(Equal to or better than)
(Refer to equipment list)
Every 10 MHz
Every 100 MHz
Every 500 MHz
Every 1.0 GHz
Sensitivity is specified at the mixer input. Insertion loss through the cable, at the higher (GHz) frequency range, will become significant. Fig.
is a graph that shows
the approximate loss
in dB for
a 6 foot
When checking the sensitivity of scales 7 and 8, apply the source signal to the Waveguide Mixer, then connect the Waveguide Mixer to the
Mixer Adapter-through the 2 foot cable with TNC connectors.
d. Check the dial accuracy as follows:
2) Center the FINE RF CENTER FREQ control. Depress the
LOCK CHECK button and adjust the RF CENTER FREQ con-
1) Tune the RF CENTER FREQUENCY through the band.
trol until a beat frequency is displayed.
Observe the 100 MHz harmonics and their image spurii as
they travel across the screen towards the center and merge
3) Adjust the FINE RF CENTER FREQ control for a lock
with the IF feedthrough response, as the dial crosses a fre-
condition or until the beat reduces to zero (zero beat).
quency check point. The harmonics then separate and move
4) Repeat the above procedure with a 5 MHz signal from
off the screen. See Fig. 6-47. Maximum error between the
dial readings and frequency check points must not exceed
5) Increase the input signal amplitude to 5 V peak to
(2 MHz + 1% of the dial reading).
peak and repeat the check with the increased signal ampli-
2) Adjust the MIXER PEAKING control to optimize signal
tude at 5 MHz and 1 MHz.
amplitude. Note the spectral display of the harmonic genera-
tor signals. Tune the RF CENTER FREQUENCY through the
38B. Alternate Procedure to Check Dial Accur-
band, checking for dead spots which could be caused by
acy, Oscillator Mixer `Operation and Ef-
either local oscillator failure or mixer malfunction. The MIXER
PEAKING must be peaked at all check points.
e. Check-Local oscillator phase lock operation as follows:
a. Equipment setup is shown in Fig. 6-46.
1) Turn the INT REF FREQ control on. Decrease the DIS-
b. Apply 100 MHz (10 ns) markers from the marker output
PERSION to 500 kHz/div.
2) Depress the LOCK CHECK button and adjust the FINE
the 200 MHz trap, and the 20 dB attenuator to the band B
RF CENTER FREQ control to position the display to the center
RF INPUT connector.
of the graticule area. Release the LOCK CHECK button.
c. Switch the band selector to B. Set the DISPERSION to
3) Shift the IF feedthrough response approximately 2
2 MHz/div and switch the VERTICAL DISPLAY selector to
divisions off center with the IF CENTER FREQ control, then