The Type 92 Field Phone.

The Type 92 field phone is commonly encountered in collections around the world and most collectors have at least seen images of one. Even though the Type 92 is so common, not much information exists that explains their origin or use. Field manuals for these field phones do exist, however, none have been translated into English yet. A field phone serves the same battlefield function as a radio but is not wireless. While a field radio transmits voice and data over radio waves, a field phone uses a wired connection. To communicate with a field phone, a wire must be used to connect two or more units together. This communication wire generally comes on spools. USGI communication wire comes on 1000-foot (300 M) spools, and I suspect Japanese wire spools were of a similar length.

Left: Type 92 field phone in use. Right: A Japanese operator sends Morse code messages on a Type 95 radio.

All armies during the Second World War employed field phones for close communication. The advantage of field phones over radios is that they could be made smaller and cheaper than military radios of the time and were quite portable. The disadvantage of course is that you are limited to the distance that you can communicate, and communications could be interrupted if the wire was cut or destroyed, common during artillery barrages. The Japanese military did of course use field radios for longer-distance communication, but these units were large and expensive and were usually employed at higher-level headquarters. Radios have been seen in period photos being used in field conditions in more forward positions. The Type 92 field phone comes in a handful of varieties, most of which are just differences in construction and the style of latches used to close the lid. There are, however, two major types of field phones. The first, and most common type used a series of three electromagnets connected to a spindle. A hand crank is connected to the spindle, and when turned, the magnets generate an electric current which is sent down the wire to the next field phone unit. The electrical current rings a call bell for the next operator to know they have incoming traffic. The call bell can be turned off by use of a disconnect switch so as to not give away your position if enemy forces are nearby. The second type of field phone uses a generator box in place of the three large magnets but functions the same way.

Electromagnets.

Generator box.

Left: Electromagnets. Right: Generator box.

Disassembled handset. The perforated disk is the voice mic, and is inserted with the perforations facing toward the inside of the handset.

The most prevalent version of the field phone is made of a rectangular wooden box with a hinged aluminum lid. The lower box portion contains the main working components of the field phone such as the electromagnets or generator, batteries, fuses, call bell, spare parts, and tools. The upper portion holds the handset and extra earpiece, as well as the connection points for the communication wire. The handset is constructed of cast aluminum with a hollow base and plastic earphones. Many field phones come with an extra earphone for a second person to listen in, and mine does come with this feature. Interestingly, these field phones also have a Morse code key on the rear of the unit. Japanese Morse code, referred to as “Wabun code”, works under the same concept as traditional Morse code except for the different combinations of dots and dashes that correspond to a Japanese Kana character, which can then be used to spell out words.

Two sets of original Japanese batteries.

Type 92 field phones were carried in either a leather or rubberized canvas carry case. The carry cases came with a shoulder strap for ease of transport. The case lid generally contains a storage pocket, and loops on the front of the case hold the grounding stake. As mentioned previously, the type 92 field phone came with various accessories that were stored either within the phone itself or in the carry case. The front of the field phone box can be opened to reveal its internal workings. Within the main compartment are two 1.5-volt batteries that are wired in series to provide a total of 3 volts. These batteries provide the power to transmit voice or morse code messages. Original Japanese batteries are very rare and I’m fortunate enough to have two different pairs. About two years ago I made replica type 92 field phone batteries that could accept a AA battery. AA batteries are 1.5 volts, so connecting two replica batteries in series would yield the proper 3 volts needed to run the phone and communicate with another unit. I’ve sold all the replica sets I made but do plan on making more in the future. Eventually, I would like to get a second field phone and have the two talking!

Reproduction batteries wired in series to produce 3 volts.

In most field phone sets, a detachable fuse board is held in place next to the batteries. This fuse board holds two fuses and can be attached to the main posts under the lid during rain or inclement weather and has an attachment point for the grounding stake. This fuse board in combination with the grounding stake serves to protect the phone and its user from lightning strikes. The brass grounding rod attaches to the main wire posts and is driven into the ground. In the event of a lightning strike to the communication wire, the electrical current will be mostly diverted safely into the ground, saving the operator. The two fuses on the fuse board will blow and prevent damage to the phone unit. Next to the fuse board is a small aluminum container that holds spare parts. Usually contained within this

space are spare fuses, extra battery wires, and extra parts of the earpiece. My spare parts also include very fine replacement wire to repair the fuses and clear perforated plastic sheets that slip between two mounting plates for the fuses. I am unsure exactly what these are for, but I suspect that they act as another barrier against electrical surges. Inside the bottom of the main box, a double-ended wrench is included with the phone. One end is 8mm and the other 6mm. The wrench is held in place with a metal tab and is spring-loaded. A screwdriver is nested inside a small holder next to the generator. In total, the complete phone unit with the carry case weighs approximately 13.5 pounds (6.1 KG).

Fuse board and grounding spike in use.

The Type 92 field phone served the Japanese military well for the duration of the Second World War and many units came home as souvenirs with Allied servicemen. Field phone units can be found for sale with relative ease and in varying conditions. Generally, these units are missing their original batteries, but hopefully, soon I will be producing replicas again. Overall, I’ve found these field phone units to be high quality and built with innovative features. They are designed to be as simple as possible, and easily serviced in the field.