REPAIR AND RESTORATION OF THE SR-2000
14
WDØGOF 3/7/20014
3-3. INITIAL SETUP TESTS
3-3-1 S-METER ZERO ADJUSTMENT
Re check meter zero. If it has drifted return to section 2-6 and reset adjustment.
3-3-2 BIAS ADJUST
Go to the manual and complete the procedure in section 8-3. If you are unable to set the proper plate current go
to section 5-5-1.
3-3-3 TRANSMITTER PRETEST
Go to the manual and complete the procedure in section 8-5. If you are unable to null the carrier to a level of
60db below the maximum output level of either side band you have a fault that must be corrected before
proceeding (section 5-1). Perform the procedures in the manual section 5-4 through 5-7.
If the equipment functions per the instructions no further diagnostics is required and you are ready to start the
alignment procedure in section VIII in the factory manual. If not proceed to initial transmitter tests section 3-4
of this document.
3-4 INITIAL TRANSMITTER TESTS
The next series of tests will be conducted in the MOX, TUNE mode. You will need to switch the FUNCTION
switch from LSB to TUNE quite often. You MUST keep the transmit duty cycle short.
I find it easier to plug a
key into the key jack on the rear of the transceiver. Then you can set the FUNCTION switch to the CW
position and leave it there and press the key when you want drive. This saves wear and tear on the
FUNCTION switch and reduces the chances of leaving the transmitter keyed to long
. For the remainder of
the tests when you are instructed to “
key the transmitter
” you will either switch the FUNCTION switch from
LSB to TUNE or press the key.
Preset all controls as stated in section 3-2
3-4-1 TRANSMITTER DRIVE TEST PROBE PICK UP
For the drive tests you will need to construct a capacitive pick up collar. This collar is nothing more than a
snuggly fitting metal tube placed over the driver tube in place of the tube shield. This collar will get hot enough
to melt your scope probe. That is why the long buss wire was used. I constructed one from an old snug fitting
tube shield. I cut off the bottom so the shield would not contact ground. I then bent a buss wire into a loop with
a pigtail. I used the tabs that formally held the spring in place to anchor the buss wire in place. The signal levels
in this document were determined with the pick-up probe I constructed. The levels are dependent on the size
and fit of the pick-up. Some difference can be expected to occur with different construction methods. Norms for
your pick-up will need to be determined on a working system.
