Richardson "5" Update

Thanks to members of the excellent Antique Radio Forums and to a Mr Richardson (No relation, I think) I have found out more about the history of this receiver. It turns out that the set had been restored in the past from fairly sad shape after being purchased at an AWA swap meet in New York.

Underneath the top desk of the radio is the text "Oct.17.1996 Billy Richardson" which confirmed that the radio had originally passed though his hands while being brought back to life.

However I'll let Mr Billy Richardson tell the story in his own words:

I'm guilty of owning the Richardson "5", guys. It was in poor condition when I bought it in an AWA swap meet in New York way back there years ago. I restored it to the best of my ability to its original condition a few years later. It was not a restoration that had anything special going for it, so it was never shown in any of the contests around the country. It was working OK when I finished it, but I can understand why it doesn't work now.

To the best of my recollection, Richardson radios were first advertised as a superheterodyne kit. Their main feature was "self evident wiring", or something like that. Naturally. they didn't get away with selling a superheterodyne kit and the next and only ad I saw after that was a small one for the Richardson "5". It used the same type of wiring.

Here again I speak from a poor memory, but the wiring for this set is one long piece of rubber coated flexible wire. Along its entire length it has lugs that simply pierce the rubber cover to make an electrical contact. Not a good thing, because only one or two strands of wire may be making contact and a wee bit of oxidation is all it would take to break the connection. This was the case with the original wire, which was also hard and brittle. I replaced it with NOS flexible wire that looked exactly the same. The finished job is an ugly sight, just like the original. All the lugs are spaced an equal distant along the wire, regardless of how far it has to go to the next connection and most of the wire is too long for those connections. In other words, it's a jumbled up mess of wire and not something to be proud of.

I recognized the photo of this set immediately as being mine because of the label under the lid. There was enough of the original left to make a good copy and I thought the reproduction turned out real well.

Billy Richardson

Alan Douglas of the Antique Radio Forums found a clipping from Radio Retailer & Jobber Oct.1925 which told of Mr Richardson's exit from the Richardson Radio Corporation. Given the very short period where any advertisements were made it seems like this corporation didn't last very long at all, perhaps only a year or two at most. In the Radio News of 1925 the January issue has quite a large advertisement while the December issue has only the smallest note possible ... perhaps a sign that things were not going particularly well.

The only additional information I could find regarding either the Richardson Radio Corporation or Mr Richardson himself come from the clipping of the Princeton Alumni Weekly, August 1936.

Unfortunately it concerns what must have been his early death and does not specify the cause which would have been appropriate at the time.

DAVID WELLES RICHARDSON '22
The Class records with deep sorrow the death of our classmate, David W. Richardson, who died at his home in Mt. Kisko on July 16.
Dave spent the first two years out of college in the radio business. He helped organize WOR and was the president of the Richardson Radio, Inc.
He then entered the employ of Joseph P. Day and for five years was head of the private sales department. About a year ago he entered the brokerage business with Harris, Upham & Co. and on July 1 entered the employ of Eastman, Dillon & Co.
Dave was married in 1932 and has a son, David Welles Richardson, Jr. To his widow, his son, and his father we extend our deepest sympathy with the assurance that we will not soon forget him.
    For the Class of 1922
    William E. Stevenson, President
    G. M. L. LaBranche
    Hunt T. Dickinson
    Robert Buechner, Secretary. 

The unfortunate & epic saga of the perfect military radio

The long awaited but ultimately unwanted GMR radio

As my day job starts to include more long term projects & project management I was particularly intrigued by an article in arstechnica.com. The article is, "How to blow $6 billion on a tech project", although the title may be more inflammatory than technically accurate.

The article covers the 15 year development of an advanced & unified military radio communications system that suffered from multiple issues including scope-creep & a rapidly changing underlying technology.

If you are involved with a group that is working to develop a product or service you'll really get something from this article. If you interested in radio systems, military or otherwise, you'll find this interesting as well.

Its hard to image the frustration people suffer when contributing to a project that is mismanaged unless you have been there yourself. I hate to think of the wasted effort that resulted when people found out How to blow $6 billion on a tech project

The further adventures of the Heathkit AT-1

Work has been conspiring to eliminate my spare time but I was able to spend a few hours over the Easter holiday to clean up the shack and make space to put the Heathkit AT-1 on the desk again. I have been able to spend a little time going over parts that need to be replaced and making a list.

The Heathkit AT-1 chassis with case and VFO-1 behind.

There doesn't seem to be any show stoppers although the wafer of the meter switch has broken in two and will need to be repaired. If I'm not able to repair it then thankfully it is fairly simple and replacement rotary switch can be substituted.

This isn't going to be a museum quality restoration but the changes that were made to this transmitter in the past were sensible and if left in place are representative of period modifications. The original meter for example was not the highest quality and a Western or Simpson replacement would be an improvement. The original slide switches have been replaced with period snap-toggle switches which are also an improvement over the original.

The Heathkit VFO-1 however has been modified for grid-block keying which is a significant departure from the original and I plan to revert it back to cathode keying. Although a technical improvement it is not in keeping with the original design and needs to be undone. Everyone will have their own opinion but I think if I wanted modern circuits I'd get a more modern rig, so the VFO-1 will be returned to stock.

Hopefully I can carve out a bit of time here and there to work on this and slowly return it to working condition.

DIY Magnetic Loop Antenna - Part 3

Well, I finally have had time to sit down and put together part three of the DIY Magnetic Loop Antenna, sorry it has taken so long!

This post will cover building and coupling the loop to your transceiver. After reading through posts one and two you should have a good idea of the parts you'll use and the physical dimensions of the main loop.

DIY Magnetic Loop Antenna - Part 1
DIY Magnetic Loop Antenna - Part 2

Most magnetic loops have the capacitor at the top of the main loop and the gamma match or matching loop at the bottom, this arrangement avoids running the feed-line through the center of the antenna.

You can assemble the main loop from continuous copper tube or from eight straight sections and 45 degree joiners. Make sure you have a blow torch or propane torch to solder the joints as you'll need more heat than a soldering iron can supply. Whichever way you decide to build the main loop make sure that all joints are soldered or clamped as securely as possible, you want the lowest resistance possible to avoid your output power turning into heat. Other materials can be used for the main loop such as aluminium or low loss coax but copper pipe is easy to work, has low resistivity and available from just about every hardware store.

To construct the frame of the antenna you can use PVC pipe. It is a cheap and relatively sturdy building material and is available in a range of thicknesses, just about any hardware store will stock a wide selection of fittings. It insulates well and can be glued once you are sure your project is in its final form.

Once the main loop is constructed you'll need to connect your capacitor to the two ends of the pipe at the top of the loop. Depending on the capacitor you may want to solder tags to the ends of the loop so they will be easier to attach. Copper pipe is a great conductor of heat and takes a lot to heat up and solder while it is not advisable to apply the same amount of heat to your capacitor.
It is also a good idea to attach the capacitor to a solid support so that the connections are not under strain.
The main loop and the capacitor forms the resonant circuit of the magnetic loop antenna.


To couple the main loop to your transceiver and match the expected 50 Ohms impedance you can use one of two methods. Probably the easiest is to use is a loop of insulated wire 1/5 the circumference of the main loop. The smaller loop is placed at the bottom of the main loop and can be shifted around to provide the best match. If you have an antenna analyzer you'll be able to set it to the desired frequency, tune the variable capacitor for resonance and then move the small matching loop around till you have achieved close to 1:1 SWR. If you don't have an antenna analyzer you can tune the capacitor for the greatest received noise and then on low power tweak the capacitor and move the coupling loop around for best SWR. Do NOT touch the loop while it is transmitting, use a wood or plastic rod to make adjustments as there are high voltages and intense RF fields near the loop.
An alternative to the coupling loop is the gamma match. The shield of the coax feed cable is connected to the base of the main loop while the inner conductor is connected to a point approximately 1/5 of the circumference around the loop. Its a good idea to use stiff wire (large gauge) for the gamma match as it can be critical of the position and orientation and once you have it in the right position you won't want to move it again.

It would be preferable to have the ability to remotely tune the loop. A motor with a reduction gear could be used to move the variable capacitor but because the point of resonance is very narrow there should be a way of slowing the motor down. A simple control circuit using variable pulse width modulation could be used to slow the motor down while still retaining enough torque to move the capacitor. Whatever method is used to move the capacitor it should be well insulated from the other components of the antenna. Several thousand volts are generated on the MLA and care should be taken to ensure they don't find their way onto control leads and back into the shack. Control leads should also be wrapped around toriod inductors as they leave the near field of the antenna to reduce the possibility of RF travelling along them.

With a SWR bridge and microcontroller you could build a fully automatic tuner that swept through the range of the tuning capacitor when the SWR rose above a defined limit indicating that the transmit frequency had changed.

With a little creativity and knowledge you could have an impressive MLA the equal of multi-thousand dollar military style units.

Hopefully this has given you some ideas for constructing your own loop antenna. Regardless of if you go top-of-the-line and buy a vacuum variable or build for economy and QRP you'll have a compact, useful and unique antenna.

Now I understand - Phase Locked Loops

Every now and then I come across great books or videos that explain a concept in such a way that it becomes immediately obvious what is going on. I'm a great believer in learning by demonstration or even better, learning by doing.
I came across another explanatory video recently that I thought was too good to keep to myself. It covers a topic that was a complete mystery to me: Phase Locked Loops. We utilize them in almost every modern transmitter and receiver yet most people I have talked to view them as a black box that, fortunately, does its job well and usually without interruption.
The video below does a good job on opening the black box and showing just what makes phase locked loops ... well, lock.

The Power of Making

A brilliant video detailing the power of making through a triptych of views into the workshops of makers.

A three screen film installation for the Power Of Making exhibition. A collaboration between the V&A and the Crafts Council, this exhibition presents 100 crafted objects in a cabinet of curiosities that explores traditional and time-honoured ways of making, as well as innovations taking place around the world.

Visit the Victoria and Albert Museum at http://www.vam.ac.uk/

Radio Kits that Teach

There continue to be great kits produced that aid in learning the fundamentals of radio theory and construction. Two that I really admire are the Elenco radio trainer kits, available in both AM/FM and AM only versions. They do require some soldering so, if you haven't soldered before, I would recommend a soldering starter kit like the AmeriKit Learn to Solder Kit or similar. The AmeriKit costs around $15 and includes a basic soldering iron.
Possibly the best part of the radio kits are the detailed instruction manuals that step through the theory behind each section as it is constructed. This is more than just a assemble and go kit, the aim is to come away with an understanding of how radio signals are turned into intelligible audio.
Both Elenco kits are available from a variety of retailers, you can source your own or I will include links to Amazon if you prefer.

Elenco AM / FM Radio Kit - $30
Elenco AM Radio Kit - $18

Although this probably sounds like an advertisement for the Elenco kits I'm not affiliated with Elenco, I just happen to like their kits and educational gear.

Incredible materials : Ultra dense plastic - Malleable at just 150F

Ham radio folk have been home brewing, inventing and crafting before most Makers were a gleam in their parents eye but that doesn't mean we can't learn from those industrious Maker guys. One area that is receiving more and more attention has been new and innovative construction materials.
Most of us are familiar with the concept of cutting a plastic chopping block up to make insulators but what would you do if you needed to create a molded part or something more complex? Injection molding is expensive for one off parts and anything more complex than drilling a hole also requires a substantial investment in machinery.

A new material that goes by several names (Shapelock, InstaMorph) is malleable at just 150 degrees Fahrenheit (66 degrees centigrade) and cools to an ultra-dense plastic similar to nylon.
It can be molded with your hands when heated and machined with low speed tools when cool.  I couldn't find specific details but I imagine it has similar dialectic properties to nylon which would make it suitable for a wide range of radio and electronic applications. Perhaps you'll be the first to add this material to your arsenal of home brewing tools?

Check out the demo below which shows how easy this material is to mold using simple tools or just your hands. You can get Polycaprolactone under several different brand names such as Friendly Plastic, InstaMorph or Shapelock from a number of different suppliers or search for it on Amazon.

Twittering Morse Key - Tworsekey

I'm certainly not the first to theorize that if there is a greater than zero probability of something happening then you'll find it happening on the Internet. So it was when I stumbled across this home brew creation of Martin Kaltenbrunner. Martin has created a Morse code key that decodes whatever you hammer out and sends it to a Twitter account, thus neatly bridging more than 160 years of history while ranking fairly high on the, "But why?" scale. I have no idea why Martin created the Tworsekey but you have to admit that it looks great and I wouldn't mind having one siting on my desk.

Hellschreiber and microprocessors - Bridging more than 80 years

ZL1HIT (Bryan Rentoul) has bridged a gap of more than 80 years by combining the text transmission system developed by Rudolf Hell in the late 1920's with current microprocessor technology.

A sample of received Hellschreiber test from Bryan's beacon

Hellschreiber sends a line of text as a series of vertical columns. Each column is broken down vertically into a series of pixels, normally using a 7 by 7 pixel grid to represent characters. The data for a line is then sent as a series of on-off signals to the receiver, using a variety of formats depending on the medium, but normally at a rate of 112.5 baud.

This process was historically accomplished with mechanical equipment but there are very few examples of this equipment still in operation and it is now sent and received by computer. Hellschreiber is very tolerant of noise and interference and requires only simple transmitters and receivers to work effectively.

German Hellschreiber unit in operation

With a microprocessor generating the digital on-off signals a simple crystal oscillator transmitter can be used to form a beacon station, one that transmits a call sign and perhaps some other information over and over. Changing the transmitted message is as simple as reprogramming the microprocessor or having it respond to a connected input, for Eg. A thermometer, light sensor, switch, etc.

Receiving the signal and decoding requires a radio receiver capable of CW reception and a computer running any of several free software packages like FLdigi or Digital Master 780.

The ZL1HIT beacon using a PIC microprocessor and a simple crystal oscillator transmitter.

For more information and the PIC microprocessor source code please visit the web page of Bryan Rentoul here : ZL1HIT Hellschreiber / PIC Beacon

Homebrew Hero - Homemade NBTV video recording system in 1974

What do you do in 1974 if you are 20 years old and want to send video to other Amateur Radio operators?

An off-the-shelf home-video camera was the equivalent of $8000 USD (if you could find one) and the circuitry required to transform the high bandwidth signal into one that could be transmitted on AM would have been prohibitively complex.

Believe it or not the only solution was to build your own narrow band video camera! These creations followed on from narrow band television work done in the 1930's and took advantage of advances in materials and solid state technology.

The camera used by VK3AML (Chris Long) in the video below was a Flying Spot Scanner camera which required a completely darkened room and used a spot of light that scanned the scene. The reflected light was picked up by a photomultiplier tube and recorded as a frequency modulated audio tone on tape or broadcast via radio.

We're fortunate to have some of the original video preserved from 1974 since the audio and video signals had been recorded onto open-reel tape.

The 30 line television system developed by John Logie Baird in the 1930s allowed home experimenters to build their own equipment, a practice which still exists today through the Narrow-bandwidth Television Association. Relatively few narrow-band TV signals are transmitted nowadays so most amateur radio operators are unaware of this special interest group.

The video below shows some of the actives and projects that members of the Narrow Band Television Association have been involved in and gives some historical background on this interesting field.

Chas (WA1JFD) from the Antique Radio forums mentions that at approximately the same time other amateur radio operators such as Donald Mara (WA1PLT) were experimenting with Slow Scan Television (SSTV). SSTV sent higher resolution pictures at a slower frame rate, typically taking 8 seconds to send a complete image. Below is a picture of some of the first commercial SSTV equipment that was made available to US hams.

Robot 70 (monitor) & 80 (camera) SSTV system introduced in 1970

I wasn't able to find exact prices for SSTV equipment like the ROBOT 70 & 80 but period articles seem to indicate you wouldn't get much change from $1000 in 1970 for a complete SSTV station. This is equal to around $5000 USD today.

An oscilloscope clock - Recycling vintage equipment without destroying it.

As a fan of vintage electronics, and vintage technology in general,  I love to see things being re-used rather than being dumped in the trash. This has the very desirable effect of preventing sometimes toxic chemicals from being released into the environment and reduces the demand for new parts that can also involve toxic chemicals during their manufacture.

The only downside to this recycling is that frequently the original function of the equipment is lost so I was pleased to see this creation from Bob Alexander. He has combined one of the oldest types of test equipment with some of the newest microprocessor based devices to bring us a Oscilloscope Clock that still functions as an oscillloscope!

Heathkit oscilloscope with AVR Oscilloscope Clock module

Bob ran into some problems while installing the AVR Oscilloscope Clock Module but was able to invert the horizontal output from the clock module before feeding it into the scope. To read about his build in detail have a look at : An Oscilloscope From the Trash

A small modification to the rear panel to allow setting the clock and switching between clock and scope.

Check the video below for a demonstration of the Sparkfun AVR Oscilloscope Clock Module in action on a significantly newer oscilloscope.

Mapping your ADIF logfile to Google Maps

I had tried Google-mapping a while back with limited success, manually kludging together several utilities until I got a Google map of my contacts. This new utility from K2DSL makes the operation VERY easy.

Just select your adif log file (You can download yours from Logbook of the World or export one from your logging software) and click Upload and Map. You may want to enter your home grid square if you have issues with the contact origin or the map looks strange as I did.

Select your adif file, set your home gridsquare and map it!

The output will be familiar to anyone who has used Google maps but with the additional option of being able to download a kml file to use in Google earth!

France, on a magloop, in the garage.

With Google earth it becomes obvious very quickly which way your antenna favors and where you are reaching. Clicking on a contact opens up the time, band and mode information if it was recorded in your adif log, very smart.

East coast - yes, West coast - not so much.

A very useful piece of work from K2DSL, available at his website http://www.levinecentral.com/ham/

Amateur radio event helps youths connect to others around the world

An important part of Ham Radio is public service and while not every ham has the time or ability to contribute, those that do are able to connect to communities in a very meaningful way.
Ham Radio can provide a communications service that is very different to the corporate product of AT&T or Comcast. Ham Radio is an essentially a grassroots organisation drawn from the community itself.

A recent article in the Daytona Beach News-Journal highlighted some of the activities during Amateur Radio Kids Day ...
Mark Estes, Correspondent for the Daytona Beach News-Journal

PALM COAST -- Herschel King Sr. Park was abuzz with activity as members of the Flagler Amateur Radio Emergency Service Organization and Flagler Palm Coast Amateur Radio Club joined in Sunday for the American Radio Relay League's national Children's Day event.

Before the event officially began, there was plenty to do as members of both clubs readied a number of radio set-ups. With the help of members of Palm Coast Boy Scout Troop 402 various antennas were deployed in the trees in preparation for a day of contacting amateur radio enthusiasts around the continent.

The dozen Boy Scouts, along with parents and Scout leaders, bicycled 10 miles to the site as one of the requirements for their cycling merit badge. Eight of the Scouts are working toward their radio merit badges and for some, this outing would complete the requirements for the badge.

During the day, other families visited to learn about amateur radio and this was good news for Bill Schwartz, Flagler County emergency coordinator for ARES.

"We're introducing amateur radio to youth," Schwartz said. "For the Scouts, they're going to try to get some requirements for their merit badges. For us, it's practice so if there were a disaster we could set up an HF station anywhere."

The order of the day was to have the licensed adults make the initial contacts and then hand the mic over to their charge for a conversation.

"We expect to be able to get the United States, Canada and South America," Schwartz said. "The kids have to spend 10 minutes on the air for the merit badge. So far it has been all theoretical for them. There are certain places where we're going to try to get in touch with other kids."

Any contact and conversation was good. If the prospect of talking on the radio to strangers, mostly adults, was a bit daunting, Jake Dobson, 11, never let on. Despite a bit of local interference, Jake confidently held the mic and made the appropriate acknowledgments while learning a bit of conversational radio shorthand from John Woika. He made his required contacts in good order.

"It was interesting and fun," Jake said.

The day started a little rougher for Coby Queen, 12, as an equipment malfunction resulted in a fall and a scraped arm during the 10-mile bike ride. Things started slow for him on the radio as well. The first contact his adult partner, Norm Riquier, found was in an extended conversation; the next faded before he could talk to them. Getting a good signal was elusive, but eventually Coby contacted New Mexico and then, Guatemala.

Michael Levin, 13, and Ian Medley, 16, got a bit of a treat when they did their radio work in Mike Lee's communications van. Chief innovation officer at Palm Coast Data, Lee designed and equipped it as a proof-of-concept van seemingly capable of very type of communications except smoke signals. Lee and assistant emergency coordinator Eddie Cail served as adult partners for Levin and Medley.

The older hams would certainly like to see some of the participants take up amateur radio as a hobby.

"We have a 119 merit badges in the program and the boys usually go into some profession or pick up some hobby out of these during their lifetimes," Scoutmaster Tony Conti said.

This is the first time the Flagler clubs have participated in the national Children's Day event, but they expect to be doing so again in the future.

"We're hoping to do more of these throughout the year, keeping the kids active and give them something to do," Cail said. "The bands are really hot right now for a lot of radio stuff so we're hoping to make some good contacts and let them see what it's like to get on the air."

More information on ARRL Kid's Day is located here : Kids Day 2012: Sunday, January 8 & Saturday, June 16

Deathrays and the garage home-brewer

In days past home-brewers would often be at the forefront of new and developing technologies. Apple Computer got their start in a suburban garage, Marie Curie refined radium in little more than a garden shed and the founders of Hewlett Packard worked out of a home garage in Palo Alto.

Unfortunately we moved away from encouraging kids to "tinker" in the garage and instead we've supplied ready made entertainment in the way of game consoles, demographically targeted TV and an endless series of extra-curricula activities ... all ultimately aimed at preventing boredom and keeping kids busy.

To see some impressive tinkering, take a look at this great build from Teravolt.org. Its certainly something that could be dangerous if used incorrectly but the assumption that something is unsafe unless proved otherwise and the knowledge to know the difference is sometimes better that relying on a commercial manufacturer's assurance that everything is ok ... because sometimes it isn't.

X-Ray Machine from Teravolt.org

I don't think well raised kids will take to the streets in rampaging mobs if they are allowed to become 'bored' and I think there is the possibility that through their inventiveness they will discover and create things we haven't even imagined. Given the tools, basic education & a measure of respect we could see more garage pioneers in the coming years. While I understand the value of robot kits and 'following directions' I am more enthusiastic about the Maker movement and the great selection of micro-controllers and electronic building blocks they have created.

Looking through a hard-drive using the Teravolt.org X-Ray source

New video from ARRL : The DIY Magic of Amateur Radio

From the ARRL:
ARRL's new video, "The DIY Magic of Amateur Radio," is an 8-minute video that follows some of the innovative, imaginative and fun ways "hams" use radio technology in new and creative ways. The presentation is directed toward the DIY (do it yourself) movement, which is inspiring a new generation of creators, hackers and innovators. The message should be helpful for existing members to shape the ways they understand and talk about ham radio.

From Christmas tree lights to slippers, how tree lights are recycled

Most of us have seen glass and plastic being recycled however recycling of consumer goods made with multiple materials can be much more challenging. In the past Christmas tree lights have been burnt to obtain the copper but this releases a slew of toxic chemicals into the air from the burning plastic. A better solution has been found by a Chinese recycling company that specializes in recycling all the material from light strings once they have served out their time on trees, roofs and gardens.

Coil Winding using the Gingery Coil Winder

Anyone who has seen the video below from KC9KEP will probably be wondering where he got the coil winder used to make those high Q coils with universal windings.

The design itself is based on the Morris Register Company (MoReCo) Coilmaster and modified for home brewing by Dave Gingery. His excellent book is available from lindsaybks.com and provides plans that use parts and tools commonly available in the home workshop.

Gingery coil winder by KC9KEP

Another resource for coil winders is a page from K5BCQ that shows the original Coilmaster, a different home brew plan and a large volume of useful information.
A vintage text is also available which covers inductor (coil) design in significant detail and should be downloaded by anyone who REALLY wants to know what they are doing. It is available here.

Preserving the past - Australian built broadcast transmitters

Arguably some of the best looking radio equipment was produced in the 50's and 60's when art-deco motifs, streamlining and other elements of design made their way onto consumer and even industrial electronics.
Unlike modern times, when cost is the only consideration, designers and engineers took the time to ensure that their creations looked good as well as being functional and long lasting. It was worth taking time over the placement of meters, switches & panels, even if it did mean that the final product cost a few dollars more to manufacture.
Amalgamated Wireless (Australasia) or AWA produced an extensive range of home and commercial equipment in the 60s and many vintage radio collectors have examples of AWA radio receivers in their collections. The larger equipment like broadcast transmitters takes an extra special effort to preserve as their large size, demanding power requirements and the specialized knowledge required to maintain them presents a barrier for all but the most dedicated enthusiasts.
We are fortunate then that Don Bainbridge has taken up the challenge and preserved a remarkable collection of Australian built broadcasting equipment and maintains much of this equipment in operational order. The YouTube video below and his website linked here offer a rare glimpse into the world of vintage high powered broadcast equipment before plastic took over and economical design stripped away the chrome and pinstripes.

Better than X-Ray glasses

While not as simple as putting on a set of EM vision goggles this is still opens the window into visualizing radio waves and allows us to see what we previously had to imagine.

Greg Charvat N8ZRY just published this video showing off a very cool experiment with the low-cost coffee can radar system he and co-workers developed, in the fall of 2010, for MIT’s open courseware initiative.

In the video, Greg describes and demonstrates a simple circuit that causes a red/green LED on the receiving antenna to glow one color when the amplitude of the received wave is positive, and another when it is negative. Moving the LED back and forth in front of the transmitter, while taking a long-exposure photograph, gives a visual map of the wavefront in space.