MIL-H-80045B
brazing, soldering, hardening, and melting. The rated RF power output of
the heaters shall be expressed in kilowatts (KW) available at the work
station under continuous duty operation, The rated output shall be not
less than that shown for Types and Sizes in 1.2.
3.5 Components.
3.5.1 Controls. The heater controls shall consist of no less than a
main power circuit breaker, plate power off-on contactor, variable grid
excitation control, plate overload reset control, grid overload reset con-
trol (unless otherwise protected), and output power control. Except for
the main power circuit breaker, all controls shall be located on the front
of the heating unit and mounted so that they are easily accessible to the
operator. All controls shall be identified by permanent marking in accord-
ance with the manufacturer's standard commercial practice. When specified
(see 6.2.1), a foot off-on control switch for alternate control of output
power shall be provided. The foot switch shall be equipped with a
standard length cable, suitable for the purpose. Connection of the foot
switch to the heater shall be by a quick disconnect plug and receptacle.
Power "off" devices shall be in accordance with IEEE Standard No, 54.
3.5.2 Output power control. Unless otherwise specified (see 6.2.1),
stepless thyratron or silicon controlled rectifier (SCR) power control shall
be utilized. Control of the output power to the load shall be continuously
variable from zero to 100 percent of rated output, On three phase heaters,
the control shall be manual and have the capability of accepting a standard
DC input signal from a temperature controller of either O-5 or 4-9
milliamperes (Ma).
3.5.3 Timer. A timer shall be provided for automatically controlling
the heating cycle. The timer shall be calibrated in increments of one
second, from zero through a minimum of sixty seconds, with a repeat
accuracy of plus or minus 0.25 percent. When specified (see 6.2.1), an
electronic keying device for precision control of short heating cycles
shall be provided. The heater shall be designed for both manual or auto-
matic control of the heating cycle.
3.5.4 Voltage regulation. Filament voltages shall be maintained within
Plus or minus 2 Percent of rated value for Plus or minus 10 percent line
voltage variation. When specified (see 6.2.1), overall line-voltage or
oscillator plate voltage regulation shall be provided. Regulation of plus
or minus 2 percent of rated voltage shall be maintained with a line voltage
variation of plus or minus 10 percent. If voltage regulation is not pro-
vided, filament and plate supply transformers shall be provided with taps
to be used for adjusting the voltage to the filaments of the rectifier
and oscillator tubes, and the plate voltage to the oscillator tube. The
transformer taps shall be in accordance with IEEE Standard No. 54.
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