The 3D printed Blackriver 4x5 View Camera

To start in wet plate photography you need the basic chemicals, plates and a working camera. The size of the images you want to make determines the size of the film/plate holder and ultimately the size of the camera. 

I thought 4x5 inches would be a good size to start as the plates & chemicals required are less expensive and I could afford to make more mistakes! ( I was assured there would be many while I learnt, they weren't wrong )

While there are deals to be found for large format camera if you want one straight away they can cost from $300 to, well ... as much as you would like to pay.

I didn't really like the sound of waiting around till I found a deal so I paged through Thingiverse till I found the BlackRiver 4x5 View Camera v1.0

There were a lot of parts that had to be printed accurately but I decided to give it a try.

 

My BlackRiver 4x5 View Camera

There were some mechanical parts which had to be purchased but they were also
used in 3D printers and were available at a modest price. Binder clips were used to secure parts together which might need to be changed or rearranged and standard metric nuts and bolts completed the build.

To save expense with the lens I acquired a Russian lens via Ebay without a shutter since the exposure times with wet plate are long enough that they can be timed by hand using the lens cap to uncover and cover the lens.

My 4x5 plate holder

Since this camera was designed for film I needed a plate holder that would suit the thicker aluminum or glass plates I planned to use. 

Again Thingiverse came to the rescue and provided plans for a 4x5 plate holder, after a few modifications to improve its light-tightness its been working well.

It turned out that the 3D printed dark slide could not completely block full sunlight and I ended up using a trimmed down Graflex dark slide

Wet Plate Photography

 I've been interested in photography since I was a teenager in highschool and started developing my own film and prints. Being able to manage the process myself freed me from the dependency and cost of commercial processing. There remained the matter of buying film and paper ... so I was still tied to the local photographic supply store.

Recently, and what feels like a lifetime later, I've discovered the historic process of wet plate photography and freed myself from photo labs and photographic supply stores all together

The wet-plate photographic process originates in 1851 and largely replaced the
previous Daguerreotype process which relied on mercury vapor to develop the plates. 

The most common wet plate process, ferrotype, involves coating a black metal plate with a film of collodion in which bromide and/or iodine compounds are added. Its then placed in a bath of silver nitrate where it develops light sensitive silver halides. 

While the plate is still damp it is placed in a camera, exposed to the view through the lens and then developed before the plate has dried. Once developed, the image is fixed with a "hypo" solution to remove any remaining light sensitive compounds and finally dried and coated with a varnish to protect the layer of metallic silver which forms the image.

Unlike the more modern film negatives, this process results in a positive image made up of bright metallic silver deposites on a black background. The lightest part of the original image producing the largest deposits of silver on the plate while dark areas remain black as the surface of the plate.

 

 

Originally tin plates would have been used which were coated with Japanning (A black lacquer containing asphaltum) but now most photographers will use trophy aluminium, plates coated with a black film which can be laser etched. They serve perfectly for wet plate photography and are of a very consistent quality. 

The resulting photograph is unique to the wet plate process. The emulsion is only sensitive to UV light, blue ... and to a small extent green light.

In addition to recording light differently to modern black and white film, the image is reversed from left to right. Your face will appear the same way you view it in a mirror.

3D modeling and printing

 

One thing I'm thankful occurred in my lifetime has been the widespread use of 3D printing at a cost-point that is accessible to hobbyists and makers. Its given many people the ability to go from a design in their head to an accurate physical model in hours. Alternately, designs can be shared online between those who have the resources to create technical designs and end users who can simply download a design and print it on their printer (or one in a library, etc)

As global health emergencies have impacted our way of life, the ability to quickly produce needed articles of PPE equipment or lifesaving hardware locally has been invaluable.

I've participated by 3D printing articles of PPE equipment and donating them to local medical facilities. I've been able to print designs that were created half a world away or practically next door, all shared through repositories like www.thingaverse.com 

In addition to downloading designs for 3D prints, I've been learning to model in 3D and create my own. A variety of online tools make this fairly simple and I've been able to make cases, test stands, 3D printer improvements and tools for other hobbies. Hopefully I'll have the opportunity to do more with this skill and sell some of the things I've created on Ebay and other online vendors.

Vintage and retro computers

 I'm not sure if this should be classed as technology or nostalgia. When I first started working with computers I was fortunate to encounter CP/M systems and some early UNIX systems ... I never forgot how simple and efficient those systems were and how much you could accomplish with modest hardware. Entire companies running on multiuser systems with no more CPU power than an Intel 486 CPU (Does anyone remember those?)

In order to restrict the collection I've focused on systems that were available around 1975, they're the same age as me.

MITS - Altair 8800: "The Altair is widely recognized as the spark that ignited the microcomputer revolution as the first commercially successful personal computer."

More importantly it has blinking lights and switches on the front panel, lots of lights and switches!

Real computers let the operator halt the system and patch programs in binary then restart the system where it left off.

 

CP/M existed before MS-DOS and, if you've ever used DOS, you'll find that its eerily similar ... almost as it Bill Gates copied most of the concepts from other earlier operating systems. 

In any case, CP/M has appeared in many different versions and even included multi-user variants. It ran on a large variety of hardware with different architectures and abilities. Code from one version of CP/M can be recompiled and ran on another.

I've enjoyed running favorite programs from my youth such as the original Infocom text adventures and programming in COBOL, FORTRAN and BASIC. You can even run simple programs programmed in binary on the front panel ... as long as you have the patience to toggle all those switches!

The picture to the right is my reproduction Altair 8800 system with DEC VT-220 monochrome serial display.

 

Digital Equipment Corporation - PDP 11/70: "The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corperation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, making it one of DEC's most successful product lines. The PDP-11 is considered by some experts to be the most popular minicomputer."

 

The reproduction system I have was supplied in a kit and powered by a Raspberry Pi. The assembly was fairly easy, the most time consuming part was installing and aligning the switches and LEDS. The result was rewarding as it exactly resembles a scaled down version of the PDP11/70 with all the peripherals emulated that were available for the systems. I've yet to set this system up in a permanent home but I have another DEC VT style terminal for it to connect to and a DEC LP-50 line printer to round out the installation.

The PDP11 system allows me to run classic operating systems from the time such as RSTS and RSX11M. 

There are good development environments for FORTRAN and COBOL and DECs own variants of BASIC which are extended with additional function that hook into database like systems and external APIs. 

It can run as a singer user system or multiuser and it was this latter mode that allowed the PDP systems to run in businesses and universities, serving many users at once while running physics simulations, word processing, teaching programming or running administration systems.

Quicklook - Home Network Version 2

Raspberry Pi 4 3D printed case

 The latest version of my home network was built in order to learn more about Kuberneties and clustering. It had the added advantage of unifying the processor type (arm64) across the network making automated administration slightly simpler. 

The primary core is a stack of Raspberry Pi 4 boards in custom 3D printed cases, loaded into a custom 6 inch (rather than 19 inch) rack. 

 Nocturna low speed fans were used to assist with cooling and airflow.

 

To store the various media files, backups and documents I decided to go with a clustered storage solution (clusters again!). 

I tried Ceph but found that the memory requirements exceeded the available memory on the ARM SBC boards I attached to the disk drives (Odroid HC2). 

I ended up using MooseFS and this worked out to be a good choice as MooseFS has been extremely stable both in operation and recovery from drive failures.

All systems run from 12V DC or 5V DC and will eventually run from a battery bank recharged by solar panels. 

Each 4TB disk in the storage cluster is housed in a heatsink and attached to an Odroid ARM64 single board computer. In effect this gives each drive its own 1GB network interface and an aggregate 8TB of IO bandwidth in ideal circumstances. 

To improve cooling I 3D printed cowls for each stack of 4 drives and installed low speed nocturna fans. Next step will be connecting the fans sensor lines so that it will gracefully shut down in the event that a fan fails.

I used the K3S Kubernetes distribution since it was optimized for smaller servers but still contained everything required for a full kubernetes stack. I've been able to run various workloads with no issues and run some of my permanent applications on K3S now. Its been a good learning experience, even if its a bit of an overkill for self hosting home applications.

Getting started with the ESP8266, NodeMCU and Wemos D1 Mini

After a long, work induced, hiatus away from electronics I have started up again with the ESP8266 serial of WiFi connected microprocessors. In the past I had been experimenting with sensor platforms based on an Arduino UNO and Ethernet shield. These were fine as far as they went but being tied to a wired ethernet cable made them less that portable.

I made the decision to switch platforms after trying WiFi solutions based on the CC3000 chipset tied to the Arduino UNO and being very disappointed by their reliability. I noticed that the Arduino development environment had started to support the ESP8266 chipset and initial reports seemed to indicate they ran for long periods of time without issues.

With more and more 3.3 Volts parts being made available on breakout boards, it also seemed like the right time to make the shift to a 3.3V microcontroller.

Initially I started with the NodeMCU development board which ran a Lua interpreter. This appeared to work fairly well but I am used to the Arduino development and programming with its implementation of C so I switched to the Arduino IDE. In addition there are many more hardware support libraries available in the Arduino environment, the vast majority of which run without modification of the ESP8266. The NodeMCU boards fit neatly into breadboards and are well suited for experimentation.

Fortunately I have side-stepped any issues with drivers for the on-board serial to USB chips by using Linux as a development environment. Unfortunately I can't offer any suggestions for other operating systems such as Windows or Mac OS/X.

My first project was a temperature and humidity sensor using the DHT11 sensor. Using the WiFi connection, through my home router, the sensor information was sent out to ThingSpeak every 10 minutes. After sending the MCU was put into deep sleep mode until another ten minutes had passed, at which point the MCU was reset and the cycle started again. The code I used for this is available for download here: thingspeak_data-logger.ino (Arduino 1.6.7)

Since I ultimately wanted to run the sensor from a rechargeable battery I needed to be able to read the voltage being supplied to the ESP8266. This function is built into the ESP8266 but it took some time to figure out the right incantation to get it to work. For the record this is documented below:

In the initial header of your project you need to specify "ADC_MODE(ADC_VCC);" to enable analog 0 (A0) to read VCC.
Once that is complete, in the main body of the code, you can read VCC using "float vcc = ESP.getVcc();" to read the current VCC*1024. Dividing by 1024 should yield a figure representing VCC in volts.

Using the NodeMCU with deepsleep I was able to power the sensor from a USB power-pack for approximately 20 days before the powerpack shutdown to protect the Lithium-ion batteries.

Later, cruising around the online Chinese supplyhouse AliExpress, I discovered a smaller form factor version of the ESP8266 breakout board that had a healthy collection of shields containing most of the electronics I was interested in. The Wemos D1 Mini is about the size of a postage stamp but still contains all the support electronics including serial-to-USB and 5V to 3.3V regulator.

When using the WiFi sensor code on the Wemos D1 Mini I have been able to run for at 15 days on the same USB battery pack before it showed any sign of discharging (three out of four battery level lights lit) so I'm assuming that the D1 Mini draws much less power in deep sleep and is therefore a better choice for battery powered projects.

For my own reference as much as anything I made a list of the currently available D1 Mini shields and the pins they use:

Shield Name	Device Type	Pin Used	Pin Definition
DHT Shield	DHT11	Pin D4	Data Out
DHT ProShield	DHT22	Pin D4	Data Out
OLED Shield	OLED using SSD1306 driver	Pin D1, D2	SCL, SDA
1-Button Shield	Momentary push button	Pin D3	Button
Relay Shield V2	5VDC Relay	Pin D1	Relay Enable
Micro SD Shield	Micro SD adapter	Pin D5,D6,D7,D8	CLK,MISO,MOSI,CS
ProtoBoard Shield	Proto Area	All Pins	Proto Area
Dual Base for D1 mini	Stack D1, shields side-by-side	Pins are duplicated

Important notes: You will need to use a modified library for the OLED display which is available here: SparkFun_Micro_OLED_Arduino_Library If you use the standard Sparkfun library you will not be able to display text.

I have an example of using the OLED shield to display sensor readings from the DHT22 available here: wemos_temp_display.ino (Using DHT sensor library from Adafruit V1.2.3)

I'm hoping that the Wemos D1 Mini and its accompanying shields will enable the quick prototyping of handheld sensor platforms that include wifi connectivity. My next project will involve configuring WiFi SSID, WEP keys and ThingSpeak API keys without having to connect to a computer with the Arduino IDE. Hopefully through the use of a captive portal and switching the ESP8266 into Access Point mode to allow configuration via a tablet of smartphone.

With any luck this information will help you make progress quicker that I did. This hardware is well worth investigating: A full set, including Wemos D1 Mini and all shields, is only going to set you back perhaps $30-$40 if you already have a computer to run the Arduino IDE.

One last thing ... Shipping from China to Texas has typically taken around 20-30 days when ordering from AliExpress. So, order everything you think you might need at once otherwise you are not likely to enjoy the wait while the additional shields you need take, literally, the slow boat from China.

NJIT's New Solar Telescope Unveils the Complex Dynamics of Sunspots' Dark Cores

From the New Jersey Institute of Technology newsroom ... 

Groundbreaking images of the Sun captured by scientists at NJIT’s Big Bear Solar Observatory (BBSO) give a first-ever detailed view of the interior structure of umbrae – the dark patches in the center of sunspots – revealing dynamic magnetic fields responsible for the plumes of plasma that emerge as bright dots interrupting their darkness. Their research is being presented this week at the first Triennial Earth-Sun Summit meeting between the American Astronomical Society’s Solar Physics Division and the American Geophysical Union’s Space Physics and Aeronomy section in Indianapolis, Ind.

The high-resolution images, taken through the observatory’s New Solar Telescope (NST), show the atmosphere above the umbrae to be finely structured, consisting of hot plasma intermixed with cool plasma jets as wide as 100 kilometers.
“We would describe these plasma flows as oscillating cool jets piercing the hot atmosphere. Until now, we didn’t know they existed.  While we have known for a long time that sunspots oscillate – moderate resolution telescopes show us dark shadows, or penumbral waves, moving across the umbra toward the edge of a sunspot – we can now begin to understand the underlying dynamics,” said Vasyl Yurchyshyn, a research professor of physics at NJIT and the lead author of two recent journal articles based on the NST observations.

Called spikes, the oscillating jets result from the penetration of magnetic and plasma waves from the Sun’s photosphere – the light-giving layer of its atmosphere – into the abutting chromosphere, which they reach by traveling outward along magnetic tubes that serve as energy conduits.  “This process can be likened to a blowhole at a rocky beach, where relentless onshore waves jet sea water high into the air,” Yurchyshyn said.

Sunspots are formed when strong magnetic fields rise up from the convection zone, a region beneath the photosphere that transfers energy from the interior of the Sun to its surface. At the surface, the magnetic fields concentrate into bundles, which prevent the hot rising plasma from reaching the surface. This energy deficit causes the magnetic bundles to cool down to temperatures about 1,000 degrees lower than their surroundings. They therefore appear darker against the hotter, brighter background.

“But the magnetic field is not a monolith and there are openings in the umbra from which plasma bursts out as lava does from a volcano’s side vents. These plumes create the bright, nearly circular patches we call umbral dots,” Yurchyshyn noted. “Sunspots that are very dark have strong magnetic fields and thus fewer openings.”

Compact groups of fast-changing sunspots create tension in their magnetic systems, which at some point erupt to relieve the stress. It is those eruptions that cause intense “space weather” events in the Earth’s magnetosphere affecting communications, power lines, and navigation systems.

“We had no sense of what happens inside an umbra until we were able to see it in the high-resolution images obtained with the world’s largest solar telescope. These data revealed to us unprecedented details of small-scale dynamics that appear to be similar in nature to what we see in other parts of the Sun,” Yurchyshyn said. “There is growing evidence that these dynamic events are responsible for the heating of coronal loops, seen in ultraviolet images as bright magnetic structures that jet out from the Sun’s surface. This is a solar puzzle we have yet to solve.”

Since it began operating in 2009, Big Bear’s NST has given scientists a closer look at sunspot umbrae, among other solar regions. It has also allowed them to measure the shape of chromospheric spectral lines, enabling scientists to probe solar conditions.

“These measurements tell us about the speed, temperature, and pressure of the plasma elements we are observing, as well as the strength and the direction of the solar magnetic fields,” said Yurchyshyn, who is also a distinguished scholar at the Korea Astronomy and Space Science Institute. “Thus we were able to find that spikes, or oscillating jets, are caused by chromospheric shocks, which are abrupt fluctuations in the magnetic field and plasma that constantly push plasma up along nearly the same magnetic channels.”

The study on umbral spikes was published in the Astrophysical Journal in 2014.

In a second paper published in the Astrophysical Journal in 2015, he is presenting another set of NST observations, taking a closer look at the sunspot oscillations that occur every three minutes and are thought to produce bright umbral flashes - emissions of plasma heated by shock waves.

The NST takes snapshots of the Sun every 10 seconds, which are then strung together as a video to reveal fast-evolving small explosions, plasma flows and the movement of magnetic fields. “We were able to obtain photographs of these flashes of unique clarity that allowed us to follow their development inside the umbra,” he said. Previously believed to be diffuse patches randomly distributed over the umbra, the researchers found their location is in fact not random. They mainly form along so-called sunspot umbral light bridges, which are very large openings in the sunspot magnetic fields that often split an umbra into two or more parts.

“Even more importantly, we found that umbral flash lanes tend to appear on the side of light bridges that face the center of the sunspot,” he added. “This finding is significant because it indicates that sunspot oscillations may be driven by one energy source located under the umbra. There are simulations that appear to reproduce what we have observed, which is very encouraging. We, as a community, are finally in the position to be able to directly compare the observations and the state-of-the-art simulation results, which is the key to making further progress in our field.”

To view more images, click here.

For further information, contact Tracey Regan at NJIT at tregan@njit.edu or 201-388-0232 or Craig DeForest, AAS/SPD press officer, at deforest@boulder.swri.edu or 303-641-5769.

Ham radio attempts to fill communication gaps in Nepal rescue effort

A nice write-up outlining how Ham Radio has once again provided vital lifelines of communication to the people of Nepal.

Amateur radio has stepped in to fill communication gaps in Nepal, which is struggling with power outages and a flaky Internet after a devastating earthquake on Saturday killed over 5,000 people. Though 99 persons have ham licenses in Kathmandu, about eight use high-frequency (HF) radios that can transmit long distances, while another 30 have very high frequency and ultra high frequency sets for local traffic, said Satish Kharel, a lawyer in Kathmandu, who uses the ham call signal 9N1AA. The hobbyist radio operators are working round-the-clock to help people get in touch with relatives, pass on information and alert about developing crises.

Read full article at http://www.itworld.com/

If you have 8 minutes, take a look at the video below from MikesMovies. This shows the real life emergency net that was developed to help with Nepalese communications.

Lab grown quartz crystals: How its done.

Following up on yesterdays post regarding the manufacture of radio crystals from natural quartz crystals, I was able to find this video from the AT&T archives showing the relatively new, at the time, method of growing quartz crystals in the laboratory.

The video, produced in 1962, shows first the frustrating failures and ultimately the ability of Bell Labs staff to reliably produce the invaluable quartz crystals.

Very little of the technology we value today would have been possible without the hard work and perseverance of these early pioneers.

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.

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. 

Richardson "5" - 1925

I recently purchased a Richardson "5" TRF receiver and after bringing it home discovered somewhat disappointingly that, although in excellent condition appearance-wise, this radio is not going to play without a significant amount of work.

Although it was sold to me with the opinion that it did play, I think it more likely that it played at some point in the past ... although I'm willing to give the seller the benefit of the doubt.

The Richardson Radio Inc of New York seems to have appeared on the scene in 1925, lasting perhaps a year and then vanishing. The Richardson "5" features neutralization but doesn't appear to mention licencing that technology from Hazeltine so this may have had something to do with their short life.

The chief problem seems to be the wiring which is soldered in only a few places and otherwise consists of stakes or posts that have been pushed through the insulation of the wires in the same way that inexpensive garden lights are sometimes put together.

Given time, almost 90 years in this case, the poor contacts and gradually deteriorating insulation have done a good job in turning almost every connection into an intermittent connection. When I powered the radio up it was obvious that the two stages of audio amplification were working but touching any wire in the RF amplifier or detector sections just changed the quality of the noise in the headphones. I was never able to tune in a station or even see if the RF sections were working.

So, I have a choice. This radio can either be dust collector on the shelf and an example of how not to wire a set or I could re-wire it using proper soldered connectors which wouldn't be "authentic".

Not sure what to do exactly. Not that I will be diving into it any time soon, I still have the AK20 restoration to complete before I start anything else.

It didn't come with a speaker but I didn't find any evidence that Richardson Radio ever sold a loud speaker and the example at the top of the page uses a "Superspeaker Console" from the Jewett Radio & Phonograph Co.

The Richardson "5" uses a six volt "A" battery and "B" battery voltages of forty five and ninety volts. When running from the ARBE III supply I set the "A" battery voltage to five volts so there is little risk of burning the five 01A tubes too brightly.

All-in-all I would say that it is a handsome set that will look good on the shelf and may eventually be made to work again. It will be interesting to see what difference the neutralization makes to a circuit that is essentially identical to the AK20.

Atwater Kent - Model 20 : Important Documents

One of the first things I do once I have acquired a new "treasure" is to gather together all the information I can find and stick it in one place.

To this end, here is what I have found online and scans of some of the paperwork I have acquired. Most will be specific to the Model 20 but some may also cover other Atwater Kent radios:

Sadly I do not have a high resolution scan of the Model 20 log card which I believe is Form F 103, can you help?

This is Form F 194 which would suit a single dial Atwater Kent radio.

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

A small amount of cleanup may be required to print correctly on your printer.

Download the PNG file HERE (49MB)

At the right is the "Radio Log Cards and Important Instructions" envelope which was used to organize all the paperwork. This would typically be held in between the two clips inside the radio.

If you are wondering what those clips were used for, now you know!

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

A small amount of cleanup may be required to print correctly on your printer.

Download the PNG file HERE (57MB)

This is the back of the envelope so you can see the fold patterns and get an idea of how it was put together.

I plan to clean up these images and generate a pattern which can be printed out via a large format printer at a FedEx office or similar.

The pieces I have are too fragile to use and would crumble if handled more than a few times.

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

Download the PNG file HERE (56MB)

I have several of the loud speaker instruction sheets and they seem to be generic enough to suit any of the horn type loud speakers. As far as I know they all have a similar adjustment underneath and all users should heed the warning about connecting them to the receiver with the correct polarity.

As with all the images I have used full color images so you can see the original colors and then change it to black and while to increase contrast for printing.

The file is scanned at 600DPI and if printed at the same resolution it should be the same size as the original.

Download the PNG file HERE (54MB)

This is the Atwater Kent Radio Service Manual from 1928.

This manual covers from the Model 10 to the Model 52 including accessories such as the power units and loud speakers.

This manual was a pain to find so hopefully this will help some people out and ease frustration.

Download the PDF file HERE (8MB)





This is the Atwater Kent Radio Instruction Book Vol. 2 from 1925.

The instruction book covers the Model 10 through to the Model 24 and contains important photographs showing battery cables, battery boxes and other accessories.

Download the PDF HERE (14MB)








I'm looking for high resolution scans of the following two forms: F91A and F101 as shown in the picture below. If you have scans or can point me in the right direction I would appreciate it!

Atwater Kent Model 20 "Big Box" - 1924

Ok, you got me. This isn't technically an amateur radio blog post but I would argue that radio in the early 1920's was the pursuit of the amateur, the enthusiast and the tinkerer. The amount of crossover between commercial broadcast radio and amateur radio in those days was much greater than it is now. Anyway, that's my excuse ... but why the Atwater Kent Model 20?

The model 20 or AK20

Well, to make along story short, I found an example of this Atwater Kent model sitting in a flea market stall in Hot Spings Arkansas. It looked like it had seen better days but was fully complete including the five '01A' vacuum tubes. The owner wanted $200 for the radio and explained the better part was the included horn type loud speaker which was worth $150. The horn speaker looked to be in fairly bad shape and lacking any way to test it I cheekily asked if he would take $50 for the radio ... "Sure", he said and my wallet was instantly $50 lighter.

Now I have a few vintage radios at home, perhaps a few too many depending on who you ask, and I consider them all to be interesting examples in their own right. More or less money, time and research was employed to create these radios and a great variety of circuits and designs was the result.

First impressions told me this was different, I had never owned anything like the Atwater Kent radio before. It was certainly older than my other radios but it was also constructed unlike any other radio I owned. Even under layers of grime, dust and mud dauber's nests this was obviously an article of quality. The finish on the wood cabinet and the metal front panel had seen some heat and were very badly checked in addition to the 90 or so years that had taken its toll. On the lip of the hinged top was a protected area which still showed how the finish looked originally, the dark mahogany and subtle gloss hinting that it had once looked very smart indeed.

The model 20 compact or AK20C

Once I had Internet access again I started to research the model 20 and try and learn something about it. It was at this stage, after some initial confusion, that I noticed that my model 20 was the older and perhaps slightly rarer "Big Box" version. There isn't much between them but some important differences crop up as far as restoration goes, for example:

Most references I found online suggested that the front panel of the model 20 was painted with a crinkle finish however this was only true of the later versions.

In an Atwater Kent advertising booklet, published at the time, they write, "The front of the cabinet is of metal with a deep brown mat surface which brings out the sparkling sheen of the lighter brown Bakelite dials, knobs, etc., and the nickel-plated trimmings."

I'll need to clean my Bakelite parts and possibly wax them to bring up the original "sparkling sheen" of the tuning, aerial tap and filament rheostat knobs.

A suggestion from the Antique Radio Forums that Rust-Oleum Earth Brown paint followed by black KIWI boot polish applied using 0000 steel wool sounds like it would come pretty close to producing the right finish and will probably be the path I choose when I refinish the front panel.

This AK20, from The Backwood Realm, appears
to have the original finish and looks similar to mine.

For the woodwork we're fortunate to find the description below and some more research indicates that nitro-cellulose lacquer was used at the time and is still available now.

"The cabinet of the Model 20 Receiver, pictured above, is of solid mahogany, stained a dark brown, then shellacked, triply lacquered, and rubbed to a dull, glossy, long-wearing finish."

Overall it seems very understated compared to modern electronics, even down to "The name plate, of dull bronze, is both distinctive and unobtrusive."

I hardly need to say, to most folks at least, that Ebay is a wonderful, and terrible, place to shop for antique radio parts. Wonderful because at any one time there are parts available for just about any radio you might have and terrible because you'll be jostling with tens, or hundred, or thousands of other collectors and re-sellers ... many of which have some very deep pockets indeed!

Unused Atwater Kent Radio Log card.

After vowing I would never pay Ebay prices I lasted approximately 3 minutes and then started looking on Ebay for some of the things I knew I was missing.

Before too long I had found an all-important unused "Atwater Kent Radio Log" card and envelope. I intend to scan these items in with a high resolution flat bed scanner and make copies to use and share.

Also I was able to get a set of three tuning knobs since one of the originals on my radio was shattered. Although someone had thoughtfully placed the remains inside the cabinet it was never going to piece back together well enough to look "right"

I had found the Atwater Kent Radio Instruction Book Vol. 2 online and printed out a copy but couldn't resist the temptation to pick up an original as well as another envelope along with some instruction sheets for various models of AK loud speakers.

I already own a modern ARBE-III battery eliminator so this really left only one thing to find ... a loud speaker.

Even the parts you don't see, are expensive.

I should have known that finding "the right loud speaker" for the model 20 would not be a simple task. While it will work with many different speakers including later cone style Atwater Kent units and those manufactured by other companies, the "right" speaker ... the type shown in all the period advertising literature ... is the Atwater Kent type M, L, H or R radio speaker.

All but one of those models allegedly used pot metal in their construction which eventually succumbs to the dreaded "pot metal disease" making it crack and expand. I have dealt with pot metal disease before and have no intention of doing battle with it again ... this left one model, the model M, as the one I was looking for.

Ok, so there was one model M listed on Ebay and it looked to be in good condition as well as "working" according to the seller. In fact the more I looked at it, the better it looked ... it seemed to be in very nearly new condition. After I finished drooling over the photographs I decided that I would limit myself to $100 not including the $50 shipping involved. The shipping was more than average and I hoped this would keep bids low and reduce the amount of interest. This seemed to work for a while ... the bids topped out at around $80 and I thought I might be on a winner, however this was short lived and the bids jumped to over $100 and kept on going. "Ah well", I thought, "such is life". I knew there would be an vintage and antique radio auction coming up in a month and I could probably find something there at a reasonable price.

The Atwater Kent Type M Loud Speaker.

At this point I took a shower, which is something I would recommend to anyone suffering some disappointment ... or a bath. Worst case you end up cleaner if still disappointed which is surely a small improvement.

At the same time my wife, who perpetually despairs of ever buying the right gift for a husband who is notoriously difficult to buy for, noticed my dejection and moved over to my computer which I had foolishly left logged into Ebay (I should know better, really).

A furious round of bidding started between my wife and a number of others who knew little of her determination to win this auction. I won't mention the final amount, I would like to say because, "One doesn't discuss money" but mainly because it still makes me a little woozy to think about.

If you were bidding on that same speaker then I apologize, but you never really stood a chance.

After further research I've learnt a bit more about the internals of the AK20 and uncovered the meaning behind its three tuning dials and various other controls. In order to provide more amplification, not to mention more selectivity, the AK20 uses three largely identical tuned circuits. Each tuned circuit is controlled by a separate knob on the front panel and all three must be "in agreement" before you will hear anything from the loudspeaker. Next comes the detector circuit which converts the amplitude modulated radio frequencies into audio frequencies and finally two further stages of audio amplification.

The other controls on the front panel are the aerial tuning switch which selects different taps on the first set of coils and the filament rheostats. The filament rheostats, in addition to correcting the voltage supplied by the batteries to the vacuum tube filaments, also act as the volume control by lowering the filament voltage which in turn lowers the volume from its maximum to a comfortable listening level.

Next steps will involve re-finishing the front panel and cabinet, checking tubes along with the few capacitors and resistors, then a careful power-up with high impedance headphones ... the AK loud speaker can wait until I am absolutely sure that it is working as intended!

I hope to update the blog as I progress, as well as uploading pictures and more detailed data such as circuit diagrams and service information HERE.

Where to find the $20 Software Defined Radio?

A while back I wrote a blog post about the availability of $20 software defined VHF/UHF radios in the form of re-purposed USB digital television dongles.

Now-days, with the improvements in software and documentation, the hardest part is finding the right dongle. What you order from EBay, and what you receive, can be two different things and only some of the dongles are suitable for use as VHF/UHF software defined radios.

So, I was pleased to see that at least one hobbyist electronics supplier has sought out and supplies a suitable device for SDR at a fair price :

Adafruit has available the USB dongle and "antenna" suitable for experimentation for $22.50, not far from the EBay (direct from China) price.

Click here to go directly to the product page: Software Defined Radio Receiver USB Stick - RTL2832 w/R820T

No, I didn't receive a free evaluation unit and I don't work for Adafruit ... I'm just glad to see these useful devices available from a local company with an increased chance of you "Getting what you paid for."

Adafruit also helpfully stock the adapter cables to convert the less common MCX antenna connector into the much more common BNC connector: MCX Jack to BNC RF Cable Adapter

Desert Farming Experiment Yields First Results

Desert Farming Experiment Yields First Results | Science/AAAS | News

A project to “green” desert areas with an innovative mix of technologies—producing food, biofuel, clean water, energy, and salt—reached a milestone this week in the Gulf state of Qatar. A pilot plant built by the Sahara Forest Project (SFP) produced 75 kilograms of vegetables per square meter in three crops annually, comparable to commercial farms in Europe, while consuming only sunlight and seawater.  The heart of the SFP concept is a specially designed greenhouse. At one end, salt water is trickled over a gridlike curtain so that the prevailing wind blows the resulting cool, moist air over the plants inside. This cooling effect allowed the Qatar facility to grow three crops per year, even in the scorching summer. At the other end of the greenhouse is a network of pipes with cold seawater running through them. Some of the moisture in the air condenses on the pipes and is collected, providing a source of fresh water.

One of the surprising side effects of such a seawater greenhouse, seen during early experiments, is that cool moist air leaking out of it encourages other plants to grow spontaneously outside. The Qatar plant took advantage of that effect to grow crops around the greenhouse, including barley and salad rocket (arugula), as well as useful desert plants. The pilot plant accentuated this exterior cooling with more “evaporative hedges” that reduced air temperatures by up to 10°C. “It was surprising how little encouragement the external crops needed,” says SFP chief Joakim Hauge.

The third key element of the SFP facility is a concentrated solar power plant. This uses mirrors in the shape of a parabolic trough to heat a fluid flowing through a pipe at its focus. The heated fluid then boils water, and the steam drives a turbine to generate power. Hence, the plant has electricity to run its control systems and pumps and can use any excess to desalinate water for irrigating the plants.

The Qatar plant has also experimented with other possibilities such as culturing heat-tolerant algae, growing salt-tolerant grasses for fodder or biofuel, and evaporating the concentrated saline the plant emits to produce salt.

The Qatar plant—which is supported by Qatari fertilizer companies Yara International and Qafco—is just 1 hectare in extent with 600 square meters of growing area in the greenhouse. The fact that this small greenhouse produced such good yields, Hauge says, suggests that a commercial plant—with possibly four crops a year—could do even better. SFP researchers estimate that a facility with 60 hectares of growing area under greenhouses could provide all the cucumbers, tomatoes, peppers, and egglants now imported into Qatar. The results “reveal the potential for enabling restorative growth and value creation in arid land,” Hauge says. "I personally think that it is very important that people promote and invest in these ideas. Protected agriculture (I call it "indoor food production") is an important option for the desert areas, particularly in the Middle East," says Richard Tutwiler, director of the Desert Development Center at the American University in Cairo. "The big question is economic feasibility. How much did it cost to produce 75 kg of cucumbers per square meter?"

SFP is now engaged in studies aimed at building a 20-hectare test facility near Aqaba in Jordan. “This will be a considerable scaling up from the 1 hectare in Qatar,” Hauge says, and big enough to demonstrate commercial operation.

Shock and Awe - The story of electricity.

Amateur radio has a long history, going all the way back to wireless experiments in the late 1800s. However the study of electricity has its roots in the observation of natural phenomena and stretches back much further.

I ran across this excellent three part documentary detailing the story of the discovery of electricity. The presenter is Jim Al-Khalili, currently Professor of Theoretical Physics and Chair in the Public Engagement in Science at the University of Surrey. He not only knows his stuff, he is also an interesting and engaging speaker.

The documentary runs for three hours but is worth your time if you are interested in the story of electricity and the people behind its discovery and history. I hope you find it as enjoyable as I did.

At 522,000,000 miles per watt, Voyager 1 might be the ultimate in QRP.

At 522,000,000 miles per watt, Voyager could be the ultimate in QRP ... if you have the right antenna.

For most HAMs the experience of seeing sub-one watt WSPR signals decoded from across the globe is enough of a thrill. However, the fine folks at the National Radio Astronomy Observatory have taken this a little further and used the Very Long Baseline Array radio telescope to precisely pinpoint the position of the Voyager 1 space probe.

While the layperson might see detecting the glimmer of 22 watts across the vastness of space miraculous, the amateur radio community can see this feat as the natural evolution and refinement of the technology and medium we know and love.

From nrao.edu:

Earlier this year, the National Science Foundation's Very Long Baseline Array telescope turned its gaze to NASA's famed Voyager 1 and captured an image of this iconic spacecraft's faint radio signal. The Green Bank Telescope also detected Voyager's signal, picking it out from the background radio noise in less than one second.

Astronomers using the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) and Green Bank Telescope (GBT) spotted the faint radio glow from NASA's famed Voyager 1 spacecraft -- the most distant man-made object.

According to NASA's Jet Propulsion Laboratory (JPL), the VLBA imaged the signal from Voyager 1's main transmitter after the spacecraft had already passed beyond the edge of the heliosphere, the bubble of charged particles from the Sun that surrounds our Solar System.

Using NASA's Deep Space Network, JPL continually tracks Voyager and calculates its position on the sky, which is known as the ephemeris. Since the VLBA has the highest resolution, or ability to see fine detail, of any full-time astronomical instrument, NRAO astronomers believed they could locate Voyager's ephemeris position with unprecedented precision. This is unrelated to Voyager's distance from the Sun or position relative to the heliosphere.

The initial observations, which were made on February 21, placed Voyager very near, but not precisely at its predicted location. The difference was a few tenths of an arcsecond. An arcsecond is the apparent size of a penny as seen from 2.5 miles (4 kilometers) away. The second observations on June 1 produced similar results.

"It is possible that these observations are at the milliarcsecond [one-thousandth of an arcsecond] level, or better," said NRAO scientist Walter Brisken, who led the observations with the VLBA. At 11.5 billion miles -- Voyager's approximate distance at the time of the initial observations -- one milliarcsecond would be roughly 50 miles across.

Voyager's main transmitter shines at a feeble 22 watts, which is comparable to a car-mounted police radio or -- in visible light -- a refrigerator light bulb. Though incredibly weak by the standards of modern wireless communications, Voyager's signal is astoundingly bright when compared to most natural objects studied by radio telescopes.

"The ability to pinpoint the location of Voyager and other spacecraft is critical as we explore the inner Solar System and beyond," said Brisken. "The NRAO's VLBA has the capability to do this vital task with unprecedented precision."

Voyager 1, which was launched in 1977, is now headed away from the Sun at a speed of about 38,000 miles per hour.

In a remarkably sensitive complementary observation, the NRAO's Green Bank Telescope (GBT), which is the world's largest fully steerable radio telescope, easily detected Voyager's signal, picking it out from the background radio noise in less than one second.

"Voyager is the first man-made object to penetrate the interstellar medium, and we really want to be able to receive the data from this new frontier," said NRAO scientist Toney Minter, who oversaw the Green Bank observations. "This information will provide many clues about how the interstellar medium behaves and how the Sun interacts with it."

"NRAO's instruments have the capability to provide the most accurate position information of distant spacecraft like Voyager," said NRAO Director Tony Beasley. "The remarkable sensitivity of GBT and VLBA's sharp vision are essential for discovery but also have unique capabilities that have enabled us to make this contact with one of humanity's most ambitious missions of exploration."

The VLBA is a system of radio antennas located across the United States from Hawaii to St. Croix. The antennas work together as a single telescope nearly 5,000 miles across, giving the VLBA its ability to see fine details. Only seven of the VLBA's full complement of 10 antennas were used to make these observations.

The 100-meter GBT is located in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone, which protect the incredibly sensitive telescope from unwanted radio interference. The GBT observations were made by NRAO scientists Toney Minter and Frank Ghigo, and Green Bank Director Karen O'Neil.

From Backblocks To High Seas

I came across this great piece of history via the Google+ page of Cristian YO8TNB and had to share it here for others to enjoy. I have a soft spot for New Zealand, being so close to my country of birth, and I particularly noticed the carefully cultured accent of the announcer. On a more serious note, this video is an invaluable record of the wired and wireless technology used in 1939 and the procedures for transmitting a message from land to sea.

KARS Presentation - Ham Radio Resources on the Internet

At the Katy Amateur Radio Society business meeting I presented a brief rundown of a Internet resources that might interest the Radio Amateur. Here is that presentation in Google Docs format. 

Click here to access the presentation in Google Docs Format

Ham Radio Resources on the Internet