More on Prewar RCA Television
COMPILED BY RAY BINTLIFF FROM INFORMATION FURNISHED BY ANDY EMMERSON, DARRL HOCK, STEVE McVOY, OSBORNE PRICE,
CRAIG ROBERTS, AND LUDWELL SIBLEY
In the January 2002 issue of A.R.C., Ray Bintliff's article "The RCA-Soviet Union TV Connection" described the similarity between two RCA prewar TV sets, one of which was intended for the Russian market. As is often the case, A.R.C. readers responded and provided additional information, which we are pleased to share with our readers. (Editor)
My article in the January 2002 issue of A.R.C. was based on some photographs acquired at an auction. The article closed with a request for additional information. I was not disappointed -- it seems we hit the mother lode. Most gratifying was James O'Neal's excellent article RCA's Russian Television Connection that appeared in the August 2002 issue of A.R.C.
Early Field Tests
About 100 Model RR-359 TV sets were produced for use in field testing. The initial models were made with 9-inch picture tubes, but many were later modified to use 12-inch tubes. The modified sets were designated as RR-359B. An example of this version is shown in Figure 1. There are two known surviving 9-inch sets. It is estimated that eleven or twelve of the 12-inch sets exist.
RCA customarily placed new products in various field locations for performance testing under "real world" conditions. For example, in the 1950s, preproduction color TV sets were placed in the homes of RCA and NBC executives. Field testing of the RR-359s was not only a test of the hardware, but also of the reliability of the reception of VHF signals.
Figure 1. The RCA Model RR-359 TV was used in the 1936 field tests. The set shown is a RR-359B, a later version that used a 12-inch picture tube.
In the 1930s, VHF was the realm of Hams and experimenters, and much remained to be learned about signal propagation at VHF. It is interesting to note that some RCA literature from that period referred to the TV frequencies as UHF. Another purpose was to test the set's practicality as a home instrument -- could it be operated by a nontechnical viewer?
Description of the RR-359
Although the RR-359 field test receiver was the precursor to the prewar TRK series of commercial sets, it was primitive by comparison. A 33-tube set, it used a 9-inch kinescope (RCA preferred the term "kinescope" to describe a CRT used in a TV set). Tuning was continuous from 42 to 84 mHz. The tube complement was a mix of old and new. Old standby tube types such as the 1V, 6D6, 27 and 42 were used as the horizontal damper, IF amplifier, local oscillator and horizontal output respectively.
At the other extreme were the developmental tubes used in the critical stages of video IF and mixer. Separate IF stages were used for video and sound -- a design that continued for several years until the introduction of intercarrier sound.
Both the field test sets and the TRK series lacked an RF stage. As a result, the set's antenna radiated the local oscillator's signal. It was not until the early postwar period, as the ownership of TV sets grew, that interference from the local oscillator in the prewar sets became a noticeable problem. (See sidebar.)
An updating program was initiated shortly after the sets were placed the field. Probably the most significant change, at least in the eyes of the viewers, was the use of 12-inch black and white kinescopes, instead of the 9-inch yellow/green displays used in the first models of the RR-359. The commercial version of this new black and white tube was dubbed the 12AP4 and used in the TRK-12 models.
The Model RR-359 was preceded by a 1932 all-electronic field test set. A 7-inch "mirror in the lid" style set, it ran at only 120 lines and 24 frames and produced a low resolution picture. Additional field tests were conducted in 1933 and 1934 with improvements in scanning rates and resolution. The 1933 tests were conducted using 240 lines and 24 frames, while the 1934 tests used 343 lines and 30 frames with interlaced scanning.
A Look Back
A number of sources provide additional information on the RCA-Russian TV connection. For example, an article in the July 1944 issue of Radio Craft states: "Prior to the Nazi invasion, the Soviets were using RCA apparatus in their Moscow television outlet. Native equipment was being rapidly developed after three models. Experimentation had reached a point where a gigantic sight-and-sound studio was blueprinted for inclusion in the scheduled building of the Palace of the Soviets. The war halted all that. Defeat of the Axis will see a resurgence of activity, with emphasis on large-screen, community-type television. Equipment will probably be imported in the beginning with the view of creating a formidable Russian electronic structure."
From Adventure in Vision by John Swift (1950), we learn the following: "The new Moscow Television Centre began re-equipping with an electronic system in 1937, employing largely American apparatus bought from RCA. Leningrad and Kiev followed suit. Test programs began in 1938, but audiences still had to go to factory canteens, communal centres and trade union or Red Army clubs to watch them. Few personal sets were available."
Practical TV was the result of years of research and development starting with what now seems ancient -- the mechanical systems. Anxious as it might have been to market television sets, RCA recognized the risks associated with the premature introduction of this new technology. Field testing played a significant role in the realization of a practical television system.
(Ray Bintliff, 2 Powder Horn Ln., Acton, MA 01720)
Ray Bintliff, a frequent contributor to A.R.C., holds an Amateur Extra Class license. A retired engineer, he enjoys repairing and restoring pre-1945 radios and test equipment. In addition to Amateur radio, his interests include electronic equipment and audio reproduction.
By Ray Bintliff
As described in the accompanying article, the RCA TRK series of prewar TV sets lacked an RF stage. This omission allowed the TV set's local oscillator signal to be radiated by the set's antenna. As a result, TV sets in close proximity could interfere with each other. I still remember one such experience.
This is old stuff. It happened in 1946. But since this is an antique radio magazine, it seems appropriate to tell about it.
We had a TRK-12 owner on Long Island who had become a frequent caller. He said his TV set blanked out at times. We dispatched technicians and antenna crews again and again, but the problem went unsolved. Then we got a clue from the owner. He finally got around to mentioning that the problem only happened at night. So obviously, an evening service call was needed.
The night shift was not in our regular game plan, but we had to make this guy happy. As the great slayer of dragons, I was called upon to go forth and do good. So I saddled up and arrived at the owner's home at about 7 p.m. He was happy to see me and placed a gin and tonic in my hand. Then we sat and watched TV and had another round. I thought, "This isn't a bad way to make a living." Then, the TV screen went blank, well, not really blank. It was mostly black with a beat pattern that was barely visible.
Clearly, a neighbor had turned on a set and the oscillator's signal was swamping our customer's set. When I explained the problem, the guy assured me that he was the only TV owner in the area. You must remember that in 1946, owning a TV set, prewar or otherwise, was something of a status symbol.
I suggested that we take a walk around the neighborhood. We did, and I spotted a TV antenna on a house just two blocks away. Oh my! Our guy was not king of the hill. There was another TV owner in the neighborhood.
I knocked on Number 2's door and explained our mission and asked him to change the offending TV, another TRK-12, to another channel. We returned to our guy's house, and the set looked good. OK, now what? Do I tell him that RCA should have included an RF stage? What I told him was that he and his neighbor would have to coordinate their channel selection. After all he was in a weak signal area and the 6J5 in his neighbor's TRK was a great little oscillator. Oh yes, we had another gin and tonic.