ANTENTOP- 02- 2004, # 006

UW3DI- the Timeless Transceiver

Schematic of the transceiver UW3DI at first time was published in 1970 at a Soviet ham magazine Radio # 5-6. The transceiver was named UW3DI by the callsign of its author, Jury Kudrjavtsev. Jury probably did not ever suspect, that his transceiver would be the most popular transceiver in the USSR and tens thousands copies of the transceiver would be made by Soviet hams.

Transceiver UW3DI was intended for work on cw/ssb at 80, 40, 20, 15 and 10 meters. The range of 10 meters was broken on two bands, 28,0- 28,5 and 28,5-29 MHz (when the WARC was obtained UW3DI got them also). Sensitivity of the receiver at ratio signal/noise of 10 dB is close to 0,5 μV. Power going to anode plate is close to 100 Wtts. Transceiver UW3DI contains 15 tubes and 24 semi-conductor diodes. At 21 exhibition of Creativity of Radio Amateurs, Moscow, the USSR, the transceiver took 1 place.

Later, in 1974, Radio was published a new schematic of UW3DI, known as UW3DI-2.

Igor Grigorov, RK3ZK

UW3DI (Radio #5, 1970)

Local collectives of radio amateurs developed their own variants of UW3DI known as UW3DI-3, UW3DI-4, Donetskiy UW3DI, Krasnodarskiy UW3DI. Certainly, the classical variant is UW3DI-1, by Radio #5- 6, 1970.

Well, UW3DI is the most popular transceiver in the former USSR. Unfortunately, I do not have exact statistics on use of the transceiver by hams, but USSR's magazine Radio wrote, that in 70s approximately 75 percents of Soviet hams used the transceiver, 60 percents of Soviet hams used the transceiver in 80, and approximately 40-50 percents of Russian radio hams used UW3DI at 90s of the 20 Century. Recently at the 21 Century, only about 25 percents of Russian radio hams used UW3DI because wide spread of used Japanese transceivers and surplus military radio equipment. UW3DI was the constant member almost all of USSR's radioamateur expeditions. Till now UW3DI takes part at lots of radio

expeditions.You can wonder, what gives to UW3DI such great popularity among hams. Certainly, it is simplicity of its circuit, good repeatability, and opportunity to reach high parameters by simple methods. Even an inexperienced ham can get good results making UW3DI. Probably, practically each ham of 70- 80s have made own UW3DI. By me was made two UW3DIIt was a very good practice for making and adjustment of the radio amateur equipment.

Till now, as I think, it is not present any alternative for UW3DI. In Russia there is no such simple and repeated transceiver. I can not understand, why lots of hams instead of doing the reliable tube UW3DI have started to do bulky transceivers on semiconductors. In a result, we have in the Air thousand of lame transceivers radiating poor signal

UW3DI (A ham design of 90s)

Correctly adjusted UW3DI has very good signal, as a rule, UW3DI has no TVI. Many times I have seen as in the same room a ham uses an UW3DI with a wire antenna, and his family watches TV free from any interferences.

Certainly, UW3DI is timeless transceiver and it leave for ever in memory of Soviet and Russian hams.

73! I.G.

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