Japanese Naval Aircraft Radios
Navy Type 1-3 Transceiver
|The basic reference for information on Japanese Naval aircraft radios was
the document titled, "Operational History of Japanese Naval Communications: December
1941 - August 1945." which was prepared by the Military History Section of
Headquarters, Army Forces Far East. and was a translation from a document prepared by
Japanese officers for MacArthur's staff shortly after the war. This document covers all
aspects of naval communication from aircraft to submarines.
In reading the report, one
encounters the term "Experimental Manufacture" which seems to precede "Mass
Production". I take this to mean that the sets were made in some quantity by a
prototype shop before tooling and dies and detailed plans were turned over to a
manufacturing facility. Experimental sets were made in research and development
facilities, perhaps in quantities of two or three units for testing and evaluation and
when all design changes were completed, they were sent to an "experimental production
facility" (prototype shop) for limited production. Once the manufacturing process was
worked out and field testing was done, the plans and tooling would be turned over to a
In preparation for war, radio equipment as well as other war material depended solely
on production by civilian industries. In 1940, the Navy took measures to increase
production by establishing the NUMASU Ordnance Depot, which specialised in the manufacture
of communications equipment. By 1941, large scale equipping of aircraft was planned and
the production of necessary radio equipment was set forth according to a schedule issued
by the Navy General staff.
At the outbreak of the war, the installation aspect of communications equipment was
limited to installing equipment in any available space. The installation was carried out
with out careful consideration of the requirements in battle or the duties of the radio
crew during flight. Therefore, the efficiency of radio equipment could not be fully
manifested. This comment seems to ignore the fact that the Japanese had been at war since
the early 1930s in China.
In the installation of equipment on aircraft, the fitting of the radio was found to be
most defective, and the radio crew had to operate it under very adverse conditions.
Receiving was difficult or impossible because of the noise from defective telegraph sets
or buzzers and as a result, many important telegraph messages failed to be received. It
was also difficult to operate the telegraph key in a plane at a high altitude because the
radio set was poorly located and adjustment and tuning of the set was impossible.
The installation work by aircraft manufacturers was also unsatisfactory. In particular,
careless supervision and poor testing frequently resulted in wrong wiring and defective
high voltage to ground or bonding. One can only wonder what a high voltage spark would do
around aviation gasoline fumes. In many cases of defective wiring, the sets did not
function after they were installed in the plane and considerable time went into repairs
and maintenance. There were also a considerable number of aircraft on which the equipment
was absolutely impossible to repair. Another defect was the noise caused by improper
insulation and bonding of the ignition system; moreover in the installation there were
frequent cases in which the mounting bases were of a different size, necessitating
adjustments to be made. There were many factors resulting in the defective installation.
One factor was that the Japanese had considered the equipment more important than the
installation and there were no research personnel involved in studying radio installation
until 1944. Those people who were involved in radio research did not become involved the
actual equipping of aircraft. They only considered the weight, volume and capacity of any
equipment and were not familiar with the actual circumstances of those who operated it
Another factor was that electrical engineers, employed by aircraft manufacturing
companies and working on design and development of airframes knew very little about radios
or their operation. As for the companies themselves, they were forced to rush production
of communication equipment and as a result they deliberately scamper their work. Factory
superintendents were so occupied with procuring materials that testing of completed
aircraft, their primary duty, was neglected. I have never heard the word scamped, perhaps
it was a typo error or perhaps it meant scrimped.
The report went on to indicate that radio telephone was necessary for fighter planes to
carry out effective aerial combat and interception operations, but because of its limited
range, the pilots were disinclined to use it. This tendency was probably attributable to
the pilots indifference to radio and partly to imperfection of the equipment itself, but
the basic reason for the poor fighter plane communications was that there were very few
officers enthusiastic enough to overcome the drawback and make the best use of existing
With the appearance of the Type 3 No 1 aircraft radio set, radio telephone capacity
increased as it was simpler to manipulate but maintenance was neglected. Moreover, most of
the units had poor communication due to the lack of attention to the screening of
There was originally in existence the Type 96 No 4 A/C radio which could be operated by
remote control and was installed in large and medium planes. The Type 2 No 4 radio set was
experimentally manufactured for remote control purposes but it's mass production was
shelved because it was deemed impracticable. Since the Type 96-4 could not be operated on
Medium frequency, the Type 2- No 3 set was installed in Land bombers.
The "Operational History of Japanese Naval Communications: December 1941 - August
1945." went on to discuss air base radio communication but I will not include the
information here, as it is not really an aircraft set(s). In addition, they did not list
the nomenclature of air base radio sets. The only picture of a radio specifically
identified as a ground radio is shown here.
It has been said that Japanese aircraft made little or no use of voice radio. In
actuality the installation of voice radio appears to have been more widespread than might
be believed, although its actual use was much less so. Both the Official Report and Eric
Bergerud's new book on the South Pacific air war, "Fire in the Sky," note that
the Japanese suffered serious deficiencies in the manufacture, installation, and
maintenance of their radios, and that pilots, at least fighter pilots, often didn't bother
to use them. Bergerud views this as one reason for the rather chaotic melee tactics
employed by the Japanese in air-to-air combat; co-ordination
between aircraft was nearly impossible. (Keith Allen)
The report "Operational History of Japanese Naval Communications: December 1941 -
August 1945." breaks down Japanese radio development in to several Phases; The first
Phase did not have a date but seems to include 1941. These appear to have been the basic
radios in the main naval aircraft types in 1941.
Navy Type 96-3 Reciever Dynamotor PSU
Type 96-2 Vibrator Power Supply
Navy Type 3-1 Transceiver
Type 96-3 No 2
Imperial Japanese Navy
Type 98-4 Navy Aircraft Radio
Naval Paratrooper Experimental Radio
Type 99 Japanese Navy Morse Code Trainer
Type 99 Japanese Navy Morse Code Trainer, Data Plate
Navy Type 96-4
Pilot Training Receiver
Pilot Training Receiver Inside View
Japanese Aircraft Key
The partial list of sets under development includes
Type 43 No 1- Fighter planes 5,000-10,00KC, 100 watt, 500 mile range for fighter planes
No 3 Experimental A/C radio 1943 Modification 2,500 -10,000 and 300 - 500 KC, 300 watt,
1,500 mile range
No 5 Experimental A/C Radio, 1943 modification, 100-20,00 Al Wave 300 watts, 1,500 mile
Experimental Radio direction Finder, modified in 1943, 300 -500 KC 300 watts, 200 mile
No 8 Experimental A/C radio, parachute forces, 2,500-10,000KC 60 watts, 300 mile range.
Experimental Inter-phone, modified 1943, to be used in three seater planes.
The latter part of the third phase, (November 1944 to August 1945) indicates that in
order to meet the rapidly mounting enemy counteroffensive, the role of operational
communications became increasingly important. The most urgent problems were the need for
strict supervision over the increased output of carelessly manufactured equipment and the
need for immediate use of experimental equipment. By March 1945, such equipment had
undergone some improvement and was ready for practical use.
When enemy air attacks by B 29's increased in intensity, the plants manufacturing
vacuum tubes and other various parts were destroyed. In addition due to the drop in
productive capacity resulting in the dispersal of plants, the manufacture of equipment was
insufficient to meet the needs of front line forces. Later , in anticipation of the
Homeland operation in which all-out suicide attacks were to be carried out, the need for
simplified communication equipment for special attack planes was envisaged and efforts
were directed to the experimental manufacture of small-type radio sets for these planes.
The improvement and experimental manufacture of principle equipment was carried out
during the period just prior to the end of the war. On the other hand, manufacture of much
of the other equipment had to be suspended due to lack of vital parts.
The manufacture of certain sets was suspended, these were the Type 96-2, Improvement 2,
Type 96-3 improvement 1, Type 2 No 3, Improvement 1, and the Number 10 transmitter.
Improvement was made to the Type 96-4 Models 1 and 2; the experimental manufacture of
No 1 Experimental aircraft radiotelephone, 1944 modification and the Type 3 No 1 sets were
readied for mass production. Acceleration of mass production of the this set and the
experimental manufacture of a radio set for special attack planes, experimental
manufacture and test of the receivers exclusively for the Shusi, an interceptor plane.
There was also the experimental manufacture and test of an experimental radiotelephone for
inter unit communications and the acceleration of experiments on Experimental aircraft
radio homing direction finder, modified in 1944.
The history notes that the Japanese found it necessary to train their fighter pilots to
use Morse as well as voice, for long-range communications. None of the tables of aircraft
equipment mention the installation of CW radios in fighters, however. Given the apparent
reluctance of Japanese fighter pilots to use radio of any kind, I doubt they spent much
time banging out Morse on combat missions. (Keith Allen)
As can be seen from the pictures, some of these sets can be found by collectors but they
are very rare sets and command premium prices. Since most aircraft radios went down when
the aeroplane crashed, they did not survive. Those sets which can be found were most
likely captured on airfields that were captured by ground forces.
The Air Technical Intelligence Unit of the U.S. Army Air Corps captured numerous
aircraft when they were in operation and gained access to a lot ore when they occupied
Japan. Their primary interest was the aircraft, power plants, etc and did little with the
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