MFJ-216 Instruction Manual Deluxe Amplifier Saver
4
The MFJ-216 Deluxe Amplifier Saver connects to the CW Key jack of your
exciter via the rear panel jack labeled "Output". The Output jack is a standard
RCA phono plug, with the center pin connected to the positive voltage keying
line (less than 50 volts and 100 mA) and the outer shell grounded. If the case
of the MFJ-216 Deluxe Amplifier Saver is kept isolated from ground, the MFJ-
216 Deluxe Amplifier Saver can be used with negative keying line voltage radios
provided radio keying line voltages are below 25 volts
. The primary concern is
the shock hazard and potential of accidentally keying the rig if the cabinet of the
MFJ-216 Deluxe Amplifier Saver or the operator comes in contact with
grounded equipment.
WARNING: Never use the MFJ-216 with negative keying line rigs
that have over 25 volts on the key jack.
Tuning Amplifiers
Nearly all power amplifiers (PA's) are properly tuned when maximum envelope
power is obtained with full exciter output. Tuning the amplifier to match exciter
peak power prevents gain compression (flat-topping), reduces splatter and
distortion, and reduces the chance of PA damage from arcing.
Maximum average power is directly related to (although considerably less than)
maximum peak power. While the lack of a good peak reading meter prevents
measurement of true peak power, virtually any RF power meter will provide a
correct indication of tuning. When the amplifier is tuned to produce maximum
average power when driven with a constant rate and duty cycle pulse, it is almost
certainly tuned for maximum peak power.
The least damaging and cleanest PA tuning condition generally occurs when the
PA is peaked slightly beyond maximum output, in a direction that OPENS or
UNMESHES the loading capacitor (this capacitor is sometimes called LOAD,
ANTENNA, COUPLING, or MATCHING).
Caution: Be very careful to avoid applying full drive power to the PA
without having the load control open far enough. When power
amplifiers are under coupled, tank voltages can be extremely high.
This may cause tank components, such as the band switch or
tuning capacitor, to arc and fail. It also stresses the tube and other
components with needlessly high voltages.
The MFJ-216 Deluxe
Amplifier Saver will NOT prevent voltage damage to components.
Adjust the two front panel controls to a 10 o'clock position. With the amplifier
in stand-by, push the Carrier Tune button and adjust the transceiver's power
control to the rated drive power of the amplifier. Place the amplifier into operate
