Tektronix 1L30 Instruction Manual page 14

Operating instructions— Type 1L30
turn the RESOLUTION control to the coupled position with
■
the DISPERSION selector.
■ I
&
GENERAL OPERATING INFORMATION
Signal Application
I
Signals applied to the RF INPUT connector should be
applied through a 50-ohm coaxial cable with a N type
connector. Impedance mismatches between the signal source
and the RF INPUT connector, due to signal source output
i $ impedance, long coaxial cables, due to signal source output
affect on display flatness.
sired and signal strength is adequate, a 50 ft attenuator pad
(such as 10 dB pad) should be added between the signal
source and the RF INPUT connector.
the reflections and optimize display flatness.
Signal input power to the analyzer should not exceed
—30 dBm. Signals above this level may overload the 1st
mixer and/or the 1st IF stage and generate spurious sig­
nals on the display. Add at least 10 dB attenuation to the
input when signal compression is noticed (no increase in
signal height with an increase in input power). A conver-.
sion chart (Fig. 2-6) may be used to calculate input signal
levels.
Signals whose amplitudes are g reater than
dBm applied to the INPUT may d am age the diode
mixers.
3
■ 1
:4
i
2 - 8
When optimum flatness is de­
This will minimize
C A U TIO N
+ 1 5
Fig. 2-6. Volts-dBm-Wafts conversion chart for 50 ft impedance.
Front Panel Calibration Adjustments
Three screwdriver adjustments provide a means to cali­
brate the DISPERSION, IF CENTER FREQ and the DISPER­
SION RANGE balance. These front panel adjustments must
be recalibrated whenever the Type 1L30 is shifted to an­
other oscilloscope, to compensate for differences in sawtooth
amplitudes and CRT deflection sensitivities.
visable to check the adjustments periodically during regu­
lar use. Adjustment and a calibration check procedure may
be performed as follows:
1. Balance and Calibration Check
a. Set the INT 1 MHz REF FREQ switch in the OFF posi­
tion, then tune a signal on screen with the RF CENTER FREQ
control.
b. Tune for minimum signal
RANGE is switched from M H z /C M
c. W ith the DISPERSION RANGE selector at the M H z/C M
position, adjust the IF CENTER FREQ control for minimum •
signal' shift as the DISPERSION selector is switched through
the 10 to .2 M Hz positions.
d. Set the DISPERSION RANGE selector to kH z/C M posi­
tion. Continue adjusting the IF CENTER FREQ control for
minimum signal shift as the DISPERSION is switched from
500kHz/cm to 5kH z/cm .
e. Set the DISPERSION to the 500 kHz/cm position, then
center the signal in the graticule area with the Horizontal
Position control. Check the signal position on the sweep.
The signal should locate within ± 1 cm of the sweep center
It is also ad­
shift as the DISPERSION
to kH z/C M positions.
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