Development of the DBS band, 1,250 watt CW, air-cooled helix TWT

Abstract

Communications and Power Industries (CPI) has developed the VTU-6398D9A, a compact, high Continuous Wave (CW) power, high efficiency and forced air-cooled helix vacuum electron device. The new product was developed in 2017 to serve the demanding Direct Broadcast Satellite (DBS) Satcom market. The helix Traveling Wave Tube (TWT) operates with a 1,100 MHz instantaneous bandwidth and covers the full extended DBS band of 17.3 to 18.4 GHz. The minimum CW RF output power is 1,250 watts. The small signal gain is typically 49 dB, and the total gain variation over the full extended band is typically less than 1.5 dB. High overall efficiency is obtained by using a robust two-stage depressed collector and selecting operating voltages that simultaneously increase efficiency, reduce prime power, and maintain low body/helix current. Prime power is typically 3,995 watts. Low internal operating temperatures are achieved by way of advanced forced air heat exchangers. The TWT has overall dimensions of 5 inches wide by 20 inches long by 6 inches tall and weighs less than 30pounds. The predicted and measured performance data are compared.