Power Supply Circuits
Filament voltage for the amplifier tubes (V1 and V2) and the rectifier
tubes (V3, V4 and V5) is supplied from filament transformers T3 and T2
respectively. The 220-volt primary voltage for these transformers and the
200-volt grid bias voltage are obtained from the associated transmitter, where
they are adjusted to the proper value.
The plate supply consists of a 3-phase mercury vapor rectifier and a
single section filter. The primary windings of the three-phase high-voltage
transformer (T1) are tapped to provide adjustment of the high-voltage supply.
The center tap of the secondary of this transformer (T1) is connected to ground
through the coil circuit of an overload relay (S3). The high-voltage direct
current is indicated by a voltmeter (M3) and the current drawn by the amplifier
is indicated by an ammeter (M5).
Control Circuits
The control circuits of this amplifier operate in conjunction with some of
the circuits of the associated transmitter to provide the necessary sequence of
switching operations.
The power supply switch (D1) is a three-circuit main line switch for the
high-voltage rectifier. It supplies power to the contacts of relay S1 which
completes the primary circuit of the high voltage transformer (T1). The plate
supply switch (D2) is connected in series with the coil circuit of relay Si, which
is energized with power supplied from the associated transmitter when it is
operating. The contacts of the overload relay (S3) are connected in series with
the overload relay of the associated transmitter so that if either relay mo-
mentarily opens when the transmitter is operating, both equipments will be
turned off and cannot be started again until the plate control switch of the
associated radio transmitter is turned off and on.
The door switches (D3.1 to D3.5 inclusive) are connected to circuits in the
associated transmitter so that when any door is opened the high-voltage supply
in both units is removed.
Relays S2 and S4, and resistance R1 constitute a protective circuit for
reducing the initial charging current of the filter condenser (C1). Resistor
Rl is automatically connected in series with the filter condenser (Cl) while
it is being charged, thus protecting the rectifier tubes from a heavy surge of
current when the equipment is turned on. The relays operate as follows:
When the plate supply of the amplifier is turned on, the condenser charging
current operates relay S4 through resistor Rl. When condenser Cl is fully
charged, the charging current stops, relay S4 releases and relay S2 operates
and connects the negative terminal of the condenser (C1) to ground.
INSTALLATION
Dimensions of the amplifier and the location of terminal blocks are shown
on Figure 4. Sufficient space should be allowed around the amplifier, partic-
