Discovery Science Center – Advanced Ham Radio on Display at the Meet the Makers Event

Signage at The Discovery Cube announces the Meet the Makers Event
Dennis Kidder (W6DQ), Walter Clark and I demonstrated our Maker Faire ham radio projects at the Discovery Cube in Santa Ana on June 29 and 30, 2013. We used my TinyTrak APRS beacon to indicate our location during the event. In case the plot is removed or expires, here is an image of the map showing our location. KH6WZ is indicated by the eye icon near the Interstate 5 freeway in Santa Ana.

This is a screen capture showing the KH6WZ APRS beacon data from the Discovery Science Center – Meet the Makers event.
This was a great opportunity to expose people to today’s technology Amateur Radio, and continued along my Maker Faire theme, “Not Your Grandpa’s Ham Radio.”
Dennis brought his dual band 10 GHz and 24 GHz transverter, controlled and interfaced to his software-defined radio (SDR).
Walt brought his polarization demonstration units, which helped people visualize how radio signals propagate and change as they travel through the air. Here’s how Walt explains his demos:
Two demonstrations show the structure of radio waves – in this case microwaves.
One
The structure of a radio wave in angle around the direction of travel: This is called polarization. A spinning bargraph that has a receiving antenna that also spins will reveal the way radio waves “look” to a receiving antenna. The lesson here is that the receiving and transmitting antennas have to be oriented to the same angle.
Two
The structure of a radio wave along the direction of travel: When a receiver is arranged to look exactly in [or along] the direction the radio waves are going out, reflections can be measured; just like in radar. The reflection off of the hand or the chest of a person causes the speaker to be loud or quiet depending on the exact position. It cycles from loud to quiet every 1.5 cm whether inches or many feet away. The lesson here is that with this equipment, you can picture in your mind the wavelength and especially note that the wavelength is the same no matter how far the radio wave travels.
We did not establish any goals for this event, but there were several memorable visitors to our little table display, including teachers, Maker Faire participants, some current and ex-ham radio operators, many engineers and retired engineers as well as engineering students.
This “Meet the Makers” event was a double treat for me, since this was the first time I visited the Science Center, and I had a blast talking about the new technologies being used by today’s ham radio enthusiasts.
Here are some pictures of this event . . .
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An R/C R2D2 makes an appearance at the Meet the Makers event at the Discovery Science Center.
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The 24-inch dish antenna makes a great stand for signage.
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The KH6WZ APRS beacon display at the Meet the Makers event.
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Dennis W6DQ, brought his software defined radio with 10 GHz and 24 GHz transverter to our exhibit.
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Walt brought several fascinating displays to illustrate radio wave propagation.
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Dennis explaining the radio wave demonstration to our target audience: kids.
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Great shot of Walt explaining radio wave propagation to some visitors.
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The Science of Hockey at the Discovery Science Center
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A close-up of one of Walt’s displays
Acknowledgements
Thanks to Bequi Howarth, of the Orange County Mini Maker Faire, who introduced us to the Discovery Science Center.
Links to More Information
Byonics (TinyTrak APRS and Weather Units)
Discovery Science Center, Santa Ana, CA
Orange County Mini Maker Faire, University of California, Irvine (UCI)
Maker Faire
Make: Magazine
American Radio Relay League (ARRL)
CQ Magazine
San Bernardino Microwave Society (SBMS)
Wayne Yoshida LinkedIn Profile

APRS display of the KH6WZ-5 location beacon at the 2013 OC Mini Maker Faire at UCI. Notice the beacon message at the top of the screen capture includes the URL of the event – a great publicity tool!
This past weekend, the second OC Mini Maker Faire happened. And it just so happens to be the second running of my ham radio demonstration called, “Not Your Grandpa’s Ham Radio (2)!” This is my continuing mission to remind people of two things:
First, “The Maker Movement” is nothing new, Amateur Radio operators have been doing this for a almost a century, and nearly 2 million people worldwide are involved in ham radio in some way.
Second, Ham radio is not necessarily an old man’s hobby where weird guys talk to strangers from garages and basements. We are skilled wireless communicators and use today’s technology, from GPS and microprocessors to lasers and microwave frequency linking.
This time I added static and working displays of my various APRS beacons (KH6WZ, KH6WZ-5, and others). I programmed the OC Mini Maker Faire’s URL to the beacon message so people can take a look at what was happening – an excellent publicity tool!
I also planned on making some 10 GHz contacts with my rig, since this was also the same weekend as the ARRL 10 GHz and Up Contest. The transverter covers were removed so people can see the system’s guts.
Based on previous experience at the Discovery Science Center “Meet the Makers” event, I demonstrated radio wave polarization- horizontal vs vertical – with my rig and the microwave strength meter.
Since I had plenty of space, I shared my booth with a company that makes interesting computer and microprocessor related items. This may sound trivial, until you realize this company is run by these three young guys . . .

Huxley, Max and Ethan showing one of their products called the SmartPac.
There seemed to be more people at this Faire, probably since not too many other events were happening nearby. The 405/605/22 freeway closure did not affect the MF, since it started after the event ended.
More than a dozen hams – either active or at least licensed – stopped by to visit. We talked about this event as well as the Bay Area Maker Faire, and what ham radio activities we are involved with.
One more thing: I met several guys from the San Diego area – they are finalizing the plans to have a Mini Maker Faire in the San Diego area – this is great news. Stay tuned and I will announce an update as soon as I hear something from the committee!
Here are some pictures from the event. I am already thinking of building some new displays for next year.
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The 24-inch M/A-COM dish with the KH6WZ logo makes a pretty decent sign for the booth, eh?
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The KH6WZ 10 GHz transmitter-receiver unit on display at the Orange County Mini Maker Faire on the UCI campus
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KH6WZ horn antenna and microwave field strength meter at the OC Mini Maker Faire 2013
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The KH6WZ APRS beacon (unit 1) at the OC Mini Maker Faire 2013. This was a static display unit to show components and construction.
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KH6WZ-5 APRS beacon – active and sending position data at the 2013 OC Mini Maker Faire at UCI. The beacon message included the Faire’s URL.
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This familiar unit makes an appearance at the Maker Faire. . .
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The robot “Titan” was a crowd pleaser – it throws flying discs and comes to you for a refill.
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Track Roamer robot at the OC Mini Maker Faire. Notice the Nerf gun. When you come to next year’s event, remember to wear a red shirt.
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One of the “roving displays” at the OC Mini Maker Faire 2013.
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Some ham visitors at the Orange County Mini Maker Faire 2013: Haliey, Michelle W5NYV, Paul KB5MU and John KJ6HZ.
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Michelle W5NYV wearing her daughter’s alpha wave ears. The ears move and react to pulses from a sensor clipped to her left ear.
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An unknown couple wearing Vocademy shirts. What a great slogan: Eat, Sleep, Make.
After Field Day and the demonstration at the Discovery Science Center in Santa Ana, CA last month, I decided to add information on my TinyTrak APRS units on this site.

I re-packaged the unit to simplify deployment and to make it more practical for a “grab and go” event. On the left is a two meter (144MHz) hand-held radio, with the battery pack removed, and powered by external 12V via the DC IN jack. The TinyTrak 2 is next to the HT, in a die cast aluminum case (Hammond 1590B). On the bottom of the box is an old Garmin GPS 45XL and a 12V wall-wart type AC power supply. The bottom of the box also stores a magnet mount antenna for radio, an external GPS antenna and a DC power cable. There’s plenty of room for a gel-cell.



Under Construction
After completing the HB RACES KH6WZ APRS Beacon above, I decided to do a similar thing for my old Garmin Street Pilot. In this version, the GPS unit will be mounted on the outside of the cabinet so the map display will be visible. An inexpensive Radio Shack HTX-252 two meter mobile rig (bought new on a close-out sale years ago) is mounted to the top panel. This unit will be capable of high power operation (10 Watts low power, 25 Watts on high power) to get the signals out in fringe areas. Here are some pictures of the unit under construction. The aluminum chassis box is a surplus instrument case. It is nice and rugged, with a handle on the top.
Here you can see the mobile rig at the top left, a row of LEDs to indicate APRS status, the TinyTrak unit and a small perf board with RCA jacks for the GPS signals coming out of the Street Pilot.

Here is a close-up of the TinyTrak PCB and a break-out board for the unit. Switch M1/M2 selects the primary or secondary message programmed in the TinyTrak; switch D1/D2 selects internal display (D1) or the external display (D2). More details on these functions appear below in “One Way to APRS Beaconing.”

Here is a bottom view of the TinyTrak motherboard…. Mounting the TinyTrak this way will help preserve the PCB trace pads and should help simplify access to the wiring when and if it needs repair.

The following information is based on my original article called “Where in the World – A Look at APRS” in the CQ Magazine Beginner’s Corner for November 2003. Click here to see the table of contents of this issue.
I’ve always been fascinated by those “tracker systems” used in the movies and television. You know, like the scene in the movie “Armageddon,” where the ground controllers are watching each member of the “A” and “B” Shuttle teams. Or the “homer” made by “Q” in the James Bond movie “Goldfinger.” I found an expensive and fake homer here, but it is just a fancy sound maker with an LED – take a look at this thing. . .
Today, and in the real world, hams have access to this interesting technology: It’s called the automatic position reporting system (APRS), developed by Bob Bruninga, WB4APR. Basically, it uses latitude and longitude information from the global positioning system (GPS) satellites and transfers the data via packet radio on 2 meters. Mix an APRS station with the Internet, and we have a system in which hams can keep track of moving objects remotely. Interfaced with a suitable weather station, local “micro-weather reports” can be viewed. If you know anyone into APRS, take a look at the N1BQ Web site and plug in their callsign into the search field. You’ll be able to see what he or she has been up to (or at least where they went) lately.
Several members in the local radio amateur civil emergency service (RACES) group made “tracker boxes” and use them for special events, like the Baker-to-Vegas Challenge Cup Relay race. When I saw their APRS systems for the first time, I thought, “Hey, that’s really neat.” Then I went, “Hmmm. What would I do with such a thing?”
Like a lot of hi-tech gadgets, if you think hard enough, you will come up with a lot of reasons to build, buy or otherwise own one. Here are some examples of what you can do with an APRS tracker box:
- When interfaced with a compatible weather station, the APRS beacon can also transmit weather information
- If you are involved with a public service group, you can watch where a person or vehicle is in near real time
- You can re-trace and display your driving, sailing or boating routes via the Internet, and friends and relatives can watch, too
- Put that working but old and un-used 2M HT or mobile radio to good use
Remember that an APRS unit is an Amateur Radio beacon, and must comply with FCC Rules on Beacons, One Way Transmissions, Station Identification and Stations Under Remote Control.
In order to have a moving APRS station, you will need a 2 meter station (rig, antenna, power source), a terminal node controller (TNC) with APRS capability, a computer and a GPS unit. If you are doing packet radio now, or have some packet gear in the closet someplace, you are already more than half way there. By the same token, if you enjoy boating or camping, you may already have a GPS unit.
2013 UPDATE: Many VHF mobile rigs – and some HTs too – come with an APRS capability either built-in or have this feature available as an internal option. This is pretty amazing and shows how fast technology can change.
Here are some notes about what you need to make a simple APRS beacon.
The GPS Receiver and Antenna
The GPS unit does not have to be new – and, in fact, older units might actually be better, since the newer units have gone to the small MCX and other exotic connectors, rather than the easy to use and adapt BNC or SMA connector. I use an old Garmin GPS 45XL and a Street Pilot Color Map, both units have been discontinued many years ago.
Almost any GPS receiver can be used for APRS, but a critical feature the GPS unit must have is a connector port for serial data output in the National Marine Electronics Association (NMEA) format. Just about all “camping” and “marine” GPS units have this data interface.
I suggest looking for the following features, in this order of importance:
1) Ability to access the GPS data output via a serial port. Check to see if the data interface cable is available, or can be easily made or modified. See an interesting alternative source for Garmin-compatible accessory plugs in the Reference section.
2) Ability to use an external antenna. In essence, all GPS units are radio receivers, and, just like your radios, require a good antenna for the best performance.
I have found amplified GPS antennas on eBay and other places for as little as $20. Some GPS modules include a patch type antenna built-in. This may or may not be optimum for use in the field, but today’s GPS units have much more channels than the 10-plus year old units I am using for my system.
3) Ability to apply external 12VDC power. Small penlite cells can get expensive after a while, so the ability to plug into an alternative power source would be good. Be aware that some units need a power source lower than 12V to 15V, and can be damaged if 12V is applied directly to the unit. But do not fret, if your GPS unit needs something other than 12V, you can build or buy a suitable voltage converter to handle this. The simplest way to use external power is to see if the unit has a cigarette lighter accessory or some other external DC cable, and use that. For non-automotive use (like pedestrian mobile), you can remove the cigarette lighter plug and use a gel-cell or other 12V power source.
Garmin seems to be the most popular GPS units for APRS. I think their excellent customer service contributes to this, based on personal experience.
Full-featured GPS units might be a bit extravagant for just APRS applications, so if you are not into flying, backpacking, sailing or other activities requiring navigation, you might want to consider a GPS “module,” rather than a GPS “receiver.” The GPS module is just a “plain data receiver box” with no display, and is intended for use with some other gadget, such as a computer. Because no other “support electronics” is involved, prices for GPS modules are much cheaper than GPS navigation units.
The Interface and the Rest of the Components
An APRS interface is the “brain” that transfers the digital location data from the satellites and instructs the radio transceiver when to transmit and when to receive. More sophisticated units can interpret more GPS information, and transmit more than simple latitude and longitude. For example, on a moving vehicle, the APRS unit can send not only position, but also speed, rate of climb or rate and direction of turn, altitude, a station identifier and an icon.
There are dozens of different symbols used in APRS to indicate what sort of object is being tracked. For example, my friend Peter Barbour, N6RAS, is an avid sailor, and uses a boat icon when he is “beaconing.” Bill Honeyman, KG6CNL, uses a jeep, and Steve Graboff, W6GOS uses a “running man” symbol during the Baker to Vegas race. The eye icon was used during the demonstration at the Discovery Science Center, see the screen capture below.

One Way to APRS Beaconing
There is a simple way to try APRS. The TinyTrak unit, by Byon Garrabrant, N6BG, is a wonderful little circuit that eliminates the packet TNC. If you have a “TT,” all you need is a GPS receiver, a two-meter radio, antennas for the GPS and radio and a power source. The unit is configured via the serial port in your personal computer.
Now in its fourth generation, the TinyTrak units are available in a “fully-assembled” version, complete with a small 2 meter transceiver. The older generation small PC board versions of the TinyTrak are still available.
My units vary somewhat from the “out-of-the-book” instructions. I added an SPDT, center-off toggle switch to make a “test” function: In the test mode, the unit is powered up normally, and the LEDs blink to verify operation. After checking the blinking lights and verifying the two meter rig transmits data, the switch is thrown into the “operate” mode, which simply cuts off the ground connection to the LEDs (making them go off) to conserve battery power.
I recently added another modification: I added another SPDT switch (not center-off) so I can select either the small internal LEDs or the large front panel mounted LEDs when the unit is in operation. This is done to create a “light show” to attract attention during demonstrations.
Remember that the TinyTrak is a simplified beacon device. It will not receive and decode APRS data for display purposes. It is the “data transmitter beacon” or “homer” part of an APRS set up, but they are fun nonetheless.
Once you get your APRS beacon going, I am sure you will want to do more. In the meantime, the simple starter system will enable you to beacon your position while you do your favorite radio-activity, from public service to outdoor events. James Bond’s homer technology is here for hams, and is an exciting and interesting bit of technology we can use just for kicks or for serious public service assistance.
Links to More Information
General APRS info
http://web.usna.navy.mil/~bruninga/aprs.html
http://www.aprs.net
http://www.tapr.org
APRS Symbols
http://www.aprs.net/vm/DOS/SYMBOLS.HTM
See Beacon Locations on the Internet
http://www.wulfden.org/APRSQuery.shtml
TinyTrak “TNC-less” APRS kits
http://www.byonics.com
Carter, Jim WB6HAG, “Build an APRS Encoder Tracker,” QST, February, 2002, page 28
GPS Modules
http://www.makershed.com/default.asp
An Interesting Connector Source for Garmin GPS Units
http://pfranc.com
Baker to Vegas Challenge Cup Relay
http://www.bakervegas.com