User's Manual

5-10

5.8 METER/SWITCH BOARD A12 (81947) and DISPLAY BOARD A13 (81952)

This board contains the metering circuits for the front panel meters. A12S1 selects the

parameter to be monitored. This selection is then sent to multimeter M1. The multimeter has

three calibrated scales for measuring plate voltage, screen current and forward or reflected

RF power. The KW scale should be divided by ten when measuring reflected power.

A12U1 samples screen and control grid current and drives the appropriate LED to indicate

excessive current of either screen or control grid. Q1 samples forward RF power voltage

from the SWR board. This voltage is peak-held by C8 and sent to U2 to drive the peak

reading display LEDs on DISPLAY BOARD A13.

FIGURE 5-13 METER/SWITCH BOARD (ASSEMBLY A12) COMPONENT

LAYOUT VIEWED FROM FRONT PANEL SIDE

FIGURE 5-15 DISPLAY BOARD (ASSEMBLY A13) COMPONENT

LAYOUT AND TOP CIRCUIT VIEWED FROM TOP

U1 GRN

U2 GRN U3 GRN U4 GRN U5 GRN U6 GRN U7 RED