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In the lower left-hand corner of the panel is a "START-STOP" push-button station for controlling the motor of the motor-generator set. A pilot lamp to the right of the push-button station is lighted when the motor-generator set is running. The push-button station controls an electrically operated motor line switch as described in section 36.

In the upper left-hand corner of the panel are two jacks. One is labeled "EB123X100." This jack is used to read the plate voltage of the three tubes in the voltage amplifier. The jacks directly below this is labeled EB413X100. This jack is used to check the plate voltage of the UV-845 tubes (tubes 4 to 13). At the right of the panel are two more jacks. One is labeled ECX50. This jack is used to measure the voltage of the 250 volt generator (not the grid bias of the 845 tubes). Although the 250 volt generator is used to supply tile grid bias voltage for the UV-845 tubes, the actual grid bias is controlled by means of the grid bias controls described in the preceding section. The other jack on the right-hand side of the panel is labeled "EAX2", and is used to read the voltage of the 15 volt generator. This voltage is also the filament voltage of the UV-845 tubes.

All fuses of the rack are located at the back of this panel. Figure 116 shows the location and sizes of the various fuses used. Do not remove or replace any fuses without first stopping the motor-generator set used in conjunction with the rack.

171. Description of the PA-1 Power Control Panel. -The second panel from the bottom is the power control panel. Three field rheostats are mounted on the rear of the panel, with their controls brought out to the front. The knob on the left controls the voltage of the 1000 volt generator. The center knob controls the voltage of the 250 volt generator, and the knob on the right controls the voltage of the 15 volt generator.

The field current for all three generators is supplied by the 250 volt generator. It is, therefore, important that the 250 volt generator voltage be correct at all times. This voltage may be checked at the jack on the metering. panel marked "ECX50". If it is necessary to adjust this voltage, watch the plate current milliammeters to see that the plate current does not rise above normal. Keep one meter plugged into this jack, when adjusting the voltage of either one of the other two generators. See that this voltage does not change. If it does, correct it before making any further adjustments on either of the other machines.


Chapter Thirteen Pages
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