c. Turn the SIDEBAND switch to its counter-
clockwise position.
d. Turn the Mode switch to X-CW.
e. Adjust the Power Supply (AC-4 or DC-4) bias
control for a reading of 0.1 Amperes on the
plate current meter.
3-7. TUNE UP. Do not allow plate current to ex-
ceed 0.1 Amperes for more than 6 seconds with the
PLATE control not tuned for minimum plate cur-
rent or maximum RF output.
CAUTION
Failure to observe the warning above will
result in rapid final amplifier tube deteri-
oration due to excessive plate dissipation.
The final amplifier pi-network will match a nominal
50 ohm lead. The VSWR may be as high as 2: 1 on
all bands except 80 meters where a lower VSWR
may be required. On 80 meters an external antenna
matching network may be required.
Preset the controls as follows:
a.
b.
C.
d.
e.
f.
g.
Select the desired band with the BAND switch.
Select the desired operating frequency with the
VFO tuning knob.
Rotate the XMTR GAIN control full counter-
clockwise.
Rotate the LOAD control full counterclockwise.
Place the SIDEBAND control in the X position.
Place the Mode switch in the SSB position.
Peak the RF TUNE control for maximum noise
or signal as indicated by the S meter.
Rotate the Mode switch to the X-CW position and
advance the XMTR GAIN control until the plate
current meter moves up scale slightly. Peak the RF
TUNE control for maximum plate current and
quickly tune the PLATE control for a dip in plate
current. After the dip is found, rotate the XMTR
GAIN control clockwise until plate current no
longer increases.
Depress the LOAD control and alternately adjust
the PLATE and LOAD controls in small increments
for maximum RF output. Release the LOAD con-
trol and adjust the PLATE control for minimum
plate current. At this point the plate meter should
indicate a plate current between 0.380 and 0.500
Amperes. The reading will depend on the line volt-
age, antenna match, tube condition, etc. Increasing
the setting of the LOAD control beyond the point
at which maximum RF output occurs will result in
excessive plate dissipation. It should not be neces-
sary to advance the LOAD control beyond 4.5 to
obtain maximum RF output. Further advancement
indicates that the VSWR of the antenna system is
too high and leaving the control set beyond this
point is likely to result in excessive harmonic radia-
tion. The above procedure should be completed as
quickly as possible and the Mode switch should be
returned to the SSB position.
When the Mode switch is in the X-CW position, the
screen voltage on the final amplifier tubes is reduced
to prevent overheating. When the switch is in the
SSB position, this voltage is increased so that an
input power of 300 watts can ‘be obtained.
3-8. SSB
OPERATION.
In the following discussion, it is assumed that the
TR-4C has already been tuned up on the desired
band as described in paragraph 3-7. Preset the
controls as follows:
SIDEBAND -On desired sideband as
shown by indicator lights.
Mode -On SSB.
XMTR GAIN -Fully counterclockwise.
RF gain (lever) -Fully clockwise.
RCVR GAIN (knob) -Fully counterclockwise
(do not turn off power).
VOX gain -Fully clockwise.
ANTIVOX -Fully counterclockwise.
While talking into the microphone in a normal
voice, increase the XMTR GAIN control until the
S meter starts kicking up scale above its resting
value. With no modulation, the S meter will rest up
scale on transmit. This indicates that the transmit-
ter AGC is starting to operate and the transmitter
has maximum output. Continue talking and reduce
the VOX gain until a point is reached where further
reduction results in a too frequent relay drop out.
Increase the AF GAIN until received signals are of
the desired level. This may cause the transceiver to
cycle back and forth between transmit and receive.
Adjust the ANTIVOX control until the cycling
stops. If the push-to-talk switch on the microphone
is properly connected as described under Installa-
3 - 5
