7
1-4, INITIAL POWER UP
First and of critical importance, you must have a power supply that has been tested and meets all the original
specifications. NOTE: The actual B+, high voltage and negative bias voltages measured in your system will
vary from the values on the schematic and in this document
.
The AC input voltage must be from 105 to
125vac
. A 5v change in the AC voltage will equate to about a 20vdc difference in the high voltage, 10vdc in the
B+ and about 5vdc change in the bias voltage. The voltages measurements in this document relate to 122vac
bench supply. You will need a dedicated voltmeter plugged into the test jacks in the rear of the PS-150 to
monitor plate current. It will remain there throughout all testing. It will need 2.5v full scale and 5 or 10v full
scale switch positions. Remove the top and bottom covers of the HT-44. Remove the case.
BE AWARE, from this moment on you are exposed to LETHAL HIGH VOLTAGE.
Unless otherwise noted the
turn on preset conditions
will be:
•
VFO SELECTOR ------------------- XMTR
•
MIC GAIN --------------------------- Ø
•
RF LEVEL --------------------------- Ø
•
FINAL TUNING -------------------- center of 40-meter bar.
•
DRIVER TUNING ------------------ center of 40-meter bar.
•
BAND SELECTOR ----------------- 7.0
•
VFO DIAL --------------------------- 230
•
FUNCTION -------------------------- AM
•
OPERATION ------------------------ OFF
•
DELAY ------------------------------- full counterclockwise
•
CAL LEVEL ------------------------- full counterclockwise
•
CAL RESET ------------------------- center of its rotation
•
NORM/XCVE (slide switch on rear of chassis) ---- NORM
•
ANTENNA -------------------------- connected to wattmeter/dummy load
NOTE: Throughout all testing when powered up, OPERATION in MOX position and FUNCTION in the AM
position is the “safe” mode. There should not be any plate current in the PA final tubes. Any time you are not
performing a specific test the equipment should be in the “safe” mode.
Before turn on:
Locate and become familiar with the following, R124, 5k 10w, pin 11 of S1 (VFO SELECTOR should be a
solid white wire). Remove the PA cover.
CAUTION YOU WILL BE EXPOSED TO LETHAL VOLTAGES.
OBSERVE THE FREE HAND RULE, THAT IS FREE HAND IN HIP
POCKET WHILE TAKING MEASUREMENTS. YOU COULD DIE
.
NOTE:
The PS-150 power supply voltages normally run much higher than original documents and schematics
indicate. I suspect this was true when the radios were new. A clue can be found on the voltage chart figure 12
in the original factory manual. You will note the screen voltage with the PA tubes cut-off was charted as
285vdc. That would have been with the AC input at 117vac. My bench power runs 123vac. The nominal
voltages for the PS-150-120 power supply on my bench are: The +250vdc runs +305vdc. The -125vdc runs -
150vdc. The +575vdc runs 680vdc. The +150vdc should be /- 2vdc. Throughout this document I will
use the values as documented in the original manual.