA1 Vector Analyzer to perform this test. The results were quite interesting. Testing four of the five ferrite bead chokes that Tim KT8K bought for me at a hamfest about a year ago, I got the following results:

Bead Inductance (μH) Reactance (Ω)
1 34.5 432
2 35.6 448
3 37.1 465
4 34.5 430

These values aren’t too far off, so I’d say I got a decent batch.

Contest Conditions on 30m

I just finished working the 30 m band for the last hour, and it was almost like working the DX contest over the weekend. I made eight contacts, all but one a DX contact, including:

  • 2 UK stations–G0VDI and G3DDA–both of whom responded to my CQ,
  • HA9RT,
  • F6EVN (up in the Pyrenees),
  • UT5JAJ (who was booming in),
  • EA5/DH5KAW (boy, isn’t that a handful to send!), and
  • W4AZZ, my only US contact tonight

I even managed to do more than simply swap signal reports with the UK stations.

More than just an antenna analyzer

On the Elecraft mailing list, there’s been a flurry of messages recently about LCR meters. One of the units touted was a unit from a company called Almost All Digital Electronics. They have both a kit version ($100) and an assembled version ($130). A couple of the guys even bought and built it.

I chimed in with the opinion that instead of buying yet another meter, that they should just buy an antenna analyzer to make those measurements. My analyzer can measure inductance and capacitance directly, and do so at any frequency up to 35 MHz. It may not be quite as accurate as the LCR meter, but my guess is that it’s plenty accurate for amateur use. And to top it off, I get to use it to analyze my antennas!

One of the non-conventional ways that I use the antenna analyzer is to demonstate the principles of reactance and impedance to my General class students. First, I measure the reactance of a coil that I’ve had around the shack for ages (at one time, I used it as a loading coil coil for a vertical antenna). I show how the reactance increases with frequency, then record the reactance at 6 MHz.

Next, I measure the resistance of a 150-ohm precision resistor that came with my analyzer. Then, I calculate the impedance with the equation Z = sqrt(XL**2 + R**2).

I then connect the resistor in series with the coil and measured the impedance. Surprisingly (or, not so surprising, actually) the measured impedance is almost exactly what I calculate.

Actually, my analzyer–the Autek VA1–is not an antenna analyzer at all. It’s called a vector analyzer. Most of the high-end antenna analyzers can make these kinds of measurements. They can also be used as low-level RF signal generators. So, while they’re most useful at analyzing antenna parameters, they can be used for more than just that.

 

Emerging Potential

In the March issue of World Radio, Alan Pickering, KJ9N, did a little speculating on the state of the Internet and why now might be a good time for ham radio folks to start recruiting young people, who have seemingly lost interest in ham radio in favor of the Internet. He says, that as far as the Internet is concerned, the bloom may be off the rose. The reason: SPAM.

He conjectures that now might be a good time to recruit young people so that they can have truly unfettered communications. I thought about this for a bit, and came up with this reply:

I just read your March column in World Radio. I must say that I like these ideas a lot! Now, what someone needs to do is develop a handheld with a small LCD screen that will allow instant messaging. Another idea would be to develop a little card like the wireless networking card that you can plug into a laptop, but instead of talking to wireless LANs, it communicates on VHF through a repeater somewhere. Maybe this is just the application that all those little-used 220 MHz repeaters out there are waiting for.

It does seem a bit far-fetched, but who knows?

Yet another episode in the antenna tuner saga

As I mentioned back in December, I’m now finally using the MFJ 941D VersaTuner II antenna tuner I bought many moons ago. At the time, I also noted that the metering wasn’t working. In no switch position, could I get the meter to move at all.

Well, about a week ago, I began to notice that every once in a while the meter would indicate some forward power. This activity usually lasted for only a single transmission, and on the following transmission, I’d again get nothing. Problems like this are usually just bad connections, so having a little time on my hands yesterday, I decided to pull off the cover and see if I could find the bad connection.

The first thing I noticed is that it would be an awful lot of work to actually get at the connections, much less replace a component. The circuit board with the switching and metering circuit is mounted on four standoffs to the bottom of the box, and all of the traces are on the bottom of the board. To get at those traces, I would, at minimum, have to unsolder the wires connected to the meter and remove the knobs from two of the front panel controls. Then I might be able to swing it up so that I could get at the bottom of the board, but that would still be difficult because of all the wires that run to the board from the coax connectors on the back panel and the coil and capacitors of the tuning circuit.

While I was mullling this over, I did a visual inspection of all the connections I could see. They all seemed to be good solder joints, so I rule them out as the problem. One thing I did notice is that one of the capacitors was mounted very poorly. One leg of the capacitor went straight down into one hole, while the other leg was bent. couldn’t see the lead on the straight leg, making me think that this may be the bad connection. Perhaps the coating on the leg prevented a good solder joint to that leg. While it may have made a tenuous connection at first, the shock and vibration experience by the tuner while in use and through several moves finally caused that connection to come loose.

Since I really didn’t want to hassle with disassembling the whole thing just to get at the board, I decided to wiggle all of the components to see if I was right about the loose connection. What do you know? It worked! Now, the meter is reading as it should. That is to say, it swings up when I transmit and the switches are set to read forward power. I have no idea, of course, how well calibrated the meter is. I suspect that it’s not all that accurate.

Since what I did was kind of kludgey, I expect that the meter will quit working again soon. At that point, I really will have to take the thing apart and resolder the connections. Uggggh.

A Couple New Countries

After sitting at the rig for nearly four hours working the Fists Winter Sprint, and achieving a solidly mediocre results, you’d think that I’d have had enough ham radio for one day. Well, you’d be wrong.

My wife has a cold and didn’t feel like going anywhere tonight. In fact, she just wanted to sleep. So, after dinner, I went back down to the shack. I tuned the antenna back to 30m, and tuned around a little. When I didn’t hear anything, I set the rig to 10.109 and then started playing with the computer log from the contest I worked earlier.

As I was playing with the log, ZD8R (Ascension Island) called CQ on that very frequency! How’s that for being in the right place at the right time? I was the first one to contact him before the hoard of DX spotters got on frequency. He gave me a nice 579 report, too. After our QSO, chaos ensued.

A little bit later, I heard V51AS (Namibia) working stations down around 10.105. There were a few stations on frequency, but nothing like the pileup for ZD8R. He even resorted to calling CQ a few times. I don’t know why, but I wasn’t in any real hurry to work him, but eventually, I jumped in there and called and exchanged 559 reports with him.

So, while the results may have been disappointing on 20m, the antenna sure seems to be working quite well on 30m.

A Disappointing Result

Contest are good tests, not only for one’s operating skills, but also for one’s equipment. Witness my experience yesterday operating the Fists Winter Sprint.

Last winter, using homebrew 20m ground plane, I scored 5,300 points. This winter, using a 30m dipole tuned to 20m, I scored barely 3,300 points. This was a very disappointing result, considering that band conditions were very good yesterday.

The only thing that I can think of that would make such a big difference is the antenna. I was going to put up the 20m grounnd plane, but got lazy. I’d tuned up the 30m dipole on 20m the weekend earlier and made some contacts with it, and thought that it would do for the contest. Unfortunately, that turned out not to be the case.
Several times I called stations in the S4-S5 range, and they either could not hear me or I wasn’t strong enough to complete the contact. I also tried several times to camp on a frequency and call CQ on it, but was mostly unsuccessful in getting anyone to respond to my call. My guess is that I was 2-3 S units weaker than stations I contacted. I can see that I’m going to have to get that 20m ground plane back up before the next contest.

One bright spot was the N3FJP logging software I used. It worked very nicely during the contest, and it was a snap to produce the text file needed to file the log. One thing I wish it would do is export in Cabrillo format, but the Fists guy seems happy enough to accept the text file. I didn’t try using the CW output feature, but next contest, I’m going to hook that up and try it out. I want it all to be working by the Michigan QSO Party, so that when Field Day rolls around, it will work like a charm.

Free Schematic Capture Programs

My friend and former boss, Jon Titus KZ1G, sent me this:

Fellow techies,

When it comes time to draw schematic diagrams, take a look at DesignWorks Lite, a nice shareware version of the Capilano Computing professional DesignWorks software. You can use a free version for 30 days, or register for $40 and have unlimited use, plus access to new symbols and devices. It took me an hour or so of practice and fooling around, but I found it easy to master the software, which Capilano supplies for Windows or Mac OSs.

I particularly like the ability to change the attributes of devices. I can hide IC pin numbers, re-label gates, select generic parts, etc. But if I want an SN74ALS373 buffer, I can find one, with all of the pins called out. I can also flip, rotate, and reflect the diagrams to make sense for my layout. Connections “rubber band, so when I move a device, the connections move, too. I’ve tried Visio, but because it’s a drawing package, it lacks the EE look and feel of DesignWorks lite.

Here’s another recommendation for schematic drawing by my friend Martin Rowe. He writes:

I’ve always believed that what engineers most want to see in an engineering magazine are schematics and source code. This morning, I found a little schematic-capture program that you can download for free. It’s called TinyCAD. It does more the just drawings, but that’s all I’ll even need.

The user interface could use some simplification. Finding circuit symbols could be easier but I was able to get started in just a few minutes. Cost: Free. Download size: about 4.5 MB.

Update 10/7/04
From KE0X via the Elecraft mailing list:

I just found Eagle Version 4.13 which is available FREE for non commercial use at their website. I know nothing about these programs but I was using it in 5 minutes and made a template for a PCB in two days. Best of all you can print either layer and make your own PCB (ala laser masking, etc.) and not have to get it made from the supplier of the “proprietary” software that wont even let you print it. Yet, this program is sophisticated enough to make 8 layer boards….Rich, KE0X

The IC735 CI-V Interface

Every once in a while, I get the urge to build a computer interface for my IC-735. This isn’t as easy as it sounds as the Icom CI-V interface is not a standard RS-232 type interface. The signal levels are TTL-level signals and it’s a two-wire interface.

The last time I got the urge, I did a web search and came up with the following:

  • The Icom CI-V Interface. This is a complete online manual to the interface and the software driving it. The page on CI-V level converters has links to many different circuits, including a relatively complicated one using the MAX232 chip.
  • G3VGR Icom CI-V Interface. This is a nice little circuit using a couple of 2N2222s, two diodes, and four resistors.
  • THE ICOM CI-V COMPUTER INTERFACE. This is an article written in 1986 describing the CI-V interface. It not only describes the physical interface, but the command set as well. One thing I didn’t know–the IC-735 was the first rig to use this interface.
  • Ham Radio Controller Programs. This page contains links to a bunch of rig control programs and information, not solely for the IC-735.
  • 801SCAN. 801SCAN is actually a control program for the R7000, R7100 or R9000 receivers, but this page also has a circuit for a RS-232 to CI-V interface. This circuit uses a 74HC04 IC. Do not try using a 7404 in place of the 74HC04. Also, I would advise against using his construction technique, to wit, “Chop the unused pins off of the 74HC04 and glue it to one side of the DB-25 shell with super-glue…” This is NOT good amateur practice :) .
  • CI-V Icom/PC Interface OK1DUO. This circuit uses a MC145407 IC, which I’ve never heard of. It also requires a couple of zener diodes. It’s certainly much more complicated than the G3VGR circuit above.
  • Icom CI-V Interface Design by K4PWO.This design uses a MAX233 RS-232 interface IC and a 78L05 voltage regulator. There is also a sample PC board design. It’s a nice design, but I don’t think it will fit in a DB9 shell.

It’s odd that I didn’t find any that use optoisolators. I’d think that doing this with optoisolators would be ideal. I guess the problem is that the rig doesn’t supply any power since it’s only a two wire interface (signal and ground). So, even if you use an opto, you won’t be isolated because the interface is supplying the voltage.

Of course, I could go out and buy an interface, but I think any self-respecting ham should build something like this that is so simple.