Hammarlund HX-50 - Page 9

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Turn the "Operations" switch to Standby and
allow at least a one minute vacuum tube warm-up.
Turn the "Operations" switch to MaX and adjust
"Driver Tune" for maximum meter deflection. Then
adjust "Final Tune" for the highest reading. Repeat
adjustment of both Driver and Final Tune until Meter
deflection cannot be improved.
CW OPERATION
Turn the "RF Level" control until the "Level
Indicator" reaches a maximum (saturates). Use the
lowest setting of the control consistent with obtain-
ing maximum output (knee of curve). Adjust "Meter
Sensitivity" control to read "0" db.
Turn the "Function" switch to CW and key the
transmitter via the "Key" jack.
SIDEBAND OPERATION
After the transmitter ha s been tuned up to a de-
sired frequency on CW, adjust the "ALC" control
(on the rear of the chassis) so that the "Level Indi-
cator" drops to -1 db or one half a division. Turn
the "Function" switch to USB or LSB and the
"Audio Level" control knob until the "Level In-
dicator." meter fluctuates or averages around the -10
db marking when talking into the microphone at con-
versational level. This setting will usually be 4 to
5 depending on the mike, speaking level and distance.
VOX SENSITIVITY - VOX DElAY -
ANTI-TRIP OPERATION
After the transmitter has been tuned up to the
desired frequency with all of the larger sized knobs
adjusted, the VOX Relay control knobs are brought
into adjustment.
Turn the "Operations" switch to indicate VOX
and turn the "VOX Sensitivity" knob clockwise until
the VOX relay readily closes when talking into the
,microphone. It is desirable to keep the "VOX Sensi-
tivity" as low as possible since any undesired
background noise in the Ham Shack will trigger the
VOX relay and you will be on-the-air. Usually the
"VOX Sensitivity" knob will be near the center of
its range or pointer vertical.
The de-energizing time for the VOX Relay is
controlled by the "VOX Delay" control. This control
is used to keep the VOX Relay closed during the
quiet periods between words. Turn the "VOX Delay"
control clockwise until the relay flutter between
words is eliminated during the course of conversa-
tional speech. Excessive "VOX Delay" should be
avoided. Leave at CCW position to start.
The "Anti-Trip" Control is used when the "Oper-
ations" switch indicates VOX operation. When the
Page 8
Station receiver and speaker are connected for VOX
operation (see Figure 2) the speaker "Anti-Trip"
control is adjusted to a setting where the audio
'signa~ picked up by the microphone from the re-
ceiver's speaker will not energize the VOX Relay.
This feature prevents the retransmitting of the in-.
coming audio signals from your station receiver.
Excessive speaker volume is capable of disabling
the VOX Relay completely, therefore, minimum re-
quired gain should be used. Always adjust the
receiver audio gain to the desired level before ad-
justing the "Anti-Trip" control.
AM OPERATI,ON
Turn the "Frequency" and "Band Selector"
knobs to indicate anyone of the authorized amateur
phone bands. Tune the transmitter for maximum out-
put as outlined in the general and CW sections with
switches on DSB and MaX. Reduce the RF Output
level to indicate -6 db on the "Level Indicator".
Increase the audio level until there is a small fluc-
tuation or kick upward in the output level meter
pointer when talking into the microphone.
The carrier reference level can be established
more precisely if an oscilloscope and audio oscil-
lator are used to set up and monitor the output
signal. If the carrier level is set too high, peak
amplitudes are flattened before 100% modulation
occurs. If the carrier level is set too low the maxi-
mum power output capabilities are not attained at
100% modulation.
FSK OPERATION
FSK Operation is accomplished with the aid of V4
(l2BY7) Reactance Tube Modulator which shifts the
frequency of the 60 Kcs Carrier Oscillator by means
of a change in modulator screen voltage (see Figure
3). Lowering the screen voltage lowers the frequency
of the 60 Kcs Oscillator and raises the RF Output
Frequency; conversely, raising the screen voltage
raises the 60 Kcs Oscillator frequency and lowers
the RF Output Frequency. The change in screen
voltage is controlled by the Polar Relay keying
employed for RTTY.
The amount of Frequency Shift is adjusted by the
FSK Deviation control R140. When the Polar Relay
is closed the screen voltage on the Reactance Modu-
lator may be raised, lowered, or remain unchanged
depending on the position of the arm of FSK Devia-
tion Potentiometer. The zero position is located at
(approximately) the center of its range. Clockwise
rotation from the center position will decrease the
s cre en voltage and lower the frequenc y of the 60
Kcs Oscillator. Counterclo~kwise rotation from the
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