MFJ-216 Instruction Manual Deluxe Amplifier Saver
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The CARRIER button is a momentary contact switch that temporarily locks the
transmitter in a continuous carrier transmit mode.
The PULSE button is a latching switch that activates the pulse circuit when
pressed in and locked.
Speech Duty Cycle
The duty cycle of average power to peak envelope power varies widely in the
real world. Every voice and system varies, no universal duty cycle of peak to
average power applies to the many real-world combinations of voices and
equipment.
Unprocessed speech usually has an average power between one percent and ten
percent of peak envelope power. Sustained speech, such as a long "hello",
produces average power levels that typically range from 10 to 30% of PEP.
Heavy speech processing increases the average power, pushing the short term
average power of normal speech to 30% or more.
During normal voice operation, most equipment heat is generated by the
quiescent current required to make the transmitting system linear. Proper
amplifier or transmitter tuning require adjustments at maximum peak power,
generally with maximum available drive from the exciter. A continuous tone or
carrier is generally used during adjustment, and the amplifier is generally tuned
for maximum output.
The continuous single tone carrier, commonly used to adjust the PA or tuner,
will raise heat significantly. The MFJ-216 Deluxe Amplifier Saver allows proper
tuning while driving the PA with a low duty cycle wave form. It is NOT
necessary to use a peak reading meter when adjusting an amplifier or tuner with
the MFJ-216 Deluxe Amplifier Saver, although the lack of a true peak reading
meter will prevent you from knowing the amount of peak power produced.
PULSE RATE and DUTY CYCLE
The MFJ-216 has two front panel controls labeled Pulse rate and duty cycle. As
indicated by the names, these controls adjust the rate at which the transmit
keying pulses occur (pulse rate), and the ratio of on- to-off time (duty cycle).
Some care must be used to insure PULSE RATE is slow enough, and the DUTY
CYCLE is long enough, to be within the keying response limits of the exciter
