d. 90 Phasing Discriminator, 60W/6W Power Level Network, Meter Function Switch and
The 90 phasing discriminator
by two voltage sample inputs, one from the coupling
and resonator and the second from the central resonator. Voltage sample V1 appears in the
secondary of transformer T3 as two equal voltages but 180 out of phase with respect to the
center tap. The second voltage sample V2 is coupled to the center tap of transformer T3 through
transformer T2. Therefore, when V1 and V2 have a 90 phase relationship, the dc voltage appearing
across potentiometer R9 is equal in magnitude and opposite in polarity with respect to the wiper
of potentiometer R9. The total voltage across the potentiometer is zero. As the phase relationship
of voltage V1 and V2 change, the total voltage across potentiometer R9 is either positive or
negative depending on whether V1 leads or lags V2 by more or less than 90. The magnitude
depends on how greatly the angle between V1 and V2 differ. A bridge rectifier is connected to the
output of the discriminator. This provides unidirectional voltage output for the metering circuitry.
For example, the output voltage of the bridge circuit is zero for a 90 phase relationship between
V1 and V2 and positive going for any deviation from 90 between the two voltage samples. The dc
voltage is then sent on to the 60W/6W power level network.
e. 60W/6W Power Level Network. The 60W/6W power level network consisting of resistors R7,
R8, R12, and R13 provide the values needed to give a voltage ratio equivalent to 60W: 6W for
f. Meter Function Switch S1. The meter function switch S1 located on the front panel selects
forward power, reflected power, and phasing at a 60W level or a 6W level. The output is then sent
to the meter.
g. Meter M1. Meter M1 has two scales. One is a 60W scale and the other a 6W scale. The
scale used is determined by the meter function switch located on the front panel. Meter
movement corresponds to the meter function switch position.