In early 60s, due to the development of transistor technology, the request to make the Type Eight One transceiver smaller and lighter could be materialized. The development of Type Eight One Compact was started in early 60’s. In 1966, the new radio started to appear in PLA for trial use. Its size and weight were only half of that of Type Eight One. In late 60s, the Type Eight One Compact is certified. It is one of the Chinese second generation military wireless communication devices. It is 100% designed and made in China. It equipped division and regiment level infantry unit.
The feedback from the troop was mixed. Troops welcomed this much smaller and lighter radio; however, this radio faced a list of technical problems. On top of the list was that the transistor in transmitting amplifier stag was very easy to get fried. To solve this long list of issues, manufactory had been working on improved versions for 10 years. In early 70s, The Type Eight One Compact (A) is certified. The amplifier transistor issue was still exists. Starting from March 1972, a campaign was launched included a number of manufactories and research institutes, this problem was finally resolved after 6 months of intensive R&D. Then Eight One Compact (B) was certified in May 1973. The B version is the mostly produced version in Eight One Compact series, and most of the issues are basically resolved, but not completely.
In mid of 70s, the Type Eight One Compact (C) was certified. This is the last version and most successful version. It won a national award in 1978. However, in late 70s, the analog AM transceiver saw its end. It soon would be replaced by IC chip based third generation SSB transceiver. My sample is a C model, it was made in 1977.
Type Eight One Compact is a short ware AM transceiver covers 1.6 to 12 MHz in three bands (1.6-3.0, 3.0-6.0 and 6.0-12.0 MHz). Like the early production Type Eight One transceiver, it has transmitter and receiver built into one aluminum enclosure. A battery box is attached to the bottom of this enclosure. The transmitter and receiver power up separately and could work independently. The receiver is based on 139A/B receiver. The Type Eight One and mod A are based on 139A, and B and C versions are based on 139B receiver. The transistor for transmitting amplifier stag is built into the control panel. There are two in C version; one is an extra in case the one in use is fried. You can easily replace it without opening up the radio.
Type Eight One Compact is a 15W transmitter in high power CW mode and 3 to 10W in low power CW mode; it has 4.5W power in voice mode. It weight 12 kg with battery, telegraph key, headset and 1.5 meter antenna. The dimension is 390 X 280 X 115 mm. It could use 1.5 meter rod type antenna with a five star radiator and a configurable inductance coil to increate its effective height (this antenna is the same as that of the Silicon 2 W, however, a newer rod type antenna was introduced with Mod C, it does not has the five star radiator and the inductance coil and it is easier to setup), 20-meter wire antenna or 44-meter dipole antenna. The radio is powered by a 24V Ni-Cd rechargeable battery, which is built by 20 C type cells in an aluminum enclosure attached to the bottom of the radio. With this battery, the radio could work for 6 hours with 3:1 receiving/transmitting ratio. It could also powered by 24V external power source including 24V hand crank generator.
Operation of the receiver is straight forward; it is similar to that of the tube 139 receiver. An antenna tuning knob is added. Other than that, operation is same as that of tube 139. There is a little catch; there are two power switches, one on the receiver panel, the other one on the microphone handhold with the headset. When you use the headset, you have to turn on both the switches. Why is that? It is because that instead of standard headset, you also could use an earphone set connect to the receiver panel. In this case, the switch on the receiver panel makes sense. However, the sound from this receiver is pretty hush comparing to that of tube 139.
Operation of the transmitter is much simplified comparing to that of the tube Type Eight One, however, to tune the transmitting amplifier/antenna, you still have three knobs to turn. Training is needed before you can play with this baby.
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Excellent information.
ReplyDeleteOne problem with the 81 set is that after using the low power NET function to hear the transmitter in the receiver, the high power transmitter frequency shifts. It is very difficult to get the 81 set onto a desired receiver frequency ... a complaint by many users in the USA.
The 73B set does not have that problem.
I bought one of the identical receivers type 139A and found the acid core solder used in assembly caused many of the component leads to rot off.
ReplyDeleteMaybe this was an act of sabotage for the radio would have worked for a while and then died.
Jim