24
2-2-5 AALC
When a small amount of grid current occurs in the final amplifier, an audio signal appears on the bias line in proportion
to the amount of grid current. This audio component is coupled to the AALC circuits for processing. The resulting DC
voltage is fed as a gain control to V7, the 6Meg I.F. amp. The actual amount of AALC action varies from rig to rig. It is
dependent upon the condition of the PA final tube, the gain of the second mixer and driver and the voltages from the
power supply. If the AALC does not function check V7 and CR1 and CR2.
2-2-6, DRIVER TUNING SETPOINTS
Why worry about it? The mismatch of L and C in the circuit will
eventually lead to oscillations in the driver or harmonics and
spurs in the transmitter. Before we start insure the knob is
indexed correctly. Turn the knob until it hits the stop in
counter clockwise direction and note the position of the
pointer. Now reverse the direction to the stop and note the
pointer position. If the two end points are not balanced from
end to end you will need to loosen the set screws in the outer
shaft couplings and position them properly. Watch the shaft
and turn the knob from end to make sure you know what is
going on before trying to make any adjustments. Read
through the process before you start.
NOTE: This same error will occur with the FINAL TUNING control. It is usually caused when L28 has been deformed by high VSWR heating. Getting
the tuning back to where it should be usually requires a new L28 and optimizing C100, 101, 102, 103 and 104.
We will start with the 40 meter band.
•
Band switch to 7.0. VFO to 230. DRIVER TUNING to center of 40 tab.
•
In CW with telegraph key installed key up.
•
Adjust FINAL TUNING for max power output.
•
If there is no power output, you will have to tune and walk the control back to where it belongs.
•
Adjust the DRIVER TUNING until you find the power peak.
•
Peak the driver and final for max power. Using the RF LEVEL keep the power around 75 to 100 watts.
•
Move the DRIVER TUNING knob slightly in the direction to the position where it should be maintaining at least 20
watts output.
•
Adjust C39C, L8 and L18 for max power.
•
Move the DRIVER TUNING again in the proper direction and readjust C39C, L8 and L18.
•
Repeat until you have walked the DRIVER TUNING control back to where it should be.
You will repeat this procedure on the remaining bands
.
BUT
, YOU WILL
NOT
RE-ADJUST C39C
•
On 80 meters set the VFO to 900 adjust L9 and L19
•
On 20 meters set the VFO to 280 adjust L7 and L17
•
On 15 meters set the VFO to 360 adjust L6 and L16
•
On 10 meters band switch to 28.5, set the VFO to 750 adjust L5 and L15
Go to 1-8 and revisit the 10 through 80meter driver/PA alignment.