Tektronix Type 130, Instruction Manual

Page: 22 / 53

Calibration Procedure — Type 130
5-2
AA
Fig. 5.3. Left side view showing test points.
3. Multivibrator Duty Cycle, R68, ADJ. 1
Connect the Type S-30 Delta Standards to the UN-
KNOWN connector. Using the COARSE ZERO and Fine
ZERO controls, set the L-C Meter accurately to zero
indication with the S-30 at 0
μμ
f, and then switch both units
to 300
μμ
F.
Without making any other changes, turn the ADJ. 1 con-
trol hard right and measure the voltage at the
MULTIVIBRATOR DUTY CYCLE CHECK POINT (R74)
with a DC voltmeter (see Figure 5-3). Carefully note the
voltage reading, which should be around 155 volts.
Then, turn the ADJ. 1 control hard left and again
measure the voltage at the MULTIVIBRATOR DUTY
CYCLE CHECK POINT, and carefully note the reading,
which should be around 105 volts.
Turn the ADJ. 1 control back until the voltage rises to
midway between the two readings (i.e., around 130 volts).
This will indicate that the duty cycle is 50%.
4. Multivibrator Amplitude, R78, ADJ. 2
With S-30 set to 0
μμ
f, recheck that the L-C Meter
accurately reads zero.
Switch both units back to 300
μμ
f, and turn ADJ. 2 (see
Figure 5-4) so that the indicating meter reads 300
μμ
f.
5. LC Balance, T1 slug
Set the S-30 to SHORT CIRCUIT and the L-C Meter to
3
μ
h. Now carefully adjust the L-C Meter to zero with the
front panel controls.
Switch the S-30 to 300
μ
h and the L-C Meter to the 300
μ
h range. Carefully read the amount of error. Leaving all
other controls as they are, adjust the tuning slug in T1 to
increase the amount of error by a factor of three.
Repeat steps 4 and 5 until the L-C Meter reads both 300
μμ
f and 300
μ
H without error.
Fig. 5.4. Right side view showing calibration control points.
6. Resistance Compensator, C7
With the S-30 at 0
μμ
f, set the L-C Meter ZERO controls
to get about a half-scale reading on the 10
μμ
f range. Set
teh S-30 to 1 megohm and adjust the ZERO control so the
meter deflection indicates an even scale division. Switch
the S-30 to 100 kilohm and see if there is any change in
teh deflection. If there is a change, adjust the RESIST.
COMP. Control, (see Figure 5-3), so the deflection is the
same as for the 1-megohm position and repeat a time or
two.
If you cannot find a satisfactory adjustment, try a new
tube for V4, and try the procedure again. Tubes that
cannot be compensated by adjustment of C7 will drift in
frequency when the line voltage changes.
7. 0-3 Range, ADJ. 3, R100
Set the S-30 to 0
μμ
f and the L-C Meter to 3
μμ
f. Care-
fully set the FINE ZERO control for zero deflection.
Then set the S-30 to +3
μμ
f and set the ADJ. 3 pot,
R100, (see Figure 5-4), so that the indicating meter reads
accurately at full scale.
Now set the S-30 to
–3 μμ
f and check to see if the meter
still reads full scale. If not, adjust the FINE ZERO so meter
is at full scale.
Reset the S-30 to +3
μμ
f and reset ADJ. 3 if necessary
for full scale reading.
This procedure minimizes a small error in zero setting
that may occur in the case that the zero is off due to lock in
of the two oscillators.
8. 0-10 Range, ADJ. 4, R99
Set the S-30 to 10
μμ
f and the L-C Meter to 10
μμ
f. Set
the ADJ. 4 control so that the indicating meter reads full
scale.