Ham Radio Tip of the Day: Use WWV to check your rig’s calibration

There’s a very simple way to check the calibration of your rig, using WWV and a laptop computer running a digital modes program. First, connect the rig audio to the computer. At home, I connect the line output of my IC-746PRO to the mic input of my laptop. At WA2HOM, we use a SignaLink USB to connect the rig’s line output to our desktop computer.

Next, set your radio to one of the WWV frequencies. Here in Michigan, we receive WWV best on 10 MHz, so that’s the frequency that I use. On my IC-746PRO, I set the receive frequency to 10.000.00 MHz, using the keypad.

Now, fire up the digital modes program and observe the waterfall display on the laptop. WWV broadcasts standard frequency audio tones that alternate during most minutes of the hour. Most minutes feature a 500 Hz audio tone (minutes 4, 6, 12, 16, 20, 22, 24, 26, 28, 32, 34, 36, 38, 40, 42, 52, 54, 56, 58) or 600 Hz audio tone (minutes 1, 3, 5, 7, 11, 13, 17, 19, 21, 23, 25, 27, 31, 33, 35, 37, 39, 41, 53, 55, 57), but note that during some minutes, there is no audio tone.

This tone should be easily discernible on the waterfall display, and the closer it is to 500 Hz or 600 Hz, depending on which tone is being broadcast, the closer your rig is to being properly calibrated. I do this every month or so, just to make sure that my radio hasn’t drifted.

For more information on the WWV transmissions, go to Information Transmitted by WWV and WWVH.

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From the trade magazines, impedance matching, EMI basics, open-source hardware

elelctronic-design-logoBack to Basics: Impedance Matching. electronic design editor (and amateur radio operator) Louis Frenzel is the author of this short e-book on impedance matching. Note: this e-book was intended for engineers and does use a fair amount of math, but nothing you can’t figure out if you work at it.

EMI Basics. This article  comes from the book Signal Integrity Issues and Printed Circuit Board Design by Douglas Brooks. I like the discussion of how twisted pair wire helps prevent radiation.

Interview With SparkFun’s Director Of Engineering. Peter Dokter is director of engineering for SparkFun, one of the major suppliers of open source hardware. SparkFun designs and sells things useful and interesting to the aspiring electronics tinkerer, including microcontroller boards, Bluetooth, GPS, Wi-Fi, LCD displays, e-textiles components, robots and robotic parts, motors, motor drivers, buttons and switches, tools, and books.

From my Twitter feed: software-defined scanner, TAPR in Seattle, the art of electronics

n0rc
How to get started using the #rtlsdr as a scanner for as little as $19http://t.co/VK3qKdpMJS #sdr #hamr

This looks like fun…..Dan

 

HamBeat1
Seattle Will Host the 32nd Digital Communications Conference:http://t.co/0xGJUpjw1C #hamradio #hamr

I should have gone last year, when it was a lot closer……Dan

 

o0ToTOm0o
The Art of Electronics – Horowitz & Hillhttp://t.co/4p2rYYfcvV

A classic! Get it. It’s free……Dan

From my inbox: CQ Burger King, BPL, solderless PL-259

Amateur radio plays a big part in this new Burger King ad.

 

FCC Denies ARRL BPL Petition. As this commentary from TV Technology notes, the FCC denied the ARRL’s that BPL systems include full time notching of amateur radio frequencies and an increase in the required notch depth from 25 dB to 35 dB. They also say, “While the Second MO&O isn’t good news for amateur radio operators, utilities seem to have lost their interest in using BPL to provide residential Internet access…and smart meters so it may have little real impact.” Let’s hope it stays that way.

Solderless PL-259. On the AMRAD mailing list, one ham writes:

Shakespeare has been in the marine antenna business since shortly before the discovery of oceans and they have a couple of bits of kit which you might consider for your ARES or Field Day bug-out box. They make a PL259 and a coax cable spice which go together with nothing but a knife sharp enough to cut the plastics and a pair of pliers. I wouldn’t try running the legal limit through these (the coax they fit wouldn’t like it either) but i have used the PL259 for up to 100-watt service and they have performed admirably.

They are kind of expensive at around $15 a pop, but they do look like quality parts and that they’d work pretty good in a pinch.

From the NIST Tech Beat: emcomm, generators

Here are a couple of items that may be of interest to amateur radio operators from the April 17 issue of the NIST Tech Beat:

tb20130417-nytest_originalNIST Tests in New York City Suggest How to Improve Emergency Radio Communications
Radio communications can be unreliable in underground tunnels and other large, complicated structures, posing a safety hazard for emergency responders. New tests of wireless emergency safety equipment by NIST have defined the challenges more precisely and suggest how emergency communications might be improved.

Prototype Generators Emit Much Less Carbon Monoxide, NIST Finds
Portable electric generators retrofitted with off-the-shelf hardware by the University of Alabama emitted significantly lower levels of carbon monoxide, according to the results of tests conducted by NIST for the U.S. Consumer Product Safety Commission.

Deciphering schematics like solving a puzzle

My brother, Mike, goes to estate sales. (He also blogs about estate sales, following a fine family tradition.) He finds all kinds of cool stuff at these sales, but for the past year or so, he’s been most keen on acquiring pinball machines. He now has a shuffle bowling machine and a Merry Go Round pinball machine.

Mike is an accountant, and because he had very little technical training, he asked if I would help him troubleshooting the electrical parts of the machine. Being a former pinball player myself, I said sure. It’s been a lot of fun. Deciphering the schematics—and, fortunately, the schematics for most of these machines are readily available—is like solving a puzzle.

The Merry Go Round machine is a good example. Below, is the schematic of the primary circuit of the machine. (Click on the image to get a larger version of it.)

Figuring out how this circuit is supposed to work was a lot of fun.

Figuring out how this circuit is supposed to work was a lot of fun. (Click on the image to get a larger version.)

Shortly after he bought this machine and got it down in his basement, he called me and said, “It doesn’t work. I plug it in and nothing. No lights. Nothing.” I told him to take a picture of the schematic with his camera and send it to me. I got an email with the image above minutes later. Now that we were literally working off the same page, we could figure out what was wrong.

One of the first things I noticed is that the component symbols are drawn a little differently than the symbols we use in electronics. This can be seen on the bottom line of the schematic. The switches almost look like capacitors.

Another difference is that both mechanical switches and relay contacts are drawn the same way. The switches are given a name, such as “ANTI-CHEAT SW,” while the relay contacts are labelled with a single letter. The relay coils are also labelled with a letter making it easy to determine what relay coil closes which contacts.

Once I figured that out, I started decoding the circuit logic. Unlike some machines, this one does not have an on-off switch. After staring at the schematic for several minutes, I figured out that the key was the COIN CHUTE switch. This switch is supposed to be activated when someone puts in a dime. Closing that switch allows current to flow through the K relay, which closes the K contacts. One of the K contacts applies power to the transformer primary.

I had my brother plug in the machine, then very carefully close the COIN CHUTE switch with a screwdriver. This was necessary because the coin mechanism wasn’t working right. Unfortunately, nothing happened when he did this.

Next, I had him check the switches on the very bottom of the schematic: ANTI-CHEAT SW, SHUTOFF SW, and the BOUNCE SW. As you can see, all of these have to be closed for power to get to the transformer primary. I told him to unplug the machine and then use his multimeter to measure the continuity between the switch terminals. After a discussion of what range to set his multimeter to, how the meter measures resistance, and why unplugging the machine was necessary, he did so.

At first, he reported that all three switches were closed. We were doing this over the phone, so I had to take his word for it, but that just didn’t seem right. If they were all closed, something should have happened.

I thought it might be possible that the K relay coil was open or maybe shorted, so I had him check its resistance. It measured about 400 ohms. I then had him measure the resistance of the E coil. That also measured about 400 ohms. Since the both measured about the same, I guessed that they were probably OK.

So, I had him check the switches again. This time, he found that the BOUNCE SW mechanism seemed stuck open. He fiddled around with it, and when he thought he’d gotten it closed, he plugged in the machine again and tried the COIN CHUTE switch again. Success! Lights came on and the motor started turning.

He’s got a lot more work to do before we can start playing the game. Bumpers need to be replaced and the scoring wheels need to be cleaned and lubricated, but we learned a lot about the machine with this exercise. It won’t be long before we’re playing pinball.

From my Twitter feed: HF receivers, voltage reference, FDIM

ke9v
A History of HF Receivers | Smoke Curlshttp://t.co/A2uHc38mic #hamr

 

dangerousproto
Erl’s voltage referencehttp://t.co/X0MOESc8BO

I need to build one of these……Dan

 

qrparciFDIM 2013 (Dayton) – Full seminar schedule now online http://t.co/9eWdTI0FEx #hamr#qrp #hamvention

I’ll be attending FDIM. If you see me, say hi….Dan

From my Twitter feed: scholarships, testing power supplies, MT63

Lots of cool things in my Twitter feed this morning…….Dan

k9hi
Apr. 15 deadline is fast approaching for FAR scholarship applications. Seehttp://t.co/8eCHFvTM1x #hamr

dangerousproto
How to measure stability when testing power supplies http://t.co/WkzW6ZXMKD

hamradiopodcast
VOA Radiogram features MT63http://t.co/gslMp6qukr

You need a digital multimeter

I’ve decided that my next book is going to be about multimeters. Here’s a draft of the first chapter…Dan

Digital multimeters, or DMMs, are the most commonly-used test instruments by electronics engineers, technicians, and hobbyists to design, build, and troubleshoot electronic circuits. If you work with electronics or electrical circuits, either as a professional or as a hobbyist, you need a digital multimeter. Without one, it’s almost impossible to adjust or troubleshoot circuits.

Let me give you an example. About a year ago, my brother, Michael, decided that he was going to purchase a very-used shuffle bowling machine at an estate sale. This is the kind of coin-operated machine that you would often in bars. Put in a dime and it would allow you to “bowl” a game.

The unit he purchased was built in the late 1950s. Needless to say, it needed a lot of work. Before he actually paid for it, Michael asked me if I would help him fix it, and I said sure. It looked like it would be a lot of fun to get it running again.

The first thing that I advised him to do-once he got the machine home-was to buy a digital multimeter. With the digital multimeter, he was able to:

  • Check the voltage across the transformer secondary windings to ensure that the transformer was still good.
  • Check the continuity of the many solenoids in the machine to ensure that they were not shorted or open.
  • Check the switches to make sure that they operated properly.
  • Check the continuity of the wires in the cables connecting all the switches, solenoids, and indicators.
  • And make many other measurements.

Without the digital multimeter, it would have been next to impossible to get the machine working again.

If you’re an amateur radio operator, you’ll need a multimeter to measure the output of your power supply and set it properly. You’ll need it to measure the resistance of the resistor that you’re going to insert in the printed circuit board of the kit you’re building. You’re going to need it to make sure that you haven’t shorted out your coax after you’ve installed a PL-259 connector on it. I have used mine for all of these measurements and more.

If you’re a homeowner, you can use a multimeter to check that the voltage present at an AC wall socket is really 117 VAC. You can also use it to make sure that the socket is wired properly.  You can also use it to tell if a switch is working properly or if a circuit is wired properly.

What is a digital multimeter?
Simply put, a DMM is a test instrument that allows the user to measure voltage, current, and resistance, the three primary characteristics of an electrical circuit. While some DMMs may have other functions, measuring voltage–both direct current (DC) voltage and alternating current (AC) voltage, AC and DC current, and resistance are the most basic.

It’s called a “digital” multimeter because it uses digital electronics technology, rather than analog electronics technology to make measurements. Older “analog” multimeters used an electro-mechanical meter, like the one shown below, to indicate the value of the voltage, current, or resistance being measured. To make the measurement, you had to note how far the meter’s needle had deflected and then read the value from a scale printed on the face of the meter. A digital multimeter, on the other hand, displays a number on its LCD or LED display.

The venerable Simpson 260 analog multimeter uses an electromechanical meter to read out measured values

The venerable Simpson 260 analog multimeter uses an electromechanical meter to read out measured values

The difference between the two technologies is very similar to the difference between mechanical clocks and digital clocks. With a mechanical clock or watch, you have to note the positions of the two hands and then estimate the actual time. With a digital clock, you simply read the numbers. Both tell you the time, though.

While many old-timers swear by their analog meters, and while there are a few applications for which an analog meter is preferable to a digital meter, if you’re in the market for a multimeter, you want to buy a digital one. One reason for this is that most analog meters—at least ones that are any good—are really expensive. This generally makes instruments made with an analog meter more expensive than a digital multimeter that offers similar performance.

A digital multimeter will open up the world of electricity and electronics to you. With a digital multimeter, you’ll be able to make measurements that will show you how electrical and electronic circuits really work. And with that knowledge, you’ll save money as a homeowner and have more fun as an electronics hobbyist.

On the air this weekend at WA2HOM

WA2HOM is our club station at the Ann Arbor Hands-On Museum. I go down there nearly every weekend and operate for anywhere from two to eight hours. This weekend, I had a lot of fun down there.

This photo, from the Boy Scouts of America website, shows one Cub Scout sending code to another.

Late last week, I was contacted by a woman who was a Cub Scout pack leader, asking if she could bring some Scouts by. Silly question. Of course, she could! We arranged to meet around 1:45 on Saturday. Well, right on time, she arrived with three Cub Scouts in tow.

Fortunately, I had just made contact with Jim, K0JIM, and he had a really solid signal here in Ann Arbor. That’s important because it’s sometimes difficult for inexperienced operators to hear a weak signal or one that’s accompanied by a lot of noise. When signals are weak or hard to copy for any reason, the kids get frustrated.

We were doubly fortunate in that Jim was just great with the kids. He asked each their name and got them to tell him a little bit about themselves. And, none of the kids were mike-shy, so it was a good experience for everyone involved. In addition to having them talk on the air, I took them over to our Morse Code display and showed them how to send their names in Morse Code.

I really hadn’t planned to go down on Sunday, but after doing some things around the house, I decided to zip down there about 2:30 pm to check into the Rotarians on Amateur Radio net. It’s so much easier to do from down at the museum because of the beam antenna. I didn’t hear a peep on the net frequency (14287 kHz) at either 3 pm or 4 pm (2000Z, which is the time listed on the ROAR website), though, so I’m not sure what’s going on there.

When I’m at the museum, I’m usually also tweeting. (I’m @kb6nu on Twitter.) I tweeted that 20m sounded kind of quiet, and got a reply from @hamradioireland, EI2KC, suggesting that we give it a try. After agreeing on a frequency, I pointed the beam northeast and gave him a call. Unfortunately, the propagation didn’t cooperate, and we could barely hear one another. Even so, it was still pretty cool using Twitter to arrange a DX QSO.

Tuning around after my short QSO with EI2KC, I found a couple of interesting nets. The first was the Collins Collectors Association Net on 14263 kHz. I could really only hear the net control station, but it sounded as though everyone checking in was running some kind of Collins gear. It was interesting to listen to, but not being a Collins operator, I didn’t check in.

Around 4 pm, I started looking for the ROAR net again. I never did find that net, but I did find the Heathkit Net on 14293 kHz. According to the Web page Heathkit Resources, the net starts at 2030Z, but I’m guessing that it really started at 1930Z.

Since I have a bunch of Heathkits—several that I still use regularly—I did check into this net. They’re a great group of guys, and I will definitely be checking into this net again. Who knows? It may even spur me to get my HW-101 back on the air.