As in the case of the PG-1, the plate current milliammeters for indicating the plate current of the UV-845
tubes should be equalized, that is, the reading of the milliammeter labeled "IP BACK TUBES" on the
power amplifier panel should equal the reading of the milliammeter on the same panel labeled "IP
FRONT TUBES." The plate currents are controlled by means of the grid bias controls located at the
bottom of the amplifier panels. These controls are labeled "BACK TUBES IP CONTROL" and "FRONT
TUBES IP CONTROL". The readings of each milliammeter should be approximately 130 milliamperes. If
one tube is burned out, the milliammeter in its circuit would read 65 milliamperes. Do not attempt to
equalize the readings with one tube burned out.
When the voltages have been checked and properly adjusted the amplifier equipment is ready for
operation except for turning "on" the stage loudspeaker switch.
184. Troubles on the PG-2 Equipment. -The troubles which might occur on this equipment are similar to
those which were discussed in section 177 for PG-1 equipment.
Section 177 applies equally well to the PG-2 equipment with the exception that in case a UV-845 burns
out in the PA-5 amplifier the milliammeter reading will drop to half its normal value.
The location of the fuses of the PA-5 amplifier rack is shown in Figure 118. It will be noticed that the PA5 rack has two 1000 volt fuses, instead of one as used on the PA-1 rack. These two 1000 volt fuses are
rated at one-half ampere each. One fuse is in the 1000 volt line to one power amplifier, and the other fuse
is the line to the other power amplifier. The location of the fuses at the motor-generator set are the same
as described for the PG-1 equipment in section 177.
(B) PG-1, 4, 6, 7, 8 AND 10 EQUIPMENTS
(Partially Socket Power Operated)
185. General Description of the PG-3, 4, 6, 7, 8 and 10 Equipments. -The PG-3, 4, 6, 7, 8 and 10
equipments are all SPU operated. As stated in Chapter X the
designation SPU stands for socket power unit. This designation is given to the power amplifier units
which obtain their plate and grid voltage supply from rectified alternating current. The rectifying devices
are built into the power amplifier units, making each of these units complete in itself.