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one set of contacts in this relay complete the coil circuit to
K703,
an auxiliary relay.
When this relay closes,
its contacts
complete the coil circuit to K805, which is the HV contactor.
K805 closes and completes the primary circuit to the HV plate
transformer;
thereby,
applying voltage to the amplifier.
There are some facts about the driver which should be known
and remembered that will help in operation of tile equipment
and contribute to better operating results.
1.
Tuning of the plate circuit changes t . 0 effective electri-
cal length of the plate tank.
Increasing the spacing be-
tween the tuning vane and the plate tank line lengthens
the effective length of the plate line and lowers the fre-
quency.
Conversely, deci.easing the spacing will raise
the frequency.
2.
Switch,
S510
1
locat_d on the driver panel in the lower
left hand corner is provided for checking individual ca-
thode currents of V301 and V302.
The balance contr1, R504 and R505,
is provided on the
front panel to enable the operator to maintain a balance
of plate currents.
When S510 is in mid position the me-
ter, M503,
is reading total plate current of V301 and V302.
The sum of plate currents as indicated by switching S510
either left or right of the mid position is not equal to
the total plate current as indicated on M503 when this
switch is in the mid position.
When S510 is switched
either left or right of mid positio ,
the metel' is reading
cathode current of that particular tube.
The switch must
be left in the normal or mid position while the transmit-
ter is operating except on initial tune up or for checking
balance between tube plate currents.
S512 is a multi- meter switch, which is used to read either
total grid current or individual screen currents of the
driving amplifier tubes.
Protection against electrical shock,
from high voltage cir-
cuits,
is provided for by door interlock switch, S514.
When the back door is removed, S514 will open and innedi-
ately remove the high voltage from the amplifier.
When
S514 opens,
relay K502 is de- energized and opens the hold-
ing circuit on K503.
Therefore,
removing the primary plate
voltage from the high voltage transformer.
These are some facts about the amplifier which will contribute
to better operation.
6/22/ 61
-16-
FM- 20B
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