Hallicrafters SR-150, Operation And Maintenance Manual

By Walter Cates WD0GOF (UPDATE 10/30/2013)  

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SR-150 REFURBISHING AND REPAIRING CONTINUED:  

When you clear the fault return to this point in the process. If you got the peak in the plate current, key the 

transmitter again, adjust the FINAL TUNING for a dip in plate current. As the dip occurs you should get an 
increase in power output. If you get no dip or if the power peak and current dip do not coincide it means the PA 
needs to be neutralized. We won’t worry about neutralization at this point. 

Keep the transmitter duty cycle as 

short as possible at all times.

 Observe the preselector setting. The pointer of the PRESELECTOR control 

should be in the center of the 40 meter bar. If not move the pointer to the center of the bar, key the transmitter 
and peak L10 and L40 for max power out. Key the transmitter and re-peak the PRESELECTOR and the PLATE 
TUNING. Key the transmitter and momentarily advance the RF LEVEL to max while observing the wattmeter 
you should get between 40 and 100 watts. Recheck the location of the PRESELECTOR pointer and repeat as 
necessary to get it centered. At this point you have proven 80% of the transmitter circuitry. Now check the rest 
of the bands. You will need to adjust the driver grid and plate coils on each band. Set the PRESELECTOR 
pointer to the center of the band segment and the main tuning to 250 on the black scale. L11, L41 – 80 meters  

L9, L39 – 20 meters  
L8, L38 – 15 meters  
L7, L37 – 10 meters (you will only test the 28.5 band at this time; most rigs don’t have the other xtals anyway.)  

Do not worry about low power at this time. If you can get 40 watts or better you are good at this point. If you 

have a band that doesn’t function then the fault most likely is in the band switch, the driver grid or plate coils or 
plate loading ckt. Those faults must be cleared before you proceed. You are now ready to neutralize the PA and 
perform the overall alignment. A precise neutralization procedure can be found in the SUBSYSTEM  

TECHNICAL INFORMATION section of this document. There are still a few ckts you have not proven. A full 

alignment will proof the rest of the system. Go to Section 8 of your Hallicrafters INSTALLATION AND 
OPERATING INSTRUCTIONS manual for the complete alignment procedure. You may check but need not 
perform the procedures in subsections 8-3, 8-10, 8-12, 8-14, 8-16 and 8-17. These steps are complete now. You 
will find the setup for VOX in section 5 of the Hallicrafters manual. The RECEIVER and TRANSMITTER 
performance data sheets In the DATA SHEETS section contain the minimum performance standards for the 
unit.  

1-9-3. TX DRIVE FAULT ISOLATION  

The receiver works well but there is no transmitter power out. If the receiver does not work you must make it 

work first, go to RECEIVER FAULT ISOLATION.  

We will start at V7 the transmitter mixer.   
Set the STANDARD PRE-POWER UP CONFIGURATION. Set the main tuning to the black scale 400. Select 

the 40 meter band. Connect the X10 scope probe to Pin 1 of V7. Remove V9 from its socket. Power up and set 
the OPERATION switch to MOX. Allow 5 minutes warm up then key the transmitter. You should see a signal 
of approximately 3 Vpp on the scope. Move the scope probe to the frequency counter. The counter should read 
13.5 MHz. If the signal is not there or not close to the proper frequency you have a problem in the HET osc or 
the CR2 switching circuitry.  
  

If the signal is correct unkey, power down, replace V9 and pull V8. Power up, warm up, move the scope probe 

to the scope and key the transmitter. You should see a signal of approximately 5 Vpp on the scope. Move the 
probe to the frequency counter, it should read very near 6.1 MHz.