6715D/Rev. Jul.2020
Page 9
Altronic Research Inc.
switch is "ON" or when one of the fan thermostats senses a temperature equal to or greater
than 120
°
(
±
7
°
) F.
The transmitter interlock circuit consists of two thermal switches wired in series to control
the interlock relay. Power is supplied to this relay whenever the equipment is attached to
the correct power supply and the motor temperature senses a temperature equal to or less
than 160°F and the resistor compartment temperature switch senses a temperature equal to
or less than 250°(±7°)F. A lamp is provided to indicate when one or more of the over-
temperature switches opens. It is labeled "OVERHEAT", indicating a change in state of
the interlock.
1-6. Mechanical Description.
The Model 6715D RF Coaxial Load is a 50-ohm non-reactive
resistor assembly which is cooled by forced ambient air. The blower assembly is a 1/3 HP
direct-drive centrifugal blower depending on the voltage rating of the load. The blower
moves air from floor level into a closed plenum surrounding the resistor assembly. Air then
enters the resistor assembly and flows downward through it to the transition duct and then
out of the enclosure via the discharge grill. This places the RF input connector at the
coolest point in the air stream and affords exceptionally quiet operation.
1-7.
General Principle of Operation.
After ascertaining that the Model 6715D is connected
to the correct power supply, connect the transmitter interlock circuit and RF source. Turn
the main power switch ON to start the fan and enable the transmitter. Operate the
transmitter as desired. To stop operation, it is necessary to first turn off the transmitter,
then the main power switch on the Model 6715D. The fan may continue to run for some
time. This depends upon the power level at which the load was operating and upon the
ambient air temperature. This feature is necessary to prevent damage to the load. The
Model 6715D can be operated in a "Standby" or "Reject" mode with the blower off.
Current draw in this mode is 60 milliamperes. To operate in this mode, connect the unit
as before and leave the main power switch on the front panel "Off". It is highly
recommended that the normally open pair on the interlock terminal board be used to
control a user-supplied alarm circuit. This pair will close on power failure or overheat
and the alarm, if independent of the AC power supply for the unit, will notify the
operator of a fault.
1-8.
Operating and Adjustment Controls.
The only operating control is the main power
switch. No field adjustments are necessary or possible.