Section III
Paragraphs 3-10 to 3-11
R-1422, R-1423, C-1405 and C-1406, is a network so
schematic shows the connections in the 90 cps circuit
proportioned that the resistance in the circuit is equal
when the AUDIO SELECTOR is set to 90
to the capacitive reactance. This network is switched
that the circuit is identical to the Tone Localizer
by means of S-1401 between various taps on T-1401 .
circuit of figure 3-4 with one exception (1) the input
See figures 3-6 and 9-1. For example, in the 90 degree
grid of V-1404 has been shorted to ground to kill the
position C-1405 and C-1406 are connected to terminal
150 cps signal. With this connection 20% modulation
4 while R-1422 is connected to terminal 7. The output
of the network is taken from the center point between
at 90 CPS is obtained when the LOC-GS control is set
R-1423, C-1405 and C-1406 and fed to the grid of the
in the middle of the white center sector on the panel.
30 cps variable phase amplifier V-1401A. A 90 degree
position the 90 cps signal is disabled and
phase relation exists between the voltage at the grid of
20% modulation at 150 cps is obtained when the LOC -
V-1401A and the secondary of the transformer for this
GS control is set in the middle of the white center
particular connection. For 270 degrees the network
sector on the panel.
is reversed. For the 45 degree position the network
is connected across only one secondary winding of T-
1401. For O and 180 degrees both ends of the network
azimuth steps are provided in VOR operation. These
are connected to either terminal #7 or to terminal #4.
eight steps spaced 45 degrees apart are obtained by
This switching results in the required 45 degree steps
shifting the phase of the 30 cps variable phase signal in
but causes the output voltage on the grid of V-1401A in
an RC phase shifter while maintaining a 30 cps refer -
some positions to be only .707 of the voltage in the
ence signal of constant phase on the grid of the frequen-
other positions. This variation in level is compensated
cy modulator V-1407B. The phase shifter, consisting of
by selecting taps on the cathode resistor of V-1401A
14
