Tektronix P7313, P7350, P7360, P7360A, P7380 User manual

Precautions When Handling Probe Cables

Tektronix P7300 & P7500 Series probes are quality measurement tools and
should be treated with care to avoid damage or performance degradation due to
mishandling

Never over-bend the probe main or tip cables, which can put a permanent
kink into th
to use the protective foam carrying case which is designed to not exceed the
minimum bend radius of 2.5 inches.

To maximize probe life, limit the amount of cable twist relative to the probe
control box to ±180 degrees. Always uncoil a probe cable gently before
applying the twisting forces needed to orient the probe head for connection
to the probe tip.

. Take the following precautions when handling the probe cables:

e cable. When storing the probe do not coil it too tightly. It is best

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Do not excessively pull or twist the probe cables when positioning the probe

measurements.

for

Never crush the cable, as will occur when you run over the probe with a chair

el or drop something heavy on the cable.

whe

*P071269700*

071-2697-00

Precautions When Handling Probe Cables

Cable Topology and

Description

Tektronix P730
measured signals from the probe tip to the oscilloscope vertical channel input.
The probe main cable connects the probe head to the probe control box, which
attaches to the oscilloscope. This main cable is a composite of a coaxial signal
cable surrounded by a group of small power and control wires. The probe tip
cables connect the probe head to the connection point on the DUT (Device
Under Test)
provide a more flexible connection to the DUT. These probe cables are all high
performance compone nts that need to be handled with care in order to preserve
probe performance.

A flexible coaxial cable is composed of a center-conductor wire surrounded by a
cylindrical dielectric, which is in turn surrounded by an outer conductor shield
wrapped with an insulating plastic jacket. The center conductor wire is often
stranded for greater flexibility and the outer conductor shield may be as simple
as a sing
better performance.

le braid or a more complex structure with multiple shielding layers for

0 & P7500 Series probes use several coaxial cables to transfer

. The probe tip cables are smaller than the main cable in order to

A coaxial cable is a transmission line structurewhichisusedtotransferahigh
frequency signal with minimum distortion. Low distortion signal transmission
requires stable characteristic impedance along the entire length of the cable path.
The stability of a cable’s characteristic impedance depends on the uniformity

he dielectric layer shape separating the center conductor wire from its

of t
surrounding shield conductor. The characteristic impedance also depends on the
uniformity of the shield layer conductors which are securely wrapped around the
dielectric layer. Because the cable dielectric layer is a soft plastic material it is
subjecttopossibledamageifthecableisstressed due to mishandling. Similarly
the shield layer conductors are relatively fine wire structures that can be distorted

nto a non-uniform set due to mishandling overstress. Overstress can occur due to

i
bending, twisting, pulling, or crushing of the cable.

The probe cables are low-loss cables with a relatively complex outer shield
structure that is susceptible to overstress due to twisting. Since the dielectric layer
of a cable is typically a flexible structure, it is generally not stressed excessively
when a cable is twisted. The shield conductor is usually stiff enough that it can be
permanently distorted if overstressed beyond its elastic limit. This is particularly
true when a cable is twisted while still in a coiled shape, where the cable shield
is already in a stressed condition. Always allow the probe cable to gently uncoil
completely prior to use. It is also important to recognize that the probe main cable
is captured mechanically at the control box and that twisting of the cable relative
to that anchor point should be limited to ±180 degrees for maximum cable life.

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