(003W-2)

Excerpt from “50 Year History of Tokyo Electric Company”

Part II: Transmitting Tubes (p.p.:437-445)- 8 Pages

4) Progress of Transmitting Tubes

a. Production of transmitting tubes
As described earlier, it was 1919 when we completed first Japanese triode transmitting
tube. At that time, we manufactured Types A, B & C Pliotron. Those were 30W input class,and their anode was Tungsten wire wrapped around a glass frame. They were supplied toJapanese Post Office, and used in short distance wireless transmitter.
The tube manufacturing technique at that time was still very poor, and experiencegained by light bulb and X-Ray tube production was utilized partially. Therefore
tremendous effort has spent for their production.
At around 1921, demand for transmitting tubes for domestic users including military
offices arose, and KM-157, UN-151 (also called as 12V lamp), KM-155, KM-156 etc. weremanufactured in prototype base, and also started trial production on Type D Pliotron bynavy’s order.
For such an effort spent by our company in a difficult time, we received award from army
ministry, and subsidy from a government office.
In about 1923 we succeeded production of KM-154 (250W) and KV-204 (1kW) tubes. We
also completed MT-6 (predecessor of UM-156) by navy’s order for 1.5kW class. This tube
exhibited excellent performance at a navy’s test yard. Those tubes were the first large tubes
manufactured in Japan without question.
Those success was owing to progress in our research and production facility, but the huge
earthquake struck about this time destroyed everything in one morning, and gave us hugecasualty. But as navy and other governmental help accelerated rebuilding, and in next year,
1924, we saw tremendous recovery as producing 50-60 pieces of 150W to 1.5kW input classtube daily. The trial production of 3kW input class tube took place, and also exhaust processusing liquefied air started about that time.

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b. Adopting Trend for Shortwave; Tubes and Machinery
Start of radio broadcast in Tokyo, Osaka and Nagoya in 1925 accelerated our tube
production, and transmitting tubes of Marconi type, U.S. types, etc. were announced:
UM-154, UM-155, UM-156, UV-203, UV-204, KV-206, KV-208, etc. were examples.
Research on water-cooled tubes have also started.
As a trend of wireless field at that time was toward short wave, we started research
immediately, and in 1926, introduced SN-204, SN-206, SN-208, etc. which show good
performance in short wave area. They were forerunner of making short wave reach actual
use, and we have received an award from the government for it. It has accelerated our effort
further.
In 1926 we have completed UN-208 having 5kW of input power, and also made prototype
of UV-203A and UV-204A with Thoriated Tungsten filament completed.
After that, utilization of vacuum tubes arose year by year, and its demand hascontinuously increased. Therefore we expanded our production and research facility several
times, but still never enough to catch up the demand.
In 1927 the first water cooled tube, UV-207 with 30kW of input power was born. This
gave a shock to our tube industry, and made our company’s position in the industry evenbetter.
In 1928-29, popularization of radio receiver promoted production of A.C. operated
receiving tubes, and our company has led industry for success of today’s broadcast business,and timing of start producing transmitting machinery came about that time.
In 1929 we completed UX-860 and UV-861 (both tetrodes), and used them in 40kW shortwave transmitter developed with Kokusai Musen Company. This 40kW transmitter wascompeted in 1930, and was the first one in Japan for all domestic production of high power
short wave transmitter, and all tubes used in the set were made by our company.
In particular, mercury vapor rectifier HV-969 used in the set was superior in much lower
voltage drop compared with ordinary vacuum rectifier, consuming small filament power,and exhibits excellent performance compared with U.S. product.
In 1930 HX-966, HV-972, etc. were manufactured, and weaken area of use of vacuum
rectifier further, and then HV-951, HV-966A, HV-972A, etc. were marketed, and succeededtaking over the vacuum rectifier’s position completely.
In the other hand, research of thyratron which added a grid in the mercury rectifier has
conducted in parallel. This type of tube is much suited for controlling electric power, buthave drawback as low usable frequency, and therefore range of its use had to be limited.
Thus our production technology was advancing day by day, parallel to western world’s
tube industry in producing high power, high performance tubes simultaneously, and made2

it unnecessary for importing foreign products anymore. Therefore all governmental offices
started specifying purchase of our products, and foreign products were totally eliminatedfrom Japanese marketplace. This phenomenon is really welcoming situation in terms of ournational interest, not only joy of our company.
The total number of transmitting tubes recently marketed exceeds 50 types, and picking
up representative products from them as follows:
Triodes: SN-157 (3kW input), SN-161 (5kW input), SN-205C (1.5kW input), etc. andTetrodes: UV-811 (5kW input), UV-812 (500W input), UV-814 (125W input), etc.
And the one which calls for special interest is a water cooled triode tube with 200kW ofinput, UV-169. It has completed in 1933, and made an epoch in the transmitting tube
industry at that time.
In the other hand, research and production of magnetron tube was taking place. Theinterest in the ultra-high frequency was accelerated since realization of short wave
communication. We started research on Dynatron, Barkhausen-Kurz tube, Magnetron, etc.
and in 1930 succeeded production of prototype of split-anode type magnetron. Those
research had faced various difficulty, and therefore was quite difficult. But after our science
research, products having sizable output such as MN-701, It wasMN-702, etc. werecompleted.
c. Completion of various new products
The wireless industry in Japan showed tremendous progress owing to complete
domestic production of vacuum tubes, and it made high-power communication age realized,and active short wave era has arrived. This is solely result of progress in vacuum tubes, andhere, too, happy to see contribution of our company.
In 1934, Cymotron UV-171 used in 150kW transmitter for Tokyo central broadcast
station has produced. This was a high power product which a step advanced than UV-169
introduced in previous year, and marked world record class in its capacity.
Its size was: max. length: 165cm, max. diameter: 26cm, filament： 43V/500A, μ: 15, max.
Ep: 18kV and Gm: 40mS. Completion of UV-171 must show evidence of success in researchand production activity of our company.
About this time, R & D staff in the world were paying huge effort in UHF and SHF field.
It was when no country showed success in product reaching desired oscillation frequency
and large output power, but we challenged toward the direction by improving process insmall water- cooled tube.
Namely, small water- cooled tubes are much smaller in size compared with existing
natural cooled tubes, yet anode dissipation gets much higher. Cymotron SN-209C, SN-601

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and SN-605 have no difference between smaller version of large water cooled tubes.
In the other hand, Cymotron SN-610 introduced in 1934 modified shape of anode bottom tosemi-spherical, and made efficiency higher by utilizing the shape which was reducing total
area of anode surface much, thus obtaining much less static capacitance between anode andgrid. This was evaluated as an excellent tube for UHF application.
In the same year, a triode SN-603 was manufactured as suited for generating electronic
vibration, and many other newly designed transmitting tube were born. For aircraft
application, UX-860C which has designed for rigid internal construction and weightreduction. As a tetrode, UV-815 which works with relatively low anode voltage of 2,000V
and have nearly 1kW of output was made. Also a water- cooled tube UV-822 with output
reaching 4kW and rated as largest tetrode at that time was also marketed in 1934. Those
tubes were example of ones which kept steady improvement in the transmitting tube groupwhich were outside the fame of UHF and high power.
In the other area, application range of grid-controlled discharge tube names as
Thyratron has expanded, and in 1934 TX-902 was used for mobile color writing of mazdabuilding and let a newspaper Asahi introduced as a new noted site in Tokyo. For smaller
thyratron, Argon-filled types have utilized generally, and TX-902G, TX-903G, TX-911G,
TX-931G, etc. were marketed.
In 1935, R & D project in UHF and SHF region have expanded further, research on
magnetron has accelerated. As the first trial, water- cooled magnetron MN-710 having
500W order of output at around 50cm of wavelength has offered for research in many areas.
For less powered area, split type graphite anode model was born.
In around 1935, existing transmitters were still with triodes or tetrodes, but incooperating the pentode area in the receiver industry, pentodes were gradually adopted in
the transmitters as a trend, and its true value was recognized especially for aircraft andmobilized wireless equipment. We have marketed smallest powered UY-47D and UZ-47H,
10W class: UY-510A and UY-510B, 50W class: UY-511B, and for 200W class: UV-1083 andUV-1085. Introduction of those pentodes brought less number of tubes and smaller sizedsets as much as one-third possible, and therefore gained popularity. This promised that
future mobilized and small transmitters adopt more pentodes, and pentode era will arrivein transmitter field.
Application of grid controlled discharge tubes to high-powered communication systemhave also shown quick progress, higher powered models were demanded, and thyratron
TV-921 was introduced. Also Mercury-Bathed Rectifier (Ignitron) for high powered
communication has started as first trial in Japan, and IH-2001 and IH-2002 have
manufactured.

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Among the products during 1935, the most notable one was a thyratron TV-926. Thiswas designed as power rectifier for Tokyo’s 150kW transmitter. It had rating as PIV: 18kVmax., and average anode current: 30A. It was installed in Tokyo’s broadcast station, andcompared with a steel-bath type mercury rectifier, and its stable operation and highreliability were confirmed.

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Example of Transmitting Tubes: Part 1① UV-204A ② UV-203 ③ SN-204 ④ SN-208C⑤ HV-951⑥ UX-860 ⑦ HV-972

6⑧ UV-861 ⑨ HX-966

Example of Transmitting Tubes: Part 2①SN-205C⑥ UY-511B② SN-610 ③ UY-510B ④ UV-815 ⑤ SN-209C⑦ UV-1083 ⑧ UV-1085

7⑨ IH-2001⑩ IH-2002

Example of Transmitting Tubes: Part 3

UV-169 (200kW Input) and SN-209C

Thyratrons
Left: TV-916
Right: TX-911

8UV-171 (400kW Input)