Checks and Adjustments
1705A Spectrum Monitor 5-7
c. Connect the leveled sine wavegenerator output to the comb generator.
Connect the comb generatoroutput to the 1705A rear-panel 70 MHz
INPUT. SeeFigure 5-1.
2. CheckPower Supply Operation
REQUIREMENT— Check ac input range, 90 -- 250 V.
a. Set the leveledsine wave generator Frequency to 5.0 MHz, the
Amplitude Multiplier to X1, and theAmplitude to 4.0 (+16 dBm).
b. Adjust the controls for a usable display.
c. Varythe autotransformer from low-line to high-line voltage(90 - 132 V
for 110V, or 180 - 250 V for 220 V operation).
d. CHECK-- for stable operation over the prescribed voltage range. (Note:
If the LNB POWER is on and in use, the requirementis derated to 100 --
132 V or 200 --250 V.)
e. Return the autotransformerto the local nominal mains voltage.
3. CheckLNB Power Supply
REQUIREMENT— +18 Vdc ±5%.
a. Connect DVM leads between the centerconductor of the L--BAND
INPUT connector and ground.
b. Turnon the LNB POWER switch.
c. CHECK -- that the rear-panel, LNB POWER L ED is ON, and that the
DVM reads +18V ±0.9 V.
d. Temporarily(approximately 2 seconds) short the L--BANDINPUT
connectorcenter conductor to ground.
e. CHECK -- that the red indicator lamp extinguishes and then comes back
on when the short is removed.
f. TurnLNB POWER off.
CAUTION. The LNB POWER switch MUST be turned off for therest of this
procedure to prevent damage to the generators used in later steps.
4. Check 70 MHz Linearity
REQUIREMENT— One marker per Division ±1 minor Division.