33
10.2
Sample flow unit: 15 way D-connector
(labelled “Cryojet dewar leg”)
Component Pins on 15
way D-
connector
Pins on 4-pin round
connector fixed to
dewar leg of
sample flow unit
Typical
resistance
between pins,
(when
disconnected
from
controller),
ohms
Typical output
of controller
measured using
the spare socket
“Shield unit”,
when sample
flow unit is
plugged in
Boiloff heater 1 and 9 1 and 2 35 - 40 up to about 40
volts,
proportional to
the square root
of the flow
10.3
Sample flow unit 9-way D-connector
(labelled “Coldhead”)
Component Pins on 9
way D-
connector
Pins on round
(Fischer)
connectors fixed to
coldhead
Typical
resistance
between pins,
(when
disconnected
from
controller),
Typical output of
controller
measured when
D-plug is
removed
Heat
exchanger
heater
6 and 7 1 and 2 of 10-pin
connector
35 - 40 ohms usually 0 - 2 V
Platinum
sensor,
voltage leads
1 and 2 1 and 2 of 4-pin
connector
about 105
ohms at room
temp, falling to
20 ohms at 70
K
undefined
Platinum
sensor,
current leads
4 and 5 3 and 4 of 4-pin
connector
about 105
ohms at room
temp, falling to
20 ohms at 70
K
typically 20 to 30
V
Leads for
platinum
sensor
1 and 4
(and 2 and
5)
1 and 3 (and 2 and
4) of 4-pin
connector
about 1 ohm undefined
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