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2.3.2.2 ZN50-Compatible Probe Cables and Connectors
ZN50 probe cables with their signal connector and probe connector dominate the
electrical characteristics of DC/RF configurations. Each combination has different
electrical properties, but they are all compatible with the ZN50 series of probes.
1.
BNC feedthrough with ultra-miniature cryogenic coaxial cable:
for general purpose DC/
RF applications. The BNC signal connector on the probe arm base is easy and
economical to interface. Shielding at system ground potential is carried to the
probe’s ceramic blade. Teflon®-insulated, ultra-miniature cryogenic coaxial cable
provides operation up to 50 MHz and 500 K with low thermal conductivity. The
probe arm sensor should be monitored when probing a sample above this
temperature. SMA probe connectors mate with ZN50 series probes.
2.
Triaxial with ultra-miniature cryogenic coaxial cable:
for low leakage applications. The
triaxial signal connector on the probe arm base permits an active guard to be
carried to the probe’s ceramic blade. The outermost contact connects electrically
to the chamber to provide a shield. The centermost contact is the signal contact,
and the contact between the signal and the shield is the guard contact. The
connector’s signal to guard resistance is specified at >10 G
)
and is typically
>50 G
)
when it is clean and dry. The impact of leakage current on measurement
uncertainty is further reduced by proper guarding. The Teflon®-insulated,
ultra-miniature cryogenic coaxial cable provides operation up to 50 MHz and
500 K with low thermal conductivity. The probe arm sensor should be monitored
when probing a sample above this temperature. SMA probe connectors mate
with ZN50 series probes.
3.
K-connector with semirigid coaxial cable:
for high frequency applications. The SMA
connectors on ZN50 series probes are physically compatible with the
K-connectors on 40 GHz microwave cables. This cable configuration enables
ZN50 probes to be used continuously up to 100 MHz and at selected bands up to
1 GHz. ZN50 series and 40 GHz microwave probes can be interchanged without
rewiring the probe arm. Some limitations apply: a ZN50-26U probe mount is
required in the Model CRX-6.5K for the ZN50 blades. Semirigid microwave cables
are limited to operation below 350 K and are more thermally conductive than
ultra-miniature coaxial; therefore, the probe arm sensor should be monitored
when probing a sample above this temperature. The cable’s outer conductor is
grounded to the thermal anchor point of the probe arm shield. See section 2.4.3
for further information on the RF performance of the ZN50 probe.
FIGURE 2-12
ZN50 probe and mount
