TB 9-6625-2212-24
11. Harmonic Loss
a. Performance Check
NOTE
To ensure accurate notch depth and shape when checking total
calibration fixture OUTPUT connector must be at least 1 M .
In addition, the load capacitance (instrument connected to the
output) and coaxial cable capacitance must be <75 pF. An 18
inch, 50
coaxial cable has a capacitance of 45 pF; therefore,
keep all cables as short as possible.
(1) Connect function generator Function Output Unbalanced to TI INPUT.
(2) Connect TI OUTPUT to true rms voltmeter INPUT.
(3) Position true rms voltmeter controls as listed in (a) through (d) below:
All front panel pushbuttons released to out position, except POWER.
(a)
DISPLAY dB/VOLTS pushbutton pressed to dB.
(b)
DISPLAY REL/dBm pushbutton released to dBm.
(c)
dBm REFERENCE [ ] switch to 600.
(d)
(4) Position controls as listed in (a) through (d) below:
NOTCH FREQUENCY switch to 100 kHz.
(a)
ADJUST FOR NULL controls for center position.
(b)
MODE pushbutton to FLAT.
(c)
ATTEN pushbutton to 0 dB.
(d)
u
(5) Set function generator for a sine wave, 0 dBm, 100 kHz, 600
nbalanced output.
(6) Press TI MODE pushbutton to NOTCH.
(7) Adjust ADJUST FOR NULL controls for a minimum indication on true rms
(8) Set TI MODE pushbutton to FLAT.
(10) Press true rms voltmeter DISPLAY REL/dBm pushbutton to REL.
(11) Press TI MODE pushbutton to NOTCH.
(12) Reverse dBm sign (- becomes +) and record true rms voltmeter indication as
second harmonic loss on test report provided in appendix A.
(13) Set TI MODE pushbutton to FLAT.
(14) Release true rms voltmeter DISPLAY REL/dBm pushbutton to dBm.
(15) Repeat technique of (9) through (14) above for three, four, and five times the
center frequency set in (5) above.