Suggested
Frequency
Band
Sensitivity
Signal Generator
(Equal to or better than)
Dial Accuracy
100 kHz
(Refer to equipment list)
1 kHz
Check Frequency
Hewlett-Packard
10 MHz
140
1
Model 608D
-80 dBm
-100 dBm
Every 10 MHz
275
275
2
400
-90 dBm
-110 dBm
Every 100 MHz
Hewlett-Packard
900
Model 612A
850
1.5 GHz
Hewlett-Packard
3
-85 dBm
-105 dBm
Every 500 MHz
Model 8614A
2.0
1.5
41
Hewlett-Packard
2.5
-90 dBm
-110 dBm
Every 1.0 GHz
Model 8616A
4.0
4.0
51
Polarad
6.0
-100 dBm
-80 dBm
Type 1107
8.0
Polarad
8.0
61
Type 1108
10.0
-75 dBm
-95 dBm
12.0
Hewlett-Packard
Model 626A
12.4
-90 dBm
72
15.0
-70 dBm
Hewlett-Packard
18.0
Model 628A
18.0
82
Hewlett-Packard
25.0
-60 dBm
-80 dBm
Model 938
26.5
Hewlett-Packard
82
-70 dBm
-50 dBm
Model 940
40.0
1
Sensitivity is specified at the mixer input. Insertion loss through the cable, at the higher (GHz) frequency range, will become significant. Fig.
2
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
the signal generator.
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
fectiveness of Local Oscillator Phase Lock
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
LOG.
6-43
