Sensitivity (50 W source)
Suggested Signal
Equal to or better than
Dial Accuracy
Frequency
Band
100 kHz
1 kHz
Check Frequency
(Refer to equipment list)
Hewlett-Packard
10 MHz
1
140
Model 608D
-100 dBm
-80 dBm
Every 10 MHz
275
275
400
-110 dBm
2
Every 100 MHz
-90 dBm
900
Hewlett-Packard
Model 612A
850
1.5 GHz
3
-105 dBm
Hewlett-Packard
-85 dBm
Every 500 MHz
2.0
Model 8614A
1.5
41
Hewlett-Packard
2.5
-110 dBm
Every 1.0 GHz
-90 dBm
Model 8616A
4.0
4.0
52
Polarad
-100 dBm
6.0
-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
72
15.0
-90 dBm
70 dBm
Hewlett-Packard
18.0
Model 628A
18.0
82
Hewlett-Packard
-80 dBm
25.0
-60 dBm
Model 938
Hewlett-Packard
26.5
82
70 dBm
Model 940
40.0
50 dBm
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 connections.
do not exceed 2 divisions in amplitude. (2 average noise
25. Check Amplitude of Spurious Signals from
level.)
Internal Sources
e. Move the 50 Ω termination to band B RF INPUT con-
Requirement-With the DISPERSION RANGE at kHz/DIV
nector and switch the band selector to band B. Change the
for band A, spurious signals must not exceed 2 times noise
DISPERSION RANGE to MHz/DIV and the DISPERSION to
amplitude. With DISPERSION RANGE at MHz/DIV for
10 MHz/div.
bands B and C, spurious signals should be down more than
f. Adjust the GAIN control for an average noise level of
-40 dB with 100 kHz resolution.
1 division, then tune across the entire band, checking for
b. Connect a 50 W termination on band A RF INPUT
spurious signals greater than 2 divisions in amplitude.
connector and switch the band selector to band A.
g. Move the 50 Ω termination to band C RF INPUT con-
c. Set the DISPERSION RANGE to kHz/DIV, the DISPER-
nector. Change the band selector to band C.
SION to 500 kHz/div and the RESOLUTION control fully
h. Measure band C for spurious signals as above.
clockwise.
This concludes the performance check for the Type 491.
d. Adjust the GAIN control for an average noise ampli-
If the instrument has met all checks it is ready to operate and
tude of 1 division then tune the RF CENTER FREQUENCY
will perform to specifications listed in Section 1.
control across the entire band checking that spurious signals
5-13
