D)Transmit Tuning And Operation; D.1.Initial Transmit Tune-Up - Heathkit SB-10 Series Troubleshooting Manual

d) Transmit Tuning and Operation
d.1. Initial Transmit Tune-Up
The steps of this procedure must be performed for all modes of operation.
Set the BAND switch and Main Tuning dial for the desired frequency.
Place the METER switch in the PLATE position.
Turn the MIC/CW LEVEL control fully counterclockwise.
With the RF load connected to the ANTENNA jack, set the MODE switch to TUNE. The meter
should read 50 mA (at the • mark on the HW-101). If the meter needle indicates other than 50
mA, perform the BIAS adjustment.
CAUTION: Do not turn on full output power continuously for more than 30 seconds at one time,
or the final amplifier tubes or power supply may be damaged. Each time full output power is
turned off, allow the tubes to cool for at least a minute.
Set the METER switch to PLATE and adjust the LOAD lever to the three o'clock position.
Set the FINAL TUNE knob to the position corresponding to the band in use.
Turn the MIC/CW LEVEL control clockwise to obtain a small up-scale indication on the meter.
Adjust the PRESELECTOR for maximum PLATE current
Adjust the FINAL TUNE knob to "dip" the PLATE current
While doing these adjustments, you may turn the MIC/CW LEVEL control clockwise slightly if
necessary to provide a measurable PLATE current
Perform the following step for the appropriate model.
SB Series: Set the METER switch to the GRID position. Turn the MIC/CW LEVEL control
clockwise until the meter just barely begins to show GRID current.
HW Series: Slowly turn the MIC/CW LEVEL control clockwise until the meter reading no longer
increases with knob rotation. Do not increase the MIC/CW LEVEL beyond this point.
Repeat the following two steps until the correct PLATE current is obtained
Adjust the FINAL TUNE knob to "dip" the PLATE current
Move the LOAD control clockwise to increase the amount of plate current at the "dip". The meter
needle should read approximately 40 on the scale (HW-101), or a plate current of 225-250 mA
(SB series).
Important: Before you put the transmitter into operation for the first time, and any time
you change the final amplifier tubes, make the following check: Tune the transmitter as
Transmit Tuning and Operation revised 12/17/2021 Page 28