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:
I even managed to do more than simply swap signal reports with the UK stations.
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.
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?
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.
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.
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.
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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
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:
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.
So, I thought I’d try working a couple of the state QSO parties today (VT, MN, DE).
Since the only antenna I have up right now is a 30m dipole, I figured I could use my antenna tuner and load it up on 20m. I was able to do that just fine, but I couldn’t hear any of the QSO parties. The only contest I could hear was the First Class Operators Club contest. Since I’m not a member of that elite group, I didn’t try to join in.
As I said, I was able to tune the dipole to work on 20m just fine, and even though I got on after 6 pm EST, I was able to make three contacts. One thing that strikes me about 20m vs. 30m is the level of activity. 30m seems to shut down as soon as the band gets a little shakey. I guess what few ops there are pull the plug real quick, and the band gets quiet real fast.
On 20m, however, one can still hear stations even after 30m gets quiet. I guess since there are more operators, there are just more possibilities of making contacts, even though signals start getting weak.
I guess I should put that 20m ground plane antenna back up and operate 20m more. There’s a tree in the front yard that I could use to hang it up, and maybe if I add a third leg to the ground plane, it will work even better than it did before.
Jack Twilley KC2ELS suggests the following Palm applications:
