Tektronix 1L20, Инструкция по эксплуатации

Страница: 35 / 117

POS
IF ATTEN
IF CENTER FREQ
FINE IF CENTER FREQ
DISPERSION RANGE
DISPERSION-
COUPLED RESOLUTION
VERTICAL DISPLAY
PHASE LOCK
Position the trace to the
bottom line of the
graticule.
ALL OFF
Midrange (000)
Midrange
M H z/C M
1
LIN
I NT 1 MHz REF FREQ
b. Check the Band 1 frequency calibration every 10 MHz
by applying the appropriate —70 dBm signals from the UHF
Signal Generator to the BAND 1 RF INPUT connector.
Maximum error is ± 2 MHz + 1 % of the dial reading for
this step and steps c, d, and e following.
A t the same time, check for phase-lock zero beats about
every 1 MHz by depressing the LOCK CHECK pushbutton
while the RF CENTER FREQ setting is being changed. Check
for a phase-locked display a t 10 MHz, 100 MHz, and 270
MHz.
c. Move the generator output to the BANDS 2-5 RF
INPUT connector and check the dial accuracy a t 275 MHz,
375 MHz, and 475 MHz. Check the phase lock zero beats
as before, and check for a phase-locked display a t 275 MHz
and 500 MHz.
d. Check the dial accuracy a t 500 MHz, 700 MHz, and
900 MHz (using the second harmonic of the signal generator
for 900 MHz). Check for zero beats as before and check for
a phase-locked display at 900 MHz.
e. Since Bands 3, 4, and 5 use harmonics of the Band 2
Local Oscilator output, it follows that if the accuracy of Band
2 is within specifications, then Bands 3, 4 and 5 will also be
within the specifications.
6. Sensitivity and Frequency Range Checks
a. Preset the controls of the
POS
IF ATTEN
DISPERSION RANGE
DISPERSION-
COUPLED RESOLUTION
VIDEO FILTER
VERTICAL DISPLAY
RF INPUT
RF CENTER FREQ
FINE FREQ
Spectrum Analyzer as follows:
Position the trace to the
bottom line of the
graticule.
ALL OFF
kHz/CM
5 (inner ring)
O ff (down)
LIN
BAND 1
10
Fully Clockwise
b. Apply a —30 dBm 10 MHz signal from the UHF Signal
Generator to the BAND 1 RF INPUT connector.
c. Center the signal on the graticule with the Frequency
control of the Signal Generator.
d. Adjust the Analyzer G A IN control until the average
noise level is one division in amplitude.
e. Adjust the RF Attenuator control of the generator so
that the displayed signal is twice as high as the noise level.
(See Fig. 5-2).
Fig. 5 -2 . Typical display for Sensitivity check (Step 6 ) .
f. Check the setting of the RF Atten dial o f the generator.
The signal strength should be —90 dBm or less.
g. Check the sensitivity over the rest o f the frequency
range of the Analyzer as directed in Table 5-1. On bands
2-5, readjust the Analyzer MIXER PEAKING control for maxi­
mum signal amplitude whenever the frequency is changed.
TABLE 5-1
Suggested Signal
G e n e ra to r
(R efer to recom ­
m e n d e d e q u ip ­
ment list)
Frequency
in MHz
Band Sensitivity
(2:1
S ig n a l/
N oise)
Type 608D
10
1
—80 dBm 140
275
275
2 - 9 0 dBm 400
Type 612
900
850
3 —80 dBm
Type 8614
1500
2000
1950
4 - 7 5 dBm
Type 8616
2500
3100
3000
5 - 7 0 dBm 3500
4200
h. When the 100 kHz RESOLUTION display is within the
sensitivity requirements given in Table 5-1, the 1 kHz RESO­
LUTION display will also be within its sensitivity require­
ments.
7. Resolution Check
a. Preset the controls o f the Spectrum Analyzer as follows:
®
5-3