SP-200 Series Troubleshooting Data Data apply to BC-779-B, BC-794-B, and BC-1004-C Reference: U.S. Army TM11-866 TABLE 1 -- TUBE SOCKET VOLTAGES ---------------------------------------------------------------------------- | Socket Tube Voltage wrt GND at tube socket terminal number | | Number Number 1 2 3 4 5 6 7 8 | ---------------------------------------------------------------------------- X1 V1 0 0 250 135 135 6.3ac 0 X2 V2 0 0 250 135 135 " 0 X3 V3 0 0 250 115 " 0 X4 V4 0 0 150* 150* 150* " X5 V5 0 0 250 135 0 " 0 X6 V6 0 0 0 -43 0 135 " 250 X7 V7 0 0 0 -1.5 0 100 " 240 X8 V8 0 0 -.2 .4 -.2 " .4 X9 V9 0 0 .4 0 0 .4 4.0ac -.2 X10 V10 0 0 0 0 40 6.3ac 155 X11 V11 0 0 0 -1.5 0 110 " 240 X12 V12 0 0 -3.2 -3.2 -3.2 " -3.2 X13 V13 0 0 110 -3.2 " 0 X14 V14 0 0 240 240 -20 " 0 X15 V15 0 0 380 380 0 " 38 X16 V16 0 0 380 380 0 " 38 ------------------------------------------------------------------------------ Notes: Terminals 1 and 2 of all sockets are at zero potential with respect to chassis *Varies widely with different tubes; also with dial setting The above voltage readings are based on an a-c line voltage exactly equal to the primary tap on the power transformer -- higher or lower line voltage should result in corresponding variations in these readings. All d-c readings are based on the use of a meter having a resistance of 1000 ohms per volt, and are taken between socket terminal and chassis. Settings: SENSITIVITY and AUDIO GAIN should be set to 0 SIGNAL-MOD-CW switch should be on CW AVC-MANUAL switch should be on MANUAL SEND-REC switch should be on REC LIMITER switch should be ON TABLE 2. SOCKET TERMINAL RESISTANCE VALUES. (All measurements made between socket terminal and chassis) RECEIVER ---------------------------------------------------------------------- | Terminal | Pin | Variable | Resistance | | Name | No. | Ref No. Setting | in ohms | ---------------------------------------------------------------------- V1 grid Cap SW4 AVC 1,160,000 SW4 MAN 515,000 V1 plate 3 SW2 SEND infinity SW2 REC 20,000 V1 screen 4 11,500 V2 grid Cap SW4 AVC 1,160,000 SW4 MAN 515,000 V2 plate 3 SW2 SEND infinity SW2 REC 20,000 V2 screen 4 11,500 V3 sig grid Cap 510,000 V3 plate 3 SW2 SEND infinity SW2 REC 20,000 V3 screen 4 SW2 SEND infinity SW2 REC 43,000 V3 inj grid 5 50,000 V4 grid Cap 50,000 V4 plate 3,4,5 30,000 V4 cathode 8 0.1 to 1.8* V5 grid Cap SW4 AVC 670,000 /SW4 /MAN 14,600 \R56 \0 /SW4 /MAN 10,300 \R56 \10 V5 plate 3 20,000 V5 screen 4 11,500 V6 grid Cap SW4 AVC 670,000 /SW4 /MAN 14,600 \R56 \0 /SW4 /MAN 10,300 \R56 \10 V6 screen 6 11,500 V6 plate 8 20,000 V7 grid 4 10,300 V7 screen 6 68,000 V7 plate 8 20,000 V8 plates 3,5 217,000 V8 cathodes 4,8 250,000 V9 plates 3,6 250,000 V9 grids 4,5 1,220,000 V9 heater 7 4** V9 cathode 8 SW5 ON 117,000 SW5 OFF infinity V10 grid 4 100,000 V10 screen 6 SW3 CW 523,000 SW3 MOD infinity V10 plate 8 SW3 CW 73,000 SW3 MOD infinity V11 grid 4 10,300 V11 screen 6 68,000 V11 plate 8 20,000 V12 plates 3,5 35,300 V12 cathodes 4,8 300 V13 plate 3 68,000 V13 grid 5 500,000 V14 plate 3,4 18,600 V14 grid 5 500,000 V15 plate 3,4 19,400 V15 grid 5 320 V15 cathode 8 750 V16 plate 3,4 19,400 V16 grid 5 320 V16 cathode 8 750 --------------------------------------------------------------------- * Varies with band change switch setting ** with V9 removed from socket POWER SUPPLY Units RA-74-C, RA-84-B, RA-94-A ---------------------------------------------------------------------- V1 Plate 2 40 ohms (55 ohms for RA-74-C) V1 Plate 3 " " " " " " V1 filament 1,4 19,500 ohms V2 plates 2,3 28,500 ohms V2 filament 1,4 22 ohms (34 ohms for RA-74-C) -----------------------------------------------------------------------