Tag Archives: History

A Blast from the Past …

I obtained my FCC Novice license in 1957 at age 13. At that time, I didn’t yet have a station, so I set out to remedy that situation. I had been using a Heathkit AR-3 receiver (4 tube superhet, $29.95 in kit form, cabinet $4.95 extra) I built prior to obtaining my license; while OK for SWLing,  it wasn’t well suited to amateur radio work. My first priority was building a homebrew transmitter while looking for a more suitable but affordable receiver. While I was building the transmitter, my father borrowed a WWII German military receiver from a colleague at work for me to use temporarily. I didn’t know it at the time, but this receiver was a quite sophisticated design. I used this receiver for several months (including for my first ever QSO), but didn’t pay much attention to the details as most of the labeling was in a language I didn’t understand, and I had no manual, other documentation, or knowledgeable guidance.

I recently decided to see if I could more precisely identify this receiver based on my recall of a few unique features of the design.  One very clear recollection is that the frequency display was projected onto a ground glass screen on the front panel.  This turned out to be the definitive clue in identifying this receiver. Another recollection is the strange-looking (to me, at least) vacuum tubes, the bases of some of which could be seen by opening two flip-up covers on the front panel. Using these clues, it was easy, with some internet research,  to zero in on the make and model of the receiver. It was a Tekefunken E52 series manufactured in several variations mainly for the German Luftwaffe between about 1942 and 1945. At the time, I had no understanding of the advanced nature of this design; it was way ahead of its time, and only about 2500 were built. Below are some photos, snippets, and links from the websites I visited. While likely of limited interest to newer hams, in these days of pandemics, lockdowns, and self-isolating, perhaps an interesting diversion. Much more information on the web for those so inclined.

K8EZB Past
Heathkit AR-3
K8EZB Past
Telefunken E52a-1
Telefunken RV12P2000 Vacuum Tube

Telefunken E52 (Koln)

“This is one of the most studied, written about, and discussed receivers in the world”

History:
Empfänger 52 was specified by the Reichsluftfahrtministerium (RLM) in 1939 as one in a series of five similar receivers covering the entire frequency spectrum from LF to UHF, intended for use in the Luftwaffe ground stations, but also for other services and authorities. A request for quotation went out to a few German electronics manufacturers and Telefunken developed and built a prototype of the short wave receiver Köln in the beginning of 1941. Telefunken was chosen to manufacture the series of receivers according to their specification ”Luftboden-Empf.-Programm 2 – 7500 m für die Bodenausrüstung der Deutschen Luftwaffe”, Telefunken Berlin-Zehlendorf  5.5.1941.

Out of four specified receivers E51 Leipzig (LF), E52 Köln (HF), E53 Ulm (VHF), and E54 Kulm (UHF) only Köln was built in large series. In total around 2500 receivers were built from July 1942 to March 1945. The E52 was made in 10 models, of which the E52a-1 (simplified with automatic tuning) and E52b-2 (simplified with manual tuning and unified scale) were the most common. Of all the E52s built there are probably 300 – 500 left, of these perhaps 50 in their original state.

The receiver is modularised, the modules are mounted in a molded aluminum chassis and all connections between the modules are through connectors in a backplane! Both the construction and the performance were far ahead of its time. Only one type of valve, the RV12P2000, was used in the receiver except for the power rectifiers. The intention was that all modules and valves should be interchangeable in the field without the need for realignment. The first test series of around 20 receivers were made in Sachsenwerk in Radeberg from July 1942 of the simplified type E52a-1 and possibly also the type E52b-1. The manufacture was not up to speed until the beginning of 1943. The assembly and alignment were made in Sachsenwerk Niedersedlitz while the modules were made in several different electronics industries.

Receiver data:
The receiver is an advanced single superheterodyne with two RF stages, a mixer/local oscillator, three IF stages, a detector/BFO/AF amplifier, and an output stage for headphones. In total there are 6 tuned circuits in the RF/mixer/oscillator part and the receiver has very high sensitivity and selectivity. The IF stages have a 6-circuit filter plus 4 tunable circuits in a variable crystal filter, the bandwidth is variable from +/- 5 kHz down to +/- 200 Hz @-3dB with very steep slopes, damping 100 times at +/- 10 kHz in wide. The tuning has a coarse scale and a fine-scale projected from a micro photo disc with very high resolution and accuracy. The oscillator has very accurate temperature compensation and thus high stability. Frequency coverage is 1.5 to 25 Mhz in five bands, the sensitivity for AM 3 – 5 uV, CW wide 1.0 uV, and CW narrow 0.3 uV for 5 V output. Mirror frequency damping is at least 50000 and the IF damping is better than 100000 at 1.5 MHz. The stability is better than 30x 10E-6/degree C, which is 30 Hz/MHz/degree C for a freerunning oscillator! Even today this is competitive against many modern receivers comparing sensitivity, selectivity, and stability.

Link: https://kriegsfunker.com/radios/E52_b2.html

Rick, K8EZB

A Piece Of Ham Radio History – Do You Know What This Is?

Every now and again one comes across a piece of Ham Radio History. Anita and I had this experience recently during our vacation in Florida. For example, we can across an artifact that we had heard about from Charle, W1CBD but had never actually seen during a recent visit to Florida.

Pretty Basic HT Transceiver
Pretty Basic HT Transceiver

This is a Motorola  MX-340.  This radio was a 5w UHF (or sometimes VHF) FM rig that was popular for commercial applications in the 1970s. You can learn more about the rig here.

A Very Special HT Transceiver

So I bet you are wondering “What makes this old HT so special? Why is it a piece of Ham Radio History?”. Well, here’s a hint – it flew aboard this:

Space Shuttle Atlantis
Space Shuttle Atlantis On Display At The Kennedy Space Center, Fla.

Yup, the little HT flew aboard the Space Shuttle.  Here’s more about our little HTs role via an excerpt  from Wikipedia :

The Shuttle Amateur Radio Experiment (SAREX), later called the Space Amateur Radio Experiment, was a program that promoted and supported the use of amateur (“Ham”) Radio by astronauts in low earth orbit aboard the United States Space Shuttle to communicate with other amateur radio stations around the world. It was superseded by the Amateur Radio on the International Space Station (ARISS) program. SAREX was sponsored by NASAAMSAT (The Radio Amateur Satellite Corporation), and the ARRL (American Radio Relay League).

STEM Learning Through Space and Ham Radio

Ham Radio History - SAREX
Ham Radio Abord The Space Shuttle

Ham Radio has been a STEM learning tool for a very long time. An early example of this was the Shuttle Amateur Radio Experiment  (SAREX) program. SAREX was a partnership between NASA, ARISS, and the ARRL. Its success in bringing Ham Radio to schools and other educational venues led, in part, to the creation of ARISS.

How All Of This Effects NARS

ARISS Crew Contact Transcript
HMS Students Talking to the ISS

And ARISS, of course, has provided NARS the opportunity to be part of bringing contacts with astronauts aboard the International Space Station (ISS) to schools here in New Hampshire, around the United States, and around the world.

There are many such examples of Ham Radio History that resulted in great things for many people. Perhaps you know of one? If so, please consider taking writing about it here on our Blog.

Fred, AB1OC

Reginald Fessenden Makes Christmas History

For our October 2017 meeting, we had Professor Donna Halper speak about the history of amateur radio and its heroes. Having heard her speak at Boxboro 2016, I knew our members were in for a treat. So in keeping with this theme, I searched for some interesting nugget, some salient morsel about the history of amateur radio that was somehow linked to Christmas time. I struck gold when I came across Reginald Fessenden.

A brief segue into the life of Reginald Fessenden

Reginald Fessenden, looking dapper and scholarly.

Reginald Fessenden was born in 1866 in Quebec and showed an aptitude and high interest in mathematics / engineering from a young age. Though he did not have a degree, he desired to work in the field of electricity, and so he went to the Mecca of electrical work in the U.S., namely NYC in 1886 to work with Thomas Edison. He personally wrote Edison saying “Do not know anything about electricity, but can learn pretty quick,” to which Edison replied “Have enough men now who do not know about electricity.” Luck had different plans, however, and he ended up obtaining a job with Edison and rose through his company quickly to even work directly with Edison at his new laboratory in NJ. He was laid off in 1890, however, due to financial problems Edison encountered, and so Fessenden searched for additional opportunities.

In 1900, Fessenden went to work for the U.S. Weather Bureau with the goal of “proving the practicality of using a network of coastal radio stations to transmit weather information, thereby avoiding the expense of the existing telegraph lines.”  The Bureau would have access to any devices he created but he could retain the rights to ownership. He quickly advanced receiver design with one notable achievement being the development of the heterodyne principle among other advancements such as the invention of a barretter detector and electrolytic detector.

After his time with the weather bureau was up, Fessenden was able to secure funding for his research that led to the design and implementation of a rotary-spark transmitter (continuous wave phenomena was not thought to produce wireless communications and it was in fact Fessenden himself who championed the theory and practice of CW signals as understood by Hertz) and the world’s first trans-atlantic transmission — that of Morse code. Unfortunately, at the time, the destruction of one of the radio towers led to the end of the project.

Fessenden soon became obsessed with audio radio transmissions as opposed to his colleagues of the day (Marconi included) that advocated Morse code transmissions. He in fact applied for and was awarded a patent in 1901 for essentially inventing a CW transmitter! The man was unstoppable. Soon after he learned how to modulate speech on his CW waves to create Amplitude Modulated (AM) radio waves.

Upon reading more about Fessenden, his career seems to have comprised breakthrough after breakthrough in the field of radio engineering. I could go on and on regarding all his accomplishments, but if I did, I still would have not arrived at the point about what any of this has to do with the holidays.

The connection to Christmas Eve

Until the early 1930’s, it was widely believed that a gentlemen by the name of Lee de Forest was the first person to transmit music and speech by radio in February 1907. Fessenden, however, challenged this notion when it was advertised by other scholars that Fessenden had in fact accomplished the pioneering benchmark by broadcasting on Christmas Eve 1906. Specifically, he claimed that he played a phonograph of Handel’s Ombra mai fu (Largo) and then he himself played a violin rendition of O Holy Night and also sang Adore and be Still by Gounod. Furthermore, he also stated he broadcasted on December 31st of the same year and that his transmissions were heard as far as Norfolk, VA on Christmas Eve and  the West Indies for his New Year’s Eve transmission.

Now the interesting bits are that in 2006 (the centennial of the broadcast) renewed interest was sparked into Fessenden’s groundbreaking feat. But, surprisingly, questions were raised. Some of these were that there seemed to not exist any independent corroborations that the transmissions were heard. It is widely believed Fessenden had the technical means to make the transmissions, in the first place, but that it was uber QRP and so may not have been heard by many. Additionally, it was uncovered, that in 1956 more detective work went into verifying the Dec 24th transmissions but again, it failed to uncover any evidence.

If one continues to read about this intriguing individual, you will even learn that Donna Halper (the same one I mentioned at the beginning of this post) and Christoper Sterling  argued “that debating the existence of the holiday broadcasts was ignoring the fact that, in their opinion, the December 21 demonstration, which included the playing of a phonograph record, in itself qualified to be considered an entertainment broadcast”. (I think instead of Dec 21, they meant Dec 24) And other scholars argued there is no reason to discount or doubt Fessenden’s account since it was not challenged immediately following an article, in 1932, originally detailing Fessenden’s story.

So, where do things lie now? Well, the IEEE recognizes this event to be a IEEE Milestone. And, from the little investigative work I did for this post, it seems his account is widely believed. But, even if it weren’t true, it’s pretty dang cool that Fessenden gets to share his achievement with St. Nick’s biggest work day of the year.

Hope you all enjoyed the history lesson and Happy Holidays everyone!

Brian, AB1ZO

 

 

 

Radio Amateurs Developing Skills Worldwide