User manual

Service Information
Circuit Descr
iption
This section describes the circuits in the P6022 current probe and termination.
Current Probe
The P6022 current probe consists of a current transformer m ounted in the nose of
the probe head case, an impedance-matching network, and an internal switch to
disconnect the transformer shield from ground.
The transformer contains a two-section, U-shaped ferrite core. One section is
stationary; the other is mechanic ally movable to permit closing th e core around
the c onductor being measured. The conductor under test forms a one-turn primary
winding f
or the transformer; the windings a round the stationary portion of the
core are the secondary windings. The circuitry between the transformer and the
coaxial cable corrects any differences in level between the pulses induced in the
windings of the secondary, and matches the balanced probe winding to the cable.
As indicated on the probe body, the turns ratio of the P6022 is 50:1. This refers to
the number of windings in the secondary of the probe transformer.
The probe transformer is shielded to eliminate interference from outside signals.
To eliminate the possibility of creating a short circuit from this shield to the
conductor being measured, the slide switch disconnects the ground from the
shield when you open the sliding portion of the probe to connect or remove it
from
a conductor.
Termination
The P6022 termination consists of an impedance-matching network to te rminate
the coaxial cable, and a voltage divider that is switched in by a sensitivity control
to
change the sensitivity by a factor of five. When the control is in the 1 mA/mV
position, a 10 mA current signal in the conductor under test induces a 10 mV
signal at the output of the termination. (This assumes that the termination is
connectedtoa1MΩ input oscilloscope.)
When the sensitivity control is in the 10 mA/mV position, a 10 mA current signal
is attenuated to induce a 1 mV signal at the output of the termination.
12 P6022 Instruction Manual