Western Electric 407A-4, Instruction Manual

Page: 84 / 136

trol of the plate regulator from fully automatic
to manual control by means of push buttons K6F
and K7E. Leave in 1'Automatic 11 pos iti on.
DlOF - 110s c . Amp. Filaments tt - This switch operates a
contactor to supply power to the os cillator­
amplifier . Throw to "ON" pos ition to start and
operate transmitter.
DllF - 110s c . Amp. Control " - In the test pos ition this
switch permits operati on of the os cillator-ampli­
fier unit alone . The bias rectifiers for the
modulating ampl ifier and power amplifier are de­
energiz ed. In the operate pos iti on, the gate
switches and plate contro l of the oscillator ­
amplifier are tied in t o the control circuit of
the rest of the transmitter . Leave in the "Op­
erate " pos ition .
Dl2F - 11Protective Circu it" - This swit ch removes the
control power from the protective cir cuit .
Leave in 110N11 pos ition, except for tuning of
power amplifier.
KlF - "Rect . Fil. Delay Release" - A momentary-contact
push button to lock up S4F without waiting for
operat ion of delay re lays . May be operated in
an emergency after a power interruption when the
operator may prefer to risk a shortening of the
l ife of rectifier tubes in order to avoid los s
o f program time .
K2F - "Circuit-Breaker Reclose11 - This momentary-con­
tact push button may be operated to reclos e the
plate circuit breaker after it has been tripped
open twice in rapid succes sion and the recloser
will not operate automatical ly.
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