all of the NIIIS-KA staff were sent 3,200 km away to Bukhara, joining the remainder of the LEMO as it also moved. Because of the null-reading method of analyzing the signals, the Zenit system suffered from slowness in measurements (38 seconds for determining the three coordinates) as well as accuracy. It also had a large dead zone caused by ground returns. While still at Kharkov, work had started on Rubin, a system intended to correct Zenit deficiencies. With Slutskin as LEMO Director, this project continued at Bukhara under Usikov's leadership. A new magnetron was developed; this operated at 54 cm (470 MHz) with a pulse-power increased to 15 kW. A gas-discharge transmit-receive device (a diplexer) was developed for isolating the receiver from the direct transmitter pulse, thus allowing the use of a common transmitting-receiving structure. (A similar development had been made for the RUS-2 common antenna, but this would not have been suitable for the microwave Rubin.) Several techniques for replacing the null-reading methods were considered, with the final selection making use of a fixture to provide a stationary dipole against which the directional position of the antenna could be continuously determined. Range, azimuth, and elevation were shown on a cathode-ray tube display. There was no provision, however, for feeding this information into an automatic unit for aiming searchlights and guns. Separate transmitting and receiving dipoles were at the focus of a 3-meter paraboloid reflector. The antenna assembly, with remote controls, could rotate 0–90 degrees vertically and 0–400 degrees horizontally. The width of the main beam was 16 degrees equatorial and 24 degrees meridian. The system was carried on two trucks, the electronics and control console in one and the power generator in the other. Both the transmitter magnetron and front-end portions of the receiver were in sealed containers attached to the rear of the reflector. The antenna assembly was on rails and could be rolled out to near the truck. By August 1943, the prototype Rubin system was completed, with all of the work performed by the small LEMO and NIIIS-KA staffs. The system was transported to Moscow where Usikov, Truten, and others conducted further tests and gave non-combat demonstrations. By this time, the British GL Mk II and its Soviet replication, SON-2, were also available and were possibly used in direct comparison with the Rubin; if so, the Rubin would not have fared well. Rather than releasing the