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

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.

Now I understand - Standing Wave Ratio (SWR)

There are great books out there that explain radio principals in a plain and straightforward manner. Many are vintage military manuals whose primary aim was to give a functional understanding of the theory involved without getting caught up in the interesting but ultimately unnecessary details.

Modern material on the other hand can sometimes miss the mark of providing a functional understanding in favor of trying to completely address the high level theory and leaving practical matters to be addressed later ... or perhaps never.

The AT&T training video certainly hits the mark when it comes to explaining and showing the properties of radio waves. It shows how they are affected by termination and changes in impedance, what resonance looks like, how terminated and non-terminated lines reflect waves and much more.

Material like this is well worth the time of anyone who has an interest in radio or electronics.

More video are available from the AT&T archives here : http://techchannel.att.com/showpage.cfm?ATT-Archives

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.

Pop's Shed and the Kingsley Radio AR7

After my grandfather passed away I spent a lot of time recalling the good times I had spent scrounging around his CB shack and hanging out with Pop "down the shed". If you've spent time around old motorbikes, retired lawn mower engines, vacuum tube electronics and inches of dust you know what the shed smelt like and probably have a pretty good idea what it looked like as well.  I used to be able to send Mum into fits by embedding a combination of oil, grease, dust and grinding compound into the knees and sleeves of my good clothes after spending the day "over south" (South Geelong)

Even now I can still walk into any old auto mechanics and the smell brings back dozens of memories as clear as day ... but one memory in particular had been bugging me for a while now. On several occasions I had used a magnificent rack mounted shortwave receiver that had been hooked to a long-wire antenna between the shed and the house. It had several plug in coils housed in bright metal boxes, one for each band as well as a unique tuning dial that had windows around the circumference with numbers that updated as the dial was turned.

National HRO right? ... Nope, its an Australian clone!

For the longest time I was thinking what you are probably thinking now, I had been using a National HRO receiver right? Well, you'd be wrong ... just as I had been for years! When I eventually asked my uncle about the receiver (I waited a long time as I feared it had been thrown out & honestly didn't want to know if it had) he said, "The AR7?" ... "Yes, its here in the garage covered in dust". He went on to say that I could have the receiver if I could figure out some way to ship it ... not a slight problem given the receiver, power supply and speaker are over 120 lbs!

Knowing now that I had been using a completely different receiver I set to work and found out what I could about this National HRO clone ...

From : http://www.vk2bv.org/

The AR7 was produced during WW2 by Kingsley Radio of Melbourne for the R.A.A.F. These receivers were used in ground stations for long range communication over fixed circuits as well as for receiving signals from aircraft.

The AR7 was based largely on the National (USA) HRO model, a fact that did not go unnoticed by National. This was the subject of litigation during the war years. Over 3000 of these receivers were produced and for their time, produced excellent performance.

These sets were very popular with radio amateurs after the war and unfortunately subject to many modifications. The Wireless Institute of Australia station, VK2WI at Dural New South Wales was equipped with modifed AR7's for many years. I seem to remember that very local operators could block the receivers completely, resulting in hurried phone calls!

An unmodified AR7 is a rare beast. The Department of Civil Aviation used these sets for many years in a highly modified form, requiring a new front panel. Refinements included squelch and crystal locked coil boxes.

From : http://www.shlrc.mq.edu.au/~robinson/museum/AR7/

The AR7 is a communications receiver covering LF and HF bands. It was made in Australia during 1940 and bears an extremely close resemblance to the National HRO receiver. The receiver has a tuning range from 138 kcs to 25 mcs, with a gap of 45 kcs either side of the 455 kcs IF amplifier. The internal design is a single conversion superheterodyne receiver with 2 RF stages, 2 IF stages, a BFO and an "S" meter amplifier. The sensitivity is quoted as 1 microvolt. The front panel is stainless steel and  it is a very distinctive looking receiver.

It is a good performer, sensitive, has a nice feel, is easy to tune, but hard to find the correct frequency, by reading the frequency from the dial number and coil box graph. It really needs a crystal calibrator.  I use it for the weekly W.I.A. (Wireless Institute of Australia) broadcast, so it gets turned on once a week, and is so stable, than I don't have to retune. It is very clear for AM but a bit fiddly for SSB.

The controls are: RF gain, BFO note, AVC/BFO switch, Adjust "S" meter, Tone, Tuning, Noise limiter, Selectivity, Crystal IN/OUT switch, Crystal Phasing, Audio gain. The Audio gain control has an OFF position which removes the HT so that the coil boxes can be changed.

It has two 6U7G RF stages, a 6K8G mixer, two 6U7G  IF stages at 455 kcs,  a 6G8G detector/AVC/audio preamplifier, and a 6V6G audio output amplifier. It has a 6C8G twin triode as a BFO and "S" meter amplifier. It also has a crystal filter. The IF alignment should be done very carefully, as any misalignment will reduce the effectiveness of the filter. It is best done with a sweep generator. The 6 volt valve heaters are connected in series, for 12 volt operation.

The external power supply and speaker, are usually mounted in a short 19" rack, the AR7 at the bottom, the speaker in the middle, and the power supply at the top. The complete unit weighs about 118 pounds. The power supply was switchable between 12v and 240v.

The receiver was used as a ground monitoring receiver for aircraft. It was extremely stable. The model shown has an R.A.A.F. nameplate, and serial number 1786. The manual I have is a D.C.A. (Department of Civil Aviation) version and is a 1947 issue.

It has 5 plug in coil boxes. The coil boxes are: band A 140-405 kcs, band B 490-1430 kcs, band C 1.420-4.3 mcs, band D 4.25-12.5 mcs, band E 12.5-25 mcs. The Army version had an extra coil box covering 50-150 kcs. The large dial is a 20:1 reduction drive and has graduations from 0 to 500. It acts like a flywheel when tuning across the band, and has an effective scale length of 12 feet. The dial shaft goes into a right angle reduction gearbox and has 2 output shafts that drive 2 dual gang capacitors. The graph on the front of each coil box is used to covert the dial reading to frequency.

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.

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/

PACO C-25 Capacitor Tester

I recently attended the Houston Vintage Radio Association post holiday dinner and participated in the auction held after the meal. It was a great evening and if you have any interest in vintage radio I would suggest getting in touch with the HVRA and becoming a member.
Among other things I walked away with at the end of the evening was a PACO Model C-25 capacitor tester.

The PACO C-25 differs from my Healthkit IT-22b in that it tests both regular and electrolytic capacitors as well as using a 40Mc oscillator to enable a rough measure of capacitance using a bridge circuit.
Most of the time, with vintage vacuum tube equipment, capacitor values need only be "in the ballpark" to function perfectly so a high degree of accuracy is not required. For more accuracy I have a Heathkit impedance/capacitance bridge if required.
I have my doubts how accurate the tester would be when measuring capacitance "in circuit" but otherwise it looks to be a very useful bit of kit!
The users manual should be available here and the circuit diagram is shown below.

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.

A gentlemen hacker, circa 1903

From New Scientist:

A century ago, one of the world’s first hackers used Morse code insults to disrupt a public demo of Marconi's wireless telegraph

LATE one June afternoon in 1903 a hush fell across an expectant audience in the Royal Institution's celebrated lecture theatre in London. Before the crowd, the physicist John Ambrose Fleming was adjusting arcane apparatus as he prepared to demonstrate an emerging technological wonder: a long-range wireless communication system developed by his boss, the Italian radio pioneer Guglielmo Marconi. The aim was to showcase publicly for the first time that Morse code messages could be sent wirelessly over long distances. Around 300 miles away, Marconi was preparing to send a signal to London from a clifftop station in Poldhu, Cornwall, UK.

Yet before the demonstration could begin, the apparatus in the lecture theatre began to tap out a message. At first, it spelled out just one word repeated over and over. Then it changed into a facetious poem accusing Marconi of "diddling the public". Their demonstration had been hacked - and this was more than 100 years before the mischief playing out on the internet today. Who was the Royal Institution hacker? How did the cheeky messages get there? And why?

It had all started in 1887 when Heinrich Hertz proved the existence of the electromagnetic waves predicted by James Clerk Maxwell in 1865. Discharging a capacitor into two separated electrodes, Hertz ionised the air in the gap between them, creating a spark. Miraculously, another spark zipped between two electrodes a few metres away: an electromagnetic wave from the first spark had induced a current between the second electrode pair. It meant long and short bursts of energy - "Hertzian waves" - could be broadcast to represent the dots and dashes of Morse code. Wireless telegraphy was born, and Marconi and his company were at the vanguard. Marconi claimed that his wireless messages could be sent privately over great distances. "I can tune my instruments so that no other instrument that is not similarly tuned can tap my messages," Marconi boasted to London's St James Gazette in February 1903.

That things would not go smoothly for Marconi and Fleming at the Royal Institution that day in June was soon apparent. Minutes before Fleming was due to receive Marconi's Morse messages from Cornwall, the hush was broken by a rhythmic ticking noise sputtering from the theatre's brass projection lantern, used to display the lecturer's slides. To the untrained ear, it sounded like a projector on the blink. But Arthur Blok, Fleming's assistant, quickly recognised the tippity-tap of a human hand keying a message in Morse. Someone, Blok reasoned, was beaming powerful wireless pulses into the theatre and they were strong enough to interfere with the projector's electric arc discharge lamp.

Mentally decoding the missive, Blok realised it was spelling one facetious word, over and over: "Rats". A glance at the output of the nearby Morse printer confirmed this. The incoming Morse then got more personal, mocking Marconi: "There was a young fellow of Italy, who diddled the public quite prettily," it trilled. Further rude epithets - apposite lines from Shakespeare - followed.

The stream of invective ceased moments before Marconi's signals from Poldhu arrived. The demo continued, but the damage was done: if somebody could intrude on the wireless frequency in such a way, it was clearly nowhere near as secure as Marconi claimed. And it was likely that they could eavesdrop on supposedly private messages too.

Marconi would have been peeved, to say the least, but he did not respond directly to the insults in public. He had no truck with sceptics and naysayers: "I will not demonstrate to any man who throws doubt upon the system," he said at the time. Fleming, however, fired off a fuming letter to The Times of London. He dubbed the hack "scientific hooliganism", and "an outrage against the traditions of the Royal Institution". He asked the newspaper's readers to help him find the culprit.

He didn't have to wait long. Four days later a gleeful letter confessing to the hack was printed by The Times. The writer justified his actions on the grounds of the security holes it revealed for the public good. Its author was Nevil Maskelyne, a mustachioed 39-year-old British music hall magician. Maskelyne came from an inventive family - his father came up with the coin-activated "spend-a-penny" locks in pay toilets. Maskelyne, however, was more interested in wireless technology, so taught himself the principles. He would use Morse code in "mind-reading" magic tricks to secretly communicate with a stooge. He worked out how to use a spark-gap transmitter to remotely ignite gunpowder. And in 1900, Maskelyne sent wireless messages between a ground station and a balloon 10 miles away. But, as author Sungook Hong relates in the bookWireless, his ambitions were frustrated by Marconi's broad patents, leaving him embittered towards the Italian. Maskelyne would soon find a way to vent his spleen.

Nevil Maskelyne

One of the big losers from Marconi's technology looked likely to be the wired telegraphy industry. Telegraphy companies owned expensive land and sea cable networks, and operated flotillas of ships with expert crews to lay and service their submarine cables. Marconi presented a wireless threat to their wired hegemony, and they were in no mood to roll over.

The Eastern Telegraph Company ran the communications hub of the British Empire from the seaside hamlet of Porthcurno, west Cornwall, where its submarine cables led to Indonesia, India, Africa, South America and Australia. Following Marconi's feat of transatlantic wireless messaging on 12 December 1901, ETC hired Maskelyne to undertake extended spying operations.

Maskelyne built a 50-metre radio mast (the remnants of which still exist) on the cliffs west of Porthcurno to see if he could eavesdrop on messages the Marconi Company was beaming to vessels as part of its highly successful ship-to-shore messaging business. Writing in the journal The Electrician on 7 November 1902, Maskelyne gleefully revealed the lack of security. "I received Marconi messages with a 25-foot collecting circuit [aerial] raised on a scaffold pole. When eventually the mast was erected the problem was not interception but how to deal with the enormous excess of energy."

It wasn't supposed to be this easy. Marconi had patented a technology for tuning a wireless transmitter to broadcast on a precise wavelength. This tuning, Marconi claimed, meant confidential channels could be set up. Anyone who tunes in to a radio station will know that's not true, but it wasn't nearly so obvious back then. Maskelyne showed that by using an untuned broadband receiver he could listen in.

Having established interception was possible, Maskelyne wanted to draw more attention to the technology's flaws, as well as showing interference could happen. So he staged his Royal Institution hack by setting up a simple transmitter and Morse key at his father's nearby West End music hall.

The facetious messages he sent could easily have been jumbled with those Marconi himself sent from Cornwall, ruining both had they arrived simultaneously. Instead, they drew attention to a legitimate flaw in the technology - and the only damage done was to the egos of Marconi and Fleming.

Fleming continued to bluster for weeks in the newspapers about Maskelyne's assault being an insult to science. Maskelyne countered that Fleming should focus on the facts. "I would remind Professor Fleming that abuse is no argument," he replied.

In the present day, many hackers end up highlighting flawed technologies and security lapses just like Maskelyne. A little mischief has always had its virtues.

Paul Marks is senior technology correspondent for New Scientist

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.

LightSquared and GPS interference.

LightSquared is a company that plans to provide a wholesale, nationwide 4G-LTE wireless broadband network that includes satellite coverage. LightSquared plans to combine existing mobile satellite communications services with a ground-based wireless communications network that uses the same L-band radio spectrum as the satellites.

However the signals for the LightSquared base stations will be transmitted on a frequency immediately adjacent to those used for the existing Global Positioning System (GPS). A draft report suggested that 75% of GPS receivers would be affected by harmful interference when located 100 meters from a LightSquared base station. LightSquared are naturally upset that the draft report had been leaked and have stated that they plan to operate their equipment at lower power levels which would affect 10% of devices.

If I were certain of their intent to run lower power levels I would still find this to be an unacceptable situation. I'm positively sure that if the amateur radio community proposed to operate in a manner that caused harmful interference to 10% of GPS units we'd be shutdown so fast our heads would spin.

GPS receivers, while not falling under the same category as emergency radio systems, are none-the-less an essential service for the smooth running of society. GPS has integrated itself into almost every portable electronic device and are used for much more than just navigation. Allowing LightSquared to continue without serious real world testing would be the worst way to find out how essential GPS had become and just how much it would cost to have it disrupted. More details are available on the website of the National Executive Committee on Space-Based Positioning Navigation and Timing

Pedestrian mobile and the magnetic loop with VK3YE

I've been using a 40M magnetic loop antenna for a while now and have been impressed with the low noise and high performance, especially considering its stuck in the middle of my garage!

I'd been thinking about a smaller loop that could sit in the attic with a remote tuner but had been put off by the critical requirements ... minimal dc resistance etc.

Now I have seen Peter and his portable loop I may have to reconsider brewing something up and giving it a shot. I'd like it to handle a bit more than 5W but that should be achievable with parts I already have in the junk box.

Old Time Radio (OTR) at Archive.org

When tuning across the AM broadcast band I'm often reminded that there is little left but sports radio and talk shows. I'm not particularly against either but I remember that in the past there was a lot more to pick from. With this in mind I have been looking around the Internet for a source of old time radio and found an excellent storehouse at archive.org.

I noticed while talking with friends that not too many people know about archive.org or assume its only used to hold podcasts. Nothing is further from the truth.

Take a look at  for an excellent collection of old time radio shows and once you've had your fill there, take a look at http://www.archive.org/details/movies and the video archives.

For a quick taste click the play button below and listen to Strange Tales.

Tales of the strange and bizarre, the weird and the wicked. Stories not necessarily of the supernatural, but of the unnatural

(If the player doesn't appear you may need to go to http://www.archive.org/details/oldtimeradio and listen to the radio show there)

Quick Iambic keyer using the Arduino micro-controller

With the multitude of inexpensive development boards like the Arduino it has become possible to add micro-controllers to just about everything. Projects that previously required custom designed circuits are now implemented by connecting to the input and output ports on a development board. Programming has become easier as well due to the development of simple and efficient software with libraries of sample code to modify and reuse for your own projects.

Costs have fallen dramatically with the development board featured below selling for approximately $30. At that price it could be the heart of automatic antenna tuners, rotor controllers or a keyer as shown below.

In the article link here: http://www.robotmotion.gr/robotmotion/Projects/Entries/2011/12/1_Iambic_keyer_with_Arduino.html

Dimitris Sapountzakis quickly home-brewed a set of touch paddles from spade connectors and perf board. 

Touch paddles made from spade connectors and perf board.

Once connected to the Arduino micro-controller he was able to use those inputs to control they keyer code he wrote. Because the logic is in software rather than hardware he could add automatic ID, contest modes or practically any any other function as simply as changing a few lines of software.

With micro-controller prices being as low as they are now we may start to see a renascence in home-brewing and kit building. Much as ham radio kits educated an earlier generation, economical micro-controllers may allow this generations an avenue to experiment, design and create tomorrow technology.

Considering a small HF antenna? You have to read this ...

I came across this explanation of the limitations of stealth/small antennas by Dan Zimmerman, N3OX. He has provided the best explanation of the physics behind 'short' antennas that I have seen so far.

This should be required reading for anyone considering one of the stealth antenna designs such as the Tak-tenna, Isotron or Crossed Field Antennas.

I hope Dan won't mind me copying his explanation from eHam.net. It is worth your while to head over to his web site and see some of his home brew antenna projects, there are excellent explanations provided as well as the thinking that went into each design.

Once you've had a read below go on over to: http://www.n3ox.net/ and take a look at Dan's website.

"In theory, a short antenna can be made efficient enough to compare very well to a full size version, but the tradeoffs (lower impedance, narrower bandwidth) are inescapable and you need to address them carefully to make it work well in practice" And the *most important thing* for hams who need small antennas like KB3HJK does is to never forget that those tradeoffs are fundamental. In order to radiate a certain amount of RF power into the universe with a short dipole, you *have to increase the current* flowing along the straight bit many times over what has to flow in a half wave dipole. If you make a very short/small antenna and want to *radiate* the same amount of power, that *requires* a much higher current flowing in the radiating part of the antenna, period. In order to pump more current through the antenna without causing significant losses, you have to reduce the loss resistance significantly compared to a big antenna. And an antenna that needs lots of current to radiate a given amount of power is said to have a "low radiation resistance" The power lost to heat in an antenna is basically I^2*Rloss (the antenna current squared times the loss resistance) The power radiated is I^2*Rrad (current squared times radiation resistance). So what does this have to do with bandwidth? Well, a couple of things. One is that when you make an antenna smaller and drive high currents in it, you make a LOT more electrons slosh back and forth in a small physical space. To focus on a short cap hatted dipole, there's a LOT of magnetic field caused by the very strong current (lots of electrons per cycle) flowing through the horizontal dipole part, and there's a LOT of electric field caused by lots of electrons piling up on the capacitance hats, first one and then the other, as the RF cycle progresses. A capacitance hat charges up on one part of the RF cycle, a quarter cycle later, all those electrons are rushing at maximum speed toward the other hat, another quarter cycle later, they're piled up on the 2nd hat, and another quarter cycle later they're rushing back toward the first hat. Energy is exchanged between the electric field, largely between the hats and the magnetic field as the electrons are rushing through the horizontal conductor. Since everything is so compact, the electric and magnetic fields are very strong, and store a lot of energy near the antenna. But we also know something else... we know that the radiation resistance is very small, and to make the antenna efficient, we must reduce the loss resistance. So the *total resistance* is very low. The resistance is associated with the energy lost per cycle of RF. Some goes to heat in the loss resistance, some goes to radiation, "dissipated" in the radiation resistance. But if you compare the energy *stored in the fields around the antenna* vs. the energy *lost per cycle*, you find that there's a lot of energy stored vs. how much is dissipated in the radiation and loss resistances. The strong fields make the stored energy high, the low resistances make the dissipation small. So the antenna is very "high Q." If you cut power to a very high Q antenna, it will ring down for a relatively long time as the stored energy is damped by the dissipation into loss and radiation. But we know from other circuits that high Q resonant circuits are very sharply tuned, and a small antenna is no exception. It has a very narrow bandwidth over which you can slosh current back and forth effectively in a resonant way. Since the radiation resistance and the stored energy in the fields is fixed by the size and shape of the antenna, the only way to broaden the response of a certain size antenna with fixed tuning is to add losses!!! This is fundamental, and will steer you away from very small, broad bandwidth antennas if you keep it in mind. You absolutely, positively must give up bandwidth to keep efficiency at small size. This is why the very best tiny antennas will all be motor driven. Magnetic loops and mobile screwdriver antennas with capacitance hats are two great examples of how to get around the narrow bandwidth problem. Sure, the antenna is 10kHz between the 2:1 SWR points, but if you can tune that 10kHz anywhere you want between 5 and 21 MHz, who cares? But there's even a point where motor drive doesn't save you. There's even a point where superconducting antennas don't save you. There's a lower limit that few talk about (except a few crazy magloop guys who come close to running up against it) If you make a very very tiny, extremely low radiation resistance antenna and you stamp out almost all the losses by welding together huge conductors, your antenna's bandwidth could become so narrow as to not pass even a SSB signal. ;-) You'd actually roll off your audio if you had a 1kHz wide magnetic loop and could make the tuning stable! But this is the basic fact you need to remember when antenna shopping. Quite small antennas should be easily retunable in small steps across a ham band, otherwise they are required to be *quite* lossy to give good SWR bandwidth. No matter what any manufacturer says, a tiny antenna needs to be VERY small in bandwidth for it not to be lossy. And KB3HJK, as far as that particular HF-p antenna goes? It's nearly impossible to know exactly but I expect that since it covers 200kHz of 40m with no retuning and is only 10 feet long, it's probably going to be about 1% efficent. For comparison, I built a 40 foot long 40m dipole with a loading/matching coil at the feedpoint that should have been about 80% efficient (-1dB) and was about 70kHz between the 2:1 SWR points. End loading could improve that, but the HFp isn't end loaded. If you really need to get on 40m better than you have been in the sort of 3-10 foot antenna class, your next antenna should have a motor. Or if you're worried about feedline radiators because you can put the antenna 20 feet up on a pole, just go ahead and make the pole the antenna instead. N0LX has some interesting voltage fed "loaded end fed half waves" on his website, and they actually model reasonably well. And even a Tak-Tenna type antenna is maybe OK, the problem with them is that there's NO REASON to use a 30 inch antenna on 40m. It's too short. Do the same thing but make it 15 feet long and you'll be much better off. 73 Dan