HP 61 Application Note

APPLICATION NOTE
LEVELED SWEPT-FREQUENCY MEASUREMENTS WITH OSCILLOSCOPE DISPLAY
Oscilloscope graticule scales furnished with this
Application Note permit calibrated reflection and
transmission measurements over broad frequency
bands using % 690 series leveled sweep oscillators.
You can now use an oscilloscope to provide a cali-
brated, immediate, and continuous display - with-
frequency of transmission-loss or SWR, so that
accurate on -the - spot adjustments to equipment can
be made.
This Application Note shows how oscilloscope/sweep
oscillator displays are set up. Full-size calibration
scales for both transmission and reflection measure-
ments are included. Crude grease-pencil calibration
lines for the oscilloscope face or preliminary cali-
bration plots made with a ratio meter and an X-Y re-
corder are no longer required.
Sweep oscillators and associated instruments are
available for testing both coaxial and waveguide
microwave components from 1 to 40 Ge. Such items
as adapters, impedance transformers, tuners, loads,
filters, detectors, couplers, and attenuators can be
measured or adjusted. Swept-leveled techniques are
also useful for overall system analysis.
Leveled sweep oscillators are not only helpful design
aids, but can be used as maintenance tools as well.
They will serve for fast routine maintenance checks
on laboratory instruments. Figure 1A, for example,
shows a reflection imperfection on an intermittently
defective 2200-Mc low-pass filter. It was quickly de-
tected and repaired after using leveled sweep -fre-
quency techniques. Figure 1B,gives the reflection
COMPLETE COVERAGE IN
characteristics of the repaired filter. The filter de-
fect (a faulty type "N" connector) could have gone
unnoticed using point-by-point measurements. Hours,
and sometimes days, of tedious precise measurements
can often be completed within minutes.
Figure 1A. Reflection
from 2200-Mc Low-
Pass Filter. Peak at
2900 Mc is from
defective type N
connector.
3
Frequency in Ge
Figure 1B. Reflection
from 2200-Mc Low-
Pass Filter shown x
in 1A, after repair of %
defective connector.
3
Frequency in Gc
TRANSMISSION MEASUREMENTS
Typical setups for making coaxial and waveguide
transmission measurements are shown in Figures 2,
3, and 4. The forward-wave detected signal is ap-
plied to the sweep oscillator for leveling purposes.
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ELECTRONIC MEASURING EQUIPMENT