Electromagnetic Interference - Avtech AV-1022-C-AS4 Instructions Manual

ELECTROMAGNETIC INTERFERENCE
To prevent electromagnetic interference with other equipment, all used outputs
should be connected to shielded 50 Ohm loads using shielded 50 Ohm coaxial cables.
Unused outputs should be terminated with shielded 50 Ohm BNC terminators or with
shielded BNC dust caps, to prevent unintentional electromagnetic radiation.
TOP AND BOTTOM COVER REMOVAL
The top cover of the instrument may be removed by removing the four Phillips
screws on the top panel. With these four screws removed, the top panel may be slid off
by pulling it towards the rear. The bottom panel may be similarly removed.
USER-ACCESSIBLE INTERNAL ADJUSTMENTS
Several trimming potentiometers are accessible inside the instrument to tweak
the duty cycle protection circuit, and to null any voltage offsets present on the output
waveform. These potentiometers are factory-set and should not normally require any
adjusting. These controls can be accessed by removing the top panel, and by locating
the large, horizontal board mounted on the left-side and the front panel of the
instrument.
If an amplitude-independent offset is present on the output waveform, this can
be nulled by adjusting the potentiometer labeled "OFFSET1". (The potentiometer may
be obscured by a ribbon cable. Simple move the ribbon cable out of the way.) If an
amplitude-dependent offset in excess of t+20mV is present on the output waveform, this
can be nulled by adjusting the potentiometer labeled "OFFSET2".
Three separate duty-cycle adjustment controls are present, and are labeled
"DUTY 1", "DUTY2", and "DUTY3". Each corresponds to a different pulse width range:
Adjust this control to protect this PW range
DUTY1 0.05 us - 0.5 ps
DUTY2 0.5 us - 5 us
DUTY3 5 ps - 50 ps
If the protection circuit is being triggered at duty cycles outside of the 43% - 47% range
for one (or more) of the PW ranges, adjust the appropriate "DUTY" potentiometer(s).