Tune Oscillator And Amplifier - HPE 606A Operating And Servicing Manual

Model 606A
4) Measure the ripple voltage on the various
supplies. They should approximate the values in-
dicated in Table 4-5 with the power line voltage
set at 115/230 volts.
REGULATED POWER
SUPPLY TOLERANCES
TABLE 4-5.
Output
Voltage
Range
Nominal
Voltage
Nominal Ripple
at 115/230 vrms
Input
~200 200
(violet wire) +8 volts
+300 300
(red wire) +12 volts
+27
(brown-orange
wire)
unregulated
4-12 AUDIO OSCILLATOR
Set RANGE ------- _* - 540 KC-1800 KC
MODULATION SELECTOR - - - - INT 400%
1) Turn POWER switch to ON.
2) Connect an ¢) 400D AC VTVM to output tap on
audio transformer (yellow lead on single tie point
behind rf output meter), Connect ground lead of
voltmeter to ground,
3) Set Mod. Osc. Adj (R51) potentiometer for 3.2
volts. This control is the middle one in the row of
five potentiometers on top of the modulation deck,
4-13 CRYSTAL CALIBRATOR
Set XTAL CALIBRATOR - - - - ---- 100 KC
1) Connect an electronic counter to pin 2 of the
Crystal Oscillator tube (V10).
2) Adjust trimmer (C41) for exactly 100.000 KC.
This trimmer is the ceramic capacitor on the right
side (as viewed from the front) of the instrument
under the modulation deck.
3) Set XTAL CALIBRATOR to 1 MC and read
counter. Reading should be between 999.900 to
1000.100 KC,
Sect. IV Page 13
4) Set XTAL CALIBRATOR to 100 KC and read
counter, Reading should be between 99.990 to
100.010 KC,
5) Set trimmer C41 to best compromise between
the above limits.
6) Turn XTAL CALIBRATOR to OFF.
4-14 TUNE OSCILLATOR AND AMPLIFIER
NOTE
This procedure should be performed only if there
is a definite indication that the oscillator is off
frequency. It should NOT be done ona routine basis.
Set CALIBRATE cursor to align with FREQUENCY
centerline
ATTENUATOR - - -------- .3 VOLT
MODULATION SELECTOR - - - - - - = CW
FREQUENCY dial - - - - - low end of one
of the bands(except highest frequency)
1) Connect RF OUT terminal to an electronic
counter, such as the @ Model 524B/C/D with a
Model 525A Converter.
2) If the frequency as read on the FREQUENCY
dial is off more than 1%, adjust the slug inthe
oscillator coil to correct. This slugcanbe reached
by removing the cabinet (see paragraph 4-2) and
removing the plug button in the rf shield (on left
side of instrument when viewed from the front).
Rotate the turret to put the coil in position so that
the tuning screw can be reached. Afteradjustment
rotate the turret to put the coil back in operation
to recheck, Clockwise rotation of the slug vill
decrease the frequency.
3) Shift the frequency to the high end of the band.
If the frequency as read on the FREQUENCY (ial
is off more than 1% adjust the trimmer capacitor
(C7) across the oscillator coil to correct. This
adjustment can be made through the same hole in
the rf shield as in step 2 without having to move
the turret. Always use a plastic screwdriver wen
making this adjustment.
4) Repeat steps 2 and 3 until no further adjustment
is necessary.