Crystals Go to War - 1943

One of the things that always fascinated me about radio was the ability to take discrete components and craft something that could pluck invisible radio signals out of the air. Once I learned more about electronics, some of the magic was replaced by admiration for the many generations of engineers and experimenters that had developed the radio art. Until recently, the theory behind crystals had not solidified (crystallized?) in my mind and so they remained one of those "mysterious devices".

The following film, like most produced during WWII, is a thorough explanation of the history and technology behind radio crystals. It was produced at a period when crystals were instrumental in securing reliable communications between military units, saving lives and coordinating the moment of supplies, troops and equipment.

I hope you'll find it as interesting as I did.

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.

Morsemail and LCWO.net

The time has come when I can't put off learning Morse code any longer, With an interest in vintage amateur radio and the impending restoration of a Heathkit AT-1 I'm going to need to use CW sooner or later.

So I have been checking out resources for learning Morse code and stumbled across two that really intrigue me.

The first is LCWO.net, a web browser based Morse code learning tool that is usable on any internet connected computer. It is available free of charge and there is no software to install. LCWO.net keeps track of where you are in your lessons and where you need to concentrate your effort. The Koch method is the primary tool available but they also offer code group practice, callsign and plain text training modes along with a service to convert text to Morse MP3s for download and use offline.

Once you are on the way to CW proficiency and want to communicate with others you can always fire up a rig and get on the air ... What if you don't have a rig or need a confidence boost before 'going live'?

Well, you could always send Morsemail using the Morsemail client from http://brasspounder.com:8873/.

Morsemail is, "A simple text format that encodes mark and space times to make it possible to send Morse coded messages via email" but a recently added feature allows for QSOs using a internet repeater hosted on brasspounder.com. You can use a mouse or actual key wired to the mouse or joystick buttons to send CW which can be emailed or sent through the repeater live.

Now I just have to carve out the time to sit down and use these resources!

Heathkit's first amateur transmitter - Heathkit AT-1

The Heathkit AT-1 represents the commercial embodiment of the simple Master Oscillator Power Amplifier (MOPA) transmitter using a crystal controlled 6AG7 oscillator plus a 6L6 final output tube.

Although it was possible to design and build a simpler transmitter, the goals of output power and stability could become mutually exclusive when trying to operate with only one tube. For a novice class license holder of 1951 the Heathkit AT-1 represented a solid performing rig that would be relatively easy to construct and operate.

The Novice remained the primary entry license until the Morse code requirement was eliminated for Technician licenses in 1990. On HF it permitted code transmissions only, with a maximum power of 75 watts, (input to the transmitter's final amplifier stage) on limited segments of the 80, 40 and 15 meter bands.

For $29.50 and the loan of a few tools you could get some use out of that new novice license

The earlier MOPA circuit from the ARRL handbook of 1941 below shows a layout remarkably similar to the circuit of the AT-1 although it is designed for plug in coils rather than the band-switching arrangement of the later Heathkit transmitter.

MOPA transmitter using a 6L6 and an 807 as the power amplifier (ARRL Handbook 1941)

For a little added complexity MOPA transmitters generally offered better stability of frequency and keying waveform than single tube crystal controlled or self exited rigs. The straight forward design of the AT-1 should have looked familiar to novice class hams after studying the ARRL handbook or other radio publications.

Heathkit AT-1 Circuit diagram showing band-switching arrangement and link coupled output

Once the novice had upgraded his license the AT-1 could be expanded by the addition of the Heathkit VF-1 variable frequency oscillator to allow transmission on any frequency within the allowed band.

The Heathkit VF-1 Variable Frequency Oscillator

The VF-1 covered 160-80-40-20-15-11-10 meters and used an OA2 voltage regulator tube to provide a stable voltage for the oscillator. Ceramic coil forms, solid construction and high quality components were used to help increase stability.

It was recommended that to correctly couple an antenna to the AT-1 you would use an antenna coupler such as the Heathkit AC-1 which also included a low pass filter.

The Heathkit AC-1 Antenna Coupler. Designed to attach to a single wire by the insulated post on the front panel.

Heathkit AC-1 Antenna Coupler circuit diagram

Although Heathkit did not produce a AM modulator for the AC-1 there is provision for modulator connection on the rear panel. The earlier ARRL manuals have several suitable circuits for modulators that would work with the AC-1. Most functioned by driving a modulation transformer with the output from an audio power amplifier. The secondary of the modulation transformer would be carrying the DC plate supply for the power amplifier tube plus or minus the instantaneous voltage of the audio waveform. By changing the plate voltage to the final amplifier tube the radio frequency output would be controlled by the amplified audio frequency resulting in amplitude modulation.

Virtual Tour of W1AW, the Hiram Percy Maxim Memorial Station

Virtual W1AW Tour on Sunday, February 12 at 5 PM EST (2200 UTC)

Join W1AW Station Manager Joe Carcia, NJ1Q, on a virtual tour of W1AW, the Hiram Percy Maxim Memorial Station, the Amateur Radio station at ARRL Headquarters in Newington, Connecticut. Carcia will lead this tour via a live webcast on . Anyone with an Internet connection will be able to watch the tour here.

W1AW - The Hiram Percy Maxim Memorial Station

"We want viewers of this live Internet tour to feel as if they are actually at W1AW," Carcia explained. "If you came to W1AW in person, you would see the same things that we are going to show on the virtual tour: The three operating stations, the W1AW workshop, the transmitter racks that we use to send out our bulletins and use for the code practice transmission, the control console and Old Betsy, Hiram Percy Maxim's personal spark gap transmitter."

Al Petrunti, KA1TCH, of the New Day Group, will follow Carcia as he leads viewers through the station. ARRL Staff members, including Media and Public Relations Manager Allen Pitts, W1AGP, and Chief Operating Officer Harold Kramer, WJ1B, as well as local television weatherman Geoff Fox, K1GF, will also be on hand at W1AW during the tour.

"Hams around the world know of W1AW, and thousands have made contacts with this impressive station -- but most hams never get to see it," Pitts said. "Thanks to Al Petrunti's group, we hope that folks enjoy seeing what's at the other end of the signals. As in all live broadcasts, you never know just what might happen. We invite you to join us." Pitts is producing the live web tour.


From the ARRL Letter, available at http://www.arrl.org/arrlletter?issue=2012-02-09

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.

ARRL President Kay Craigie, N3KN presents an insightful and inspiring talk about Amateur Radio

Lately I have been giving a lot of thought to the notion that, as a amateur radio operator, I should be engaged in this or that activity ... should volunteer for something ... should be building equipment ... should be operating more ... well, you get the picture. I enjoyed the following video because it highlighted the variety of experiences in amateur radio and how each has value to the community in its own way.

If you talk to any group of ham radio folk (or read through a ham radio publication) you'll always run the risk of feeling that somehow you're just not doing enough stuff and that you're not holding up your end of the deal. The FCC made allowances for you to operate on several bands of frequencies which are set aside for amateur radio use ... you really should be using them right?
The answer to that ... as far as I now think ... is yes, and also maybe. To be perfectly honest I do enjoy getting on the air from time to time and making contacts, usually digital as I don't seem to have an ear for picking out SSB voices from the noise. However ... there are other things like vintage vacuum tube equipment, experimenting and the history of ham radio technology that I enjoy more.
I came to realize that, much like genetic diversity, a ham radio club that has members interested in a wide range of things could potentially be more robust and offer a greater service to the community and its members. There is one critically important caveat here however and it has been the downfall of several special interest clubs in the past. In order for a club with members having diverse interests to survive and thrive there must be a significant amount of tolerance shown by each and every member. We are both united by a common interested and made unique and interesting by the variety of ways that common interest is manifest.
If you don't operate QRP then stop a moment and talk to someone who does, if you only operate CW then chat to someone who operates digital modes or phone. Different disciplines can always benefit from a little cross traffic and you may be amazed at what you learn!

Crystal oscillators and radio transmitters

Since the very early days of ham radio, crystals have been used to provide stable and precise source of transmitter frequency control. In addition, they have also been used in filter circuits to control bandwidth and prevent the reception of unwanted signals.

A quartz crystal from my collection. It is a FT-243 style holder, suitable for use in a vacuum tube transmitter.

Early transmitters used variable capacitors and inductors to create a self resonant tuned circuit. One drawback to this simple design is that it could change frequency depending on temperature, humidity, supply voltage or the proximity of conductive objects (Including the operator!). Shielding and temperature compensated components helped to reduce frequency drift but it was still common practice to follow the transmit frequency of another operator as both your receiver and his transmitter drifted.

The QRP sized AMECO AC-1. Using a single 6V6GT as oscillator and output tube.

From 1951 holders of the Novice class license were only permitted to use crystal controlled transmitters limited to 75 Watts. They were also further restricted to a small segment (3.700 - 3.750 Mc) in the 80M band. This had the side effect of popularizing simple crystal controlled transmitters using either a single vacuum tube as both oscillator and output amplifier or transmitters using one tube for the master oscillator circuit and one for the power amplifier, also known as MOPA (Master Oscillator, Power Amplifier).

The Heathkit AT-1 transmitter. One oscillator tube 6AG7 and one power amplifier tube 6L6.

In either case a crystal was required for every frequency you wanted to transmit on and few new hams could afford more than a couple of crystals for their transmitter. Often you would call CQ and listen up and down the band for someone replying to your call as the other operator would not necessarily have the same frequency crystal as yours.

But how do crystals work?

From Wikipedia:

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them became known as "crystal oscillators."

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to tens of megahertz. More than two billion (2×109) crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.

An electric current causes the quartz crystal to deform.

When a crystal of quartz is properly cut and mounted, it can be made to distort an electric field by applying a voltage to an electrode near or on the crystal. This property is known as piezoelectricity. When the field is removed, the quartz will generate an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like a circuit composed of an inductor, capacitor and resistor, with a precise resonant frequency.

Deforming the quartz crystal causes an electric current to flow

Quartz has the further advantage that its elastic constants and its size change in such a way that the frequency dependence on temperature can be very low. The specific characteristics will depend on the mode of vibration and the angle at which the quartz is cut (relative to its crystallographic axes).[8] Therefore, the resonant frequency of the plate, which depends on its size, will not change much, either. This means that a quartz clock, filter or oscillator will remain accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations.

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

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

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

Bad news for kit builders in the EU

G4ILO Writes ...

I’m not the first blogger to mention this item of news but it is certainly one topic that I could not allow to pass by without comment. According to the IARU Region 1 website, the EU Commission will be revising the EMC Directive and removing the exemption of amateur radio kits and modified equipment from its provisions. Products that are currently exempted would be subject to inspection and certification, a process which would make the production of kits hopelessly uneconomic. It would also potentially spell the end of home building and modification and prevent the importation of kits from the USA and other havens of relative sanity. No, this isn’t one of my April 1st spoof stories released from the Drafts folder by mistake!
I would hope that the IARU, the RSGB and other European amateur radio societies will make urgent representations to the EC to stop this proposal. But this is just one scary example of why I and many other like-minded people feel that we in the UK would be better off out of the European Union.
In fact, most of Europe would be better off without it in my opinion. Could somebody explain why, at a time when European governments are supposed to be cutting back on public expenditure, they continue contributing billions every year (only recently having voted an increase – the UK alone contributes £51 million per day) in order to fund this unelected and unaccountable Commission to employ people who live in cloud cuckoo land to produce unwanted, unnecessary and unasked-for legislation?

Original Article

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.

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

Learning morse code? This is a great resource!

The Straight Key Century Club has made available classic books in morse code. HG Wells, "War of the Worlds" initially starts out at 10 words per minute increasing one word per minute each chapter until the last chapter is sent at 36 words per minute.
Many classic books are available at http://www.skccgroup.com/learn/learn.php in mp3 format.
Not having made much progress on learning CW myself this may be the motivation I need to start, I've never been able to resist a good yarn by HG Wells.

Wartime Radio: The Secret Listeners

This is a great documentary filmed in 1979. It tells the story of amateur radio operators intercepting German Naval messages and the development of secret listening posts in the UK. Lots of good footage and history along with interviews with historic personalities.

Illustrated with archival film and photographs, as well as interviews with those involved, the documentary traces the evolution of civilian involvement in radio-based intelligence during both world wars.

It was the tireless work of amateur radio enthusiasts during World War I, that initially convinced the Admiralty to establish a radio intercept station at Hunstanton. Playing an integral role during the war, technological advances meant that radio operators could pinpoint signals, thus uncovering the movement of German boats, leading to the decisive Battle of Jutland in 1916.

Wireless espionage was to play an even more important role during World War II, with the Secret Intelligence Service setting up the Radio Security Service, which was staffed by Voluntary Interceptors, a band of amateur radio enthusiasts scattered across Britain. The information they collected was interpreted by some of the brightest minds in the country, who also had a large hand in deceiving German forces by feeding false intelligence.

New project - Heathkit SB-101

I've recently been presented with a Heathkit SB-101 transceiver, Heathkit SB-600 speaker and Heathkit HP-23A power supply courtesy of Philip KJ5OW of the Katy Amateur Radio Society.

The SB-101 is a hollow state rig, the only solid state components being a few diodes. It uses the well known, and fortunately fairly common, 6146 output tubes in the finals.

The manual is available here : Heathkit_SB101_Manual

Heathkit SB-101 Transceiver

There looks to be a little work required before this rig is put on the air, a few resistors have cracked for reasons unknown and the rubber belts need replacement in the load and tune controls. It is something worth taking time on as the SB-101 is a well regarded rig that is still a strong performer today. There have been some modifications made to support an external linear master oscillator (VFO) which will need to be looked at but are probably fine as they stand.

I pulled my Heathkit HD-1410 keyer out of storage and was pleased to find it was the same color and style, matching the SB-101.

Heathkit SB-101 transceiver, SB-600 speaker, HP-23A power supply and HD-1410 electronic keyer.

Specifications:

Year of Manufacture: 1967-70 (Improved SB-100[1965-7])
Bands: 80 - 10 (500kc) (2 Mhz on 28-30 mhz)
Modes: CW & SSB
Power: 180W PEP SSB & 170 input CW - 6146 Output Tubes
Frequency Control: LMO- Linear Master Oscillator (Like PTO)
Selectivity: 6 Pole filter 2.1kc @ 6db down (Accessory CW filter 400hz)
Contstruction: Aluminum Chassis & Cabinet-Printed circuit board wiring
Keying: PTT and VOX voice operation, VOX with sidetone for CW
Power Supplies: AC or DC power supplies availiable
Microphone: High Impeadance Desk or Mobile Microphones availiable.
Frequency Control: Local LMO/Xtal, Remote VFO/SB-640 w/Mod

Accessories: SB-200 Linear Amplifier, SB-500 2mtr Xvtr, SB-600 Speaker, SB-610 Monitor Scope, SB-620 Panadapter, SB-630 Station Console, SB-640 Remote VFO & SB-650 Digital Read-out.

Features: Easy to operate, TX & RX circuits track, RX RF Preamp, Easy to calibrate and read dial calibration, Two-Tone Green wrinkle paint, Switched Metering, Construction Manual very comprehensive.

Heathkit Transceiver Resources:

• Heathkit HW & SB series parts : http://www.ultrawebb.com/OHP/index.htm
• Heathkit HW & SB series modifications : http://boatanchor.com/Heath/HW101MOD.PDF
• Digital Dials for Analog Rigs : http://www.aade.com/
• Dialcord replacement for o-ring drives : http://nrwilliamson.tripod.com/dialcord.jpg
• General HW & SB repair information : http://www.qsl.net/k5bcq/102/102.html

Latest restoration project - Espey R-366/TRR-5 Radio Receiver

The Espey R-366/TRR-5 is a general purpose receiving set designed for use as an entertainment unit or auxiliary communications receiver. The receiver is a manually tuned, 16 tube superheterodyne. It has a tuning range of 540 to 30,000 kc in five tuning bands and receives either CW or voice signals.

It is similar to the Scott receiver AN/SRR-3 of the same period and produced under Contract NObsr-43229 dated 15 March 1949.

A user manual is available here : ANTRR5_INSTRUCTION_BOOK

The front panel as it originally looked.

The front panel once it had been cleaned.

First page in NAVSHIPS describing AN/TRR-5 and performance specifications.

Detailed shipping information for AN/TRR-5 receiver.

From the Antique Radio Forums :

Most of them were purged via DRMO in 1968-1973 and I only saw small numbers of them trickling through the system so I am guessing they were made in only a small quantity. None of the ones I have run across have had cabinets and all were in pretty atrocious condition. I vaguely recall the processing papers showing the equipment had come back from Vietnam, Guam, S. Korea and Japan.

Geoff Fors - WB6NVH

If you have any information regarding these receivers please leave a comment. If you have a R-366 of your own please let me know the serial number in the comments!

R-366/TRR-5 serial number registry:

1. #623 : KF5CZO - Owen Morgan
2. #050 : AE5VB - Hugh Coleman
3. #132 : W5AMI - Brian Sherrod
4. #591 : KC9KUH - Brian Love : (Compliance plate missing)
5. #290 : KC5IIE - Chris Krug (Update 01/11/2012 : Sold to W5XTL - Jeramy Ross)
6. #653 (Sold on Ebay, spotted by Brian KC9KUH)
7. #251 (Sold on Ebay, spotted by Brian KC9KUH)
8. #340 (Sold on Ebay, spotted by Brian KC9KUH)
9. #468 Jeff Wewers
10. #140 Gilbert Mendez
11. #097 James Starling

Using the formula N=m(1 + k ^{− 1}) − 1  from the german tank problem where m is the largest serial number observed and k is the count of serial numbers we see that the current estimated number of R-366/TRR-5 receivers produced is N=653(1+11 ^{− 1}) − 1 or approximately 711.

After bringing this receiver up on a variac to reform the filter capacitors I monitored the power usage and found it to be in line with the users manual @ approx 125W.

Audio is great due to the push-pull output stage and either a 6 ohm or a 600 ohm speaker can be used, both impedances are available on the rear connectors.

Readout seems accurate and the VFO is stable after just a few minutes warmup. Tuning the HAM bands is fairly touchy but this is really an AM rig by design.

Serial number 623 of how many? This seems to be a rare radio but I have heard of at least 4 other people with the R-366.

The bandchange is accomplished by rotating the circular turret. Each of the five bands has a complete set of discrete components in its sector of the drums.

Military amphenol right angled connectors. The three pin connector is 110V power in and the four pin is the 6/600 ohm speaker connector.

I was fortunate enough to be given period style military connectors for these sockets. Both neutral and active lines are fused on the power input circuit however I made sure to wire the active line to the power switch side for safety.

The receiver chassis slides out on roller slides for servicing and inspection. The full circuit diagram is also on the band change turret cover ... a thoughtful addition!

The only modification I can find is the antenna connector. Its been replaced with a SO-239 bulkhead connector for convenience. Personally not something I would have done myself but it makes life easier so I'm not complaining.

An unmodified antenna connection from another Espey R-366