TB 9-6625-2055-24
IDENTIFICATION AND DESCRIPTION
1. Test Instrument Identification.
This bulletin provides instructions for the
calibration of Delaying Time Base, Tektronix Type 7B85. The manufacturer's manual was
used as the prime data source in compiling these instructions. The equipment being
calibrated will be referred to as the TI (test instrument) throughout this bulletin.
a. Model Variations. Variations are explained in text where serial numbers differ.
b. Time and Technique. The time required for this calibration is approximately 4
hours, using the dc and low frequency technique.
2. Forms, Records, and Reports
a. Forms, records, and reports required for calibration personnel at all levels are
prescribed by TB 750-25.
b. Adjustments to be reported are designated (R) at the end of the sentence in which
they appear. When adjustments are in tables, the (R) follows the designated adjustment.
Report only those adjustments made and designated with (R).
3. Calibration Description. TI parameters and performance specifications which
pertain to this calibration are listed in table 1.
Table 1. Calibration Description
Test instrument parameters
Performance specifications
Sweep rates
Calibrated range: 5 s to 10 ns/div in 27 steps, X10 magnifier
extends fastest calibrated sweep to 1 ns/div
Mag
Accuracy: (over center 8 div):
Unmag
5%
5 to 1 s/div
4%
0.5 s to 0.1 s/div
2.5%
1.5%
4%
2.5%
50 to 10 ns/div
Mag registration
0.5 div or less from graticule center when changing from MAG X
10 to MAG X 1
0.0 to at least 9.0 times TIME/DIV switch setting
Variable time delay
Range:
Accuracy: 0.5 s/div to 50 ms/div; Within (0.5% measurement
+0.1% FS +1 least significant digit)1
20 ms/div to 100 ns/div; Within (0.5% measurement
+0.03% FS +1 least significant digit)1
Delay time
Range:
0.2 or less to at least 9.0 times TIME/DIV switch
setting
Accuracy: Start of delayed sweep display (with respect to start of
delaying sweep display) 0.5 s/div to 10 s/div.
Within (0.5% measurement +0.5% FS)1
1Full
scale equals 10 X the TIME/DIV switch setting.
