b. Set OPR/TUNE switch to TUNE.
PWR switch to OFF for a minute before
repeating e below.
e. Immediately adjust the POWER AMPLIFIER TUNE
Do not allow the power amplifier to
control and then the POWER AMPLIFIER LOAD control
remain keyed for more than a few
to obtain maximum deflection on the XMTR OUTPUT
seconds at a time while tuning, since
meter. If the antenna being used has a length greater than
excessive dissipation tends to burn out
15 feet, check for crossover frequencies. A crossover
the vacuum tubes and serious damage
frequency is one where the antenna in use is too long to be
can result to components of the output
properly resonated at the operating frequency and is
readily detected by an increase in XMTR OUTPUT meter
c. Refer to figure 3-2 which is the same chart that is on
deflection as the POWER AMPLIFIER LOAD control is
the receiver-transmitter front panel. On POWER
rotated to 0.
AMPLIFIER LOAD and POWER AMPLIFIER TUNE
controls (fig. 3-3), loosen lock knobs. Adjust the turns
counters of the controls to the settings indicated on the
Proper output circuit resonance is
LOAD TUNE chart as follows. The outer scale of each
normally obtained without rotating the
turns counter is numbered in units from 0 to 39 and
POWER AMPLIFIER TUNE and
represents the whole-number part (coarse tuning) of the
POWER AMPLIFIER LOAD controls
turns count shown on the LOAD- chart (fig. 3-2). The
more than 3 turns from the initial
inner scale of each turns counter (fig. 3-3) is numbered
setting in c above.
from ~ to 100, and this scale makes 1 complete rotation
f. Again rotate the POWER AMPLIFIER LOAD and
per outer scale unit division. The inner scale represents
the POWER AMPLIFIER TUNE controls in either
the decimal part (fine tuning) of the turns count. For
direction to obtain a maximum indication on the XMTR
example, suppose it is desired to resonate the output
OUTPUT meter. Note maximum deflection value.
circuit to an operating frequency of 5.5 MHz and load a
Rotate POWER AMPLIFIER LOAD control
15-foot whip antenna. The proper initial setting for the
clockwise (increasing load) until the indication on the
outer scale TUNE control is indicated on the chart at the
XMTR OUTPUT meter drops one or two divisions.
intersection of the dashed lines marked TUNE with an
h. Readjust the POWER AMPLIFIER TUNE control in
imaginary line extending vertically from the 5.5-MHz
either direction to obtain a maximum deflection on the
frequency scale. This value is read on the left- scale
XMTR OUTPUT meter. Note the maximum value of
(KNOB TURNS) of the chart as 15 (approximately).
Similarly, the outer scale LOAD control setting is
i. If the maximum indication obtained is greater than
indicated on the chart at the intersection of the solid curve
the value in f above, repeat g and h above until the
marked 15 FT LOAD and the imaginary line extending
absolute maximum value is obtained. If the XMTR
vertically from the 5.5-MHz frequency scale. This value
OUTPUT meter indication of h above is less than the
is also read on the left-hand scale of the solid curve that
indication of f above, rotate the POWER AMPLIFIER
agrees with the length (15, 25, or 45 foot) of the antenna
LOAD control counterclockwise (decreasing load) until
being used, and adjust the outer scale turns count to
the deflection of XMTR OUTPUT meter decreases two or
provide the proper frequency of operation.
three divisions. Readjust the POWER AMPLIFIER
TUNE control in either direction for maximum deflection
on the XMTR OUTPUT meter. Repeat until absolute
Do not touch the antenna above the
maximum deflection is obtained.
threaded stud during transmission.
j. Set the XMTR PWR switch to HI and immediately
Serious injury or DEATH could result.
peak the XMTR OUTPUT meter deflection by fine
d. Set the XMTR PWR switch (fig. 3-1) to LO.
adjustments of the POWER AMPLIFIER LOAD and
POWER AMPLIFIER TUNE controls as indicated in f
Do not allow the XMTR OUTPUT
through i above.
meter needle to peg off-scale; always
k. Return XMTR PWR switch to OFF, and carefully
reduce the deflection slightly by
tighten the LOCK knob to secure the turns counters of the
adjusting the M ADJ control
POWER AMPLIFIER LOAD and POWER AMPLIFIER
deflection is not obtained, reset XMTR