Technical data subject to change.
© Cal Test Electronics 2017. caltestelectronics.com
Datasheet CT3684/CT3685
High Voltage
Di erential Probe
50 MHz / ±700 V (CT3684)
50 MHz / ±1400 V (CT3685)
Overview:
Differential probes allow safe, accurate measurement between two voltage points where neither
point is referenced to ground. The CT3684 and CT3685 both offer 50 MHz bandwidth and can
test up to ±700 V (DC + AC peak) and ±1400 V (DC + AC peak), respectively. Compatible with
oscilloscopes from all major manufacturers, the probes are powered by the included 9 VDC adapter.
Features:
■ 50 MHz bandwidth (-3 dB)
■ Up to ±700 V (DC + AC peak) common
mode (CT3684)
■ Up to ±1400 V (DC + AC peak) common
mode (CT3685)
■ Attenuation settings of 10x (CT3684) and
100x (CT3685)
■ High accuracy (±1%)
■ High CMRR
■ Power indicator LED
■ 9 VDC adapter, CT3723 (included)
■ USB power lead, CT4122 (optional)
■ Battery pack with 4 AA batteries, CT3729
(optional)
CT3684 shown
Technical data subject to change.
© Cal Test Electronics 2017. caltestelectronics.com
Electrical Specifi cations
CT3684 CT3685
Bandwidth (-3dB) 50 MHz (driving 1 MΩ oscilloscope input)
Rise Time (10%-90%) 7 ns
Attenuation ratio 10x 100x
Accuracy ±1%
CMRR (typical) -90 dB @ 60 Hz
-55 dB @ 1 MHz
Maximum Differential Input
Voltage
(DC + AC peak)
±70 V ±700 V
Maximum Common Mode Input
Voltage
(DC + AC peak)
±700 V ±1400 V
Absolute Maximum Rated Input
Voltage (each side to ground) 500 Vrms CAT I 1000 Vrms CAT II
Input Impedance 1.6 MΩ // 7 pF (each side to
ground)
4.0 MΩ // 7 pF (each side
to ground)
Output Voltage Swing ±7 V (driving 1 MΩ oscilloscope input)
Offset (typical) ±2 mV ±1 mV
Noise (typical) 0.7 mVrms 0.3 mVrms
Source Impedance 50 kΩ
Power Supply
CT3723 power adapter (included) or
4 AA batteries (optional)
CT4122 USB power lead (optional)
Mechanical Characteristics
Weight 300 g
Dimensions 111 x 22 x 14 mm
BNC Cable Length 125 cm
Input Leads Length 50 cm each
Environmental Characteristics
Operating Temp/Humidity -10°C to 40°C / Up to 85% RH
Storage Temp/Humidity -30°C to 70°C / Up to 85% RH
Pollution Degree Pollution Degree 2
Altitude Operating: 3,000 m
Nonoperating: 15,300 m
Safety Specifi cations
IEC 61010-031 CAT I (CT3684) CATII (CT3685)
