[MrFixr55]

Hi Peter,

Wishing and praying for peace throughout the world and in your region. Passover and Easter Blessings to you and yours!

Regarding RCA's use of Class B Amps, apparently, RCA discovered (or someone else discovered and RCA took credit for it like they usually do) tubes that could put out a motherload of power in "Class B". RCA used to claim that any output stage with a total harmonic distortion of less than 5% was "undistorted", so Class B was somewhat popular with them. For example , the "53" and 6N7 could put out 10 watts. The 49 and 19 tubes with 2V filaments, used in "farm" sets could put out 2W. 2 46s could put out a whopping 20W as opposed to 2 47 pentodes in class A push pull which could put out only 3-5W. And yes, they do NOT sound as nice as a Class A or Class AB1 Push Pull amp. RCA won't admit it but the 42 (and I think the 41) were Sylvania inventions, and Philco, a major car radio manufacturer, jumped on that bandwagon quickly. RCA was still into 2.5V tubes, and their version of the 42 was the 2A5.

[RadioSvit]

MrFixr55. I completely agree with you

[morzh]

>>
(or someone else discovered and RCA took credit for it like they usually do)

A friend of mine, he is in his late 80s now, started his career in RCA, in TV division, still under Sarnoff watch.
He had over 100 patents to his name while in there.
One of his patents (they started microchips back then, and he was working on them) was current mirror in AC mode (prior to that it was thought to function only in DC). According to him, RCA made in excess of tens of millions of dollars in royalties alone.
He was given a $200 check.


And their raider-style dealing with Fessenden is a well-known story.
Which does not make them any less of a great company. The same friend admits it was a good place to work.

[radiorich]

Hello Guys,
that is intresting about Class B amps !

Sincerely Richard

[RadioSvit]

And their raider-style dealing with Fessenden is a well-known story.

Michael, I think you were mistaken - they fought with Edwin Armstrong for many years. Or with Fessenden too? I didn't know this...

[morzh]

Well....read about them and their assault on Fessenden's house.

[MrFixr55]

I recently bought the "Bible" on the subject, Eric Wenaas' "Radiola- The Golden Age of RCA". I will have to reread it to see what mention of Fessenden. According to Wikipedia, he was a rather prolific inventor, but like de Forest, not a businessman (although not as involved in as many nebulous business dealings as de Forest was. I believe Fessenden had a lot to do with heterodyning to produce a "tone" in the reception of Morse code. However, the technique did not come to common practice until the invention of the vacuum tube. He was an advocate of "alternators" as sources of radio waves as opposed to the spark gap transmitter. Alexanderson ran with the idea to produce the famous GE Alexanderson Alternator. Some of Fessenden's ideas and patents included the rotary spark gap transmitter, electrolytic detector, CW (Continuous Wave) and AM (Amplitude Modulation), and techniques that were developed into RADAR and SONAR. Fessenden had associations with Edison, GE and Westinghouse. He may
be somewhat of an unsung hero; he should be as famous has Hertz, Armstrong and Marconi.

I remember reading in a 5th or 6th grade reader at school in 1965 or 1966 about the first transmission of voice and music on Christmas Eve, 1906, by Fessenden. (The reader was likely published several years earlier, as the cars illustrated in the reader were late 1940s vintage.) By then I was really interested in electronics. There are now questions as to if anyone actually heard the transmission, which consisted of several scripture readings and recordings, including Adolphe Adams' "O Holy Night". Several of Fessenden's patents were held by a failed company he helped found, NESCO (the National Electric Signaling Company). These patents were eventually transferred to Westinghouse, who bought the company, then to RCA. By then, Fessenden was fired from NESCO.

[RadioSvit]

New video again. "To the 100th anniversary of the beginning of radio broadcasting. Part 2. The invention of the superheterodyne"
There are subtitles. Turn on and watch

[Video: https://www.youtube.com/watch?v=6bsrRBvmhHY&t=41s]

[RadioSvit]

My new video...

To the 100th anniversary of the beginning of radio broadcasting. Part 3. Radio saves lives .

Ukrainian subtitles with automatic translation into other languages. Turn on and watch - an interesting viewing.

[Video: https://www.youtube.com/watch?v=I0bOIXtTNLQ&t=11s]

[RadioSvit]

I made a video about another device from my collection - a rather rare Farnsworth GK-669 radiogram.
Subtitle text from automatic English translation ...

Today I will talk about my favorite 1949 Farnsworth Gk-669 console radio gramophone.
At first glance, there is nothing special either in the design or in the technical characteristics - an ordinary budget 6-tube radio console of the late 40s. The peak of the popularity of these wonderful devices has already passed, the market was saturated with them even before the Second World War, and radio equipment manufacturers in the USA one by one began to stop their production or simply go bankrupt and close. This bitter fate did not pass by Farnsworth either - the 49th year was the penultimate year and the next year the firm ceased to exist.
From the very first moment after getting acquainted with this device, I had two compelling reasons to buy it - it is the unique sound quality for a relatively simple device and ... its pedigree. The company belonged to the brilliant inventor and owner of many patents, Philo Farnsworth. He was a very gifted scientist and inventor, at the beginning of his career, television fell into his field of interest - in 1927, he created the first electron beam tube, the first experimental television set, and received a US patent for them. In the 1930s, he created commercial television systems for Philco, but due to a conflict with the management, he left the company and created an enterprise in Fort Wayne, Indiana for the manufacture of radios and televisions, but the war began and he had to manufacture military products and sell his patents to the RCA Corporation. After the war, his company produced high-quality high-fidelity radio consoles, but due to a decline in demand in the early 1950s, it was forced to close. Nevertheless, being a genius, he worked for the US Military Industrial Complex, developed missile control units, later engaged in nuclear physics and even created a portable nuclear reactor. (!)
Let's return to our topic... This model of radio gramophone was on the lowest step of the company's product line. Yes, the design is not impressive, but it is soft, not flashy and quite stylish - at the end of the 40s, such a simplified design with flat panels was in trend. Five bands, coverage from 520 kHz to 22 thousand. Since there is no radio frequency input amplifier, the sensitivity is not impressive. There is also a rather weak amplifier of only 5 watts. However, we do not forget that this is a budget. But what pleasantly surprised this device was the high sound quality and high sound pressure thanks to the 30-centimeter speaker on a permanent magnet.
Excellent microdynamics revives even old pre-war gramophone records, and all friends and acquaintances who have managed to listen to it say that the sound is lively and not at all similar to modern ones. What can I say - if a simple 6-tube budget budget player sounds so nice, then one can only imagine how the 22-tube flagship of this company would sound if I had it...)
The automatic changer of gramophone records deserves special attention - you load 10 pieces and you can listen to music for half an hour without getting up from the chair opposite... In general, I am very impressed by the commitment of Americans to automatic changers, I see this even on very simple budget devices. At first, a 78-rpm self-made Farnsworth automatic record player with a metal needle and diamond dusting was installed here, but a year earlier, in 1948, the 33-rpm Long Play standard with long-playing records appeared and the native record player instantly became obsolete. It is obvious that for this reason the previous owner replaced it with a more modern Webster Chicago changer model 355 of 55 with a piezo head and a corundum needle.
You can talk a lot more about the features of the design or characteristics of this radio gramophone, but it is unlikely that it will be very interesting to non-specialists, so I suggest you watch a short video, assess the degree of exclusivity of this device yourself and just listen to the music of the 40s...

[Video: https://www.youtube.com/watch?v=2PGh6RjDmh0]

[RadioSvit]

From the archive video of 2021.
RCA C8-20 radio console. A journey through the modern ether. What's left and what can still be caught on the radio as of December 2021.

[Video: https://www.youtube.com/watch?v=9vMsr5VktZs&t=3s]

[RadioSvit]

On-duty Friday video ... I wish everyone a good mood from watching 

Old Philco 37-640x tube radio console. USA 1936//Old Philco 37-640x tube radio console. USA 1936

For a long time I was going to make a video about one very interesting device - the American radio console Philco 37.640 of 1936.
What is so interesting about this device? I will try to take my time to tell about all its advantages and possibly some disadvantages.

Let's start with the design ... Like most models of the Filko company, its design is quite simple, nothing special stands out against the background of competitors, but at the same time it is specific and always recognizable - radio receivers of this company are quite difficult to confuse with radio receivers of other manufacturers.

The quality of the cases was very high, for their manufacture, high-quality veneers of several types were used, mainly American walnut, and decorative overlays made of solid expensive wood types were used quite often. Sometimes even decorative hand-carved figurines. But since this is almost a budget model, the design was done without exclusivity.

  In the season of the thirty-seventh model year, which began in the summer of the thirty-sixth year, Philco's hallmark was the round frame of the scale, which replaced the oval-shaped scale of the 35/36 models.

But the most interesting thing is hidden in the middle of the radio, in the chassis, and by our standards it is definitely not for a budget radio. What exactly ? Let's see... In my many years of antique radio fun, I have yet to come across any other seven-tube radio receiver with a powerful three-tube two-stroke audio frequency amplifier and a high-frequency amplifier with a balanced input, and also with a fine tuning indicator.

  How is this even possible with only seven radio lamps??? For such a cascade configuration, there should be at least nine of them!
Everything is ingeniously simple - by applying a clever scheme of a combined phase inverter on one of the two radio tubes of the output stage, it was possible to save one radio tube and make a sound amplifier with only three radio tubes. Compared to a standard two-stroke, this type of amplifier has slightly worse characteristics and lower power, but 6...7 watts is always better than 4.
  And let's not forget that this is still a budget. For the same reason, only a ten-inch loudspeaker with electric magnetization is installed here instead of a twelve-inch one, which slightly reduced the sound quality.

The second trick made it possible to save on one more radio lamp, we are talking about the so-called shade meter, a "shadow" indicator that replaced the "green eye" radio lamp of the optical setting indicator.

Well, such a masterpiece of circuitry as a high-frequency amplifier with a symmetrical balanced input puts this radio console two steps above its competitors. Let me explain - this technical solution allows you to dramatically reduce the level of interference in the radio airwaves and thereby significantly improve the quality of radio reception. Let me remind you that radio interference on the air is the biggest disadvantage of all radio receivers when receiving medium and long waves.

And here I sprinkle ashes on my head - for 8 years of owning this unique device, I have never built a suitable balanced antenna for it with symmetrical reduction... But when I do, I will definitely make a separate video, because it should be worth it...
So, let's get acquainted with this device on video and evaluate its reception on short waves from a conventional antenna.

[Video: https://www.youtube.com/watch?v=lCRqx9uDw9s&t=153s]

[Ron Ramirez]

Officially, it's a 1937 model. Don't be fooled by Radiomuseeeeeum's habit of ignoring manufacturers' model years.

Yes, they were introduced in May-June 1936. But they were called 1937 models.

Here in the USA, a new radio line began in May-June of the preceding calendar year back in the years of the "golden age of radio". Much like a new model year of automobiles used to be introduced here in September of the previous calendar year.

[Arran]

Peter;
  Shadow meters, or shadowgraphs, pre dated magic eye tubes, I believe that Philco introduced them in 1932-33, though they were not the only manufacturer that used them, though they may have been the last. Philco never used Magic Eyes on any of their domestic U.S, or Canadian models. Magic Eye tubes debut in the 1936 RCA models and were a bit of a craze for a time, and it was an easy way to add an extra tube to a set without really changing the circuitry. Manufacturers would add a magic eye to a five tube set, and market it as a six tube, or add it to a six tube set and advertise it as a seven tube model, all the way up the line. Another scheme was to use a separate 1st audio tube (triode) and second detector tube (double diode) which really add nothing to the performance of the radio, especially if only one diode is used, a waste of electricity.
Regards
Arran

[radiorich]

Hello Peter,
Nice Video !

Sincerely Richard