Keysight N2791A User manual

N2791A 25 MHz and
N2891A 70 MHz
High-Voltage
Differential Probes
User’s
Guide

2
Contents
Inspecting the Probe 3
Cleaning the Probe 3
Handling the Probe 3
N2791A/N2891A High-Voltage Differential Probes 4
Contents and Accessory Kits 5
Characteristics 7
Safety Information 9
Using the N2791A High-Voltage Differential Probe 10
Using the N2891A High-Voltage Differential Probe 11
N2791A Plots 12
N2891A Plots 16
Using the Accessories 20
N2791A Performance Verification Procedures 21
N2791A Performance Verification Test Record 23
N2891A Performance Verification Procedures 24
N2891A Performance Verification Test Record 26

3
Inspecting the Probe
Inspecting the Probe
❏Inspect the shipping container for damage.
Keep the damaged shipping container or cushioning material until the contents
of the shipment have been checked for completeness and the probe has been
checked mechanically and electrically.
❏Check the accessories.
• If the contents are incomplete or damaged, notify your Keysight Technologies
Sales Office.
❏Inspect the instrument.
• If there is mechanical damage or defect, or if the probe does not operate
properly or pass calibration tests, notify your Keysight Technologies Sales
Office.
• If the shipping container is damaged, or the cushioning materials show signs
of stress, notify the carrier as well as your Keysight Technologies Sales Office.
Keep the shipping materials for the carrier’s inspection. The Keysight
Technologies office will arrange for repair or replacement at Keysight
Technologies’ option without waiting for claim settlement.
Cleaning the Probe
Disconnect the probe and clean it with a soft cloth. Make sure the probe is
completely dry before reconnecting it to an oscilloscope. Avoid using abrasive
cleaners and chemicals containing benzene or similar solvents.
Handling the Probe
Handle the probe with care and refer to the safety notices at the back of this
manual and on page 9. Note that the probe cable is a sensitive part of the probe
and, therefore, you should be careful not to damage it through excessive bending
or pulling. You should also avoid any mechanical shocks to this product in order
to guarantee accurate performance and protection.
!

4
N2791A/N2891A High-Voltage Differential Probes
N2791A/N2891A High-Voltage Differential Probes
The N2791A/N2891A high-voltage differential probes allow conventional earth-
grounded oscilloscopes to be used for floating signal measurements (up to 700
V of differential or common mode voltage for the N2791A and up to 7000 V of
differential or common mode voltage for the N2891A). The N2791A offers user-
selectable attenuation settings of 10:1 and 100:1 while the N2891A offers
attenuation settings of 100:1 and 1000:1, making both probes highly versatile
and usable for a broad range of applications including power supply
measurements and motor controls. Both probes are compatible with any
oscilloscope with a 1 MW BNC input. The probes can be powered by any USB
port on an oscilloscope or computer, or by internal batteries (4x AA included with
the probe).
The images below show some key parts of the N2891A probe body. The N2791A
has similar switches/LEDs, but they are arranged differently.
Battery Use
• Insert 4 AA batteries in the back of the unit as indicated within the chassis
(see pages 10-11 for information on accessing the battery location)
• When battery life has expired, remove the batteries
• When the batteries gets close to running out, the power indicator will start
to flicker and dim
• Note the WEEE label on the batteries and dispose of properly
on/off switch
power LED
indicator
attenuation
switch
USB power
cord input
overrange
indicator

5
Contents and Accessory Kits
Contents and Accessory Kits
The following table lists the parts included with the N2791A high-voltage
differential probe.
For N2791A replacement accessories, you can order the N2791-68700
Differential Probe Accessory Kit. It includes:
Part Quantity
N2791A 25 MHz differential probe 1
Safety Hook, Red 1
Safety Hook, Black 1
Alligator Clip, Red 1
Alligator Clip, Black 1
USB Power Cord (2 m) 1
AA Battery 4
Trimmer Tool 1
User’s Guide 1
Part Quantity
Safety Hook, Red 1
Safety Hook, Black 1
Alligator Clip, Red 1
Alligator Clip, Black 1
USB Power Cord (2 m) 1

6
Contents and Accessory Kits
The following table lists the parts included with the N2891A high-voltage
differential probe.
For N2891A replacement accessories, you can order the N2891-68700
Differential Probe Accessory Kit. It includes:
Part Quantity
N2891A 70 MHz differential probe 1
Safety Hook, Red 1
Safety Hook, Black 1
High Voltage Alligator Clip, Red 1
High Voltage Alligator Clip, Black 1
USB Power Cord (2 m) 1
AA Battery 4
Trimmer Tool 1
User’s Guide 1
Part Quantity
Safety Hook, Red 1
Safety Hook, Black 1
High Voltage Alligator Clip, Red 1
High Voltage Alligator Clip, Black 1
USB Power Cord (2 m) 1

7
Characteristics
Characteristics
Characteristics for the N2791A and N2891A high-voltage differential probes are
shown below. The probe / oscilloscope should be warmed up for at least 20
minutes before any testing and the environmental conditions should not exceed
the probe’s specified limits.
Electrical Characteristics
N2791A N2891A
Bandwidth (-3 dB) >25 MHz (driving 1 MWoscilloscope
input)
70 MHz (driving 1 MWoscilloscope
input)
Attenuation ratio 10:1, 100:1 (switchable) 100:1, 1000:1 (switchable)
Probe Risetime (10%-90%) 14 ns 5 ns
Absolute Maximum Rated
Input Voltage (each side to
ground)
1000 Vrms CAT II 5000 Vrms CAT I
Maximum Differential Input
Voltage (DC + AC Peak)
\70 V at 10:1 attenuation
\700 V at 100:1 attenuation
\700 V at 100:1 attenuation
\7000 V at 1000:1 attenuation
Maximum Common Mode
Input Voltage
\70 V at 10:1 attenuation
\700 V at 100:1 attenuation
\7000 V at 10:1 attenuation
\7000 V at 1000:1 attenuation
Input Impedance 4 MW, 10 pF (each side to ground)
8 MW, 8 pF (between inputs)
50 MW, 7 pF (each side to ground)
100 MW, 5 pF (between inputs)
Output Voltage Swing \7 V (driving 1 MWoscilloscope input) \7 V (driving 1 MWoscilloscope
input)
Offset (typical) \7.5 mV (adjustable) \5 mV (adjustable)
CMRR (typical) -80 dB at 60 Hz, -40 dB at 1 MHz -80 dB at 50 Hz, -60 dB at 20 kHz
Power Requirements 4 AA batteries or USB power adapter
(5 V/200 mA, 9 V/120 mA)
4 AA batteries or USBpower adapter
(5 V/200 mA, 9 V/120 mA)
Battery Life 15 hours (alkaline battery) 11.5 hours (alkaline battery)
Battery/Power Cord The supplied voltage must be less than
12 V and greater than 4.4 V or else the
probe could be damaged
The supplied voltage must be less
than 12 V and greater than 4.4 V or
else the probe could be damaged
- all are typical

8
Characteristics
Mechanical Characteristics
Environmental Specifications (same for both N2791A and N2891A)
Safety Specifications
N2791A N2891A
Weight (probe only) 400 g (probe and PVC jacket) 500 g
BNC Cable Length 95 cm (37 inches) 90 cm (35 inches)
Length of Input Leads 45 cm (18 inches) 60 cm (24inches)
Dimensions (L x W x H) 170 mm x 63 mm x 21 mm
(6.7 inches x 2.5 inches x 0.83 inches)
202 mm x 83 mm x 38 mm (8.0 inches x
3.3 inches x 1.5 inches)
Temperature Operating: -10 °C to +40 °C
Nonoperating: -30 °C to +70 °C
Altitude Operating: 3,000 m
Nonoperating: 15,300 m
Humidity Operating: 25 - 85% room humidity
Nonoperating: 25 - 85% room humidity
Pollution Degree Pollution Degree 2
CEI/IEC 61010-031 CAT II (N2791A)
CEI/IEC 61010-031 CAT I (N2891A)

9
Safety Information
Safety Information
Warning To avoid personal injury and to prevent fire or damage to this product or products
connected to it, review and comply with the following safety precautions. Be
aware that if you use this probe assembly in a manner not specified, the protection
this product provides may be impaired.
Observe Maximum Working Voltage
To avoid injury, do not use the N2791A probe above 1000 Vrms CAT II (both 10:1
and 100:1 attenuation settings) between each input lead and earth or between
the two input leads. Do not use the N2891A probe above 5000 Vrms CAT I (1000:1
attenuation) or 500 Vrms CAT I (100:1 attenuation) between the two input leads.
Do not use the N2891A probe above 5000 Vrms CAT I (both 100:1 and 1000:1
attenuation settings) between each input lead and earth.
Must be Grounded
Before making connections to the input leads of this probe, ensure that the output
BNC connector is attached to the BNC channel input of the oscilloscope and the
oscilloscope is properly grounded.
Use Fused Test Prods if Necessary
If this probe is intended to be used with circuits of installation category II, it should
incorporate the fused test prods.
Do Not Operate Without Covers
To avoid electrical shock or fire hazard, do not operate this probe with the covers
removed.
Do Not Operate in Wet / Damp Conditions
To avoid electrical shock, do not operate this probe in wet or damp conditions.
Do Not Operate in an Explosive Atmosphere
To avoid injury or fire hazard, do not operate this probe in an explosive
atmosphere.
Avoid Exposed Circuit
To avoid injury, remove jewelry such as rings, watches, and other metallic objects.
Do not touch exposed connections and components when power is present.
!

10
Using the N2791A High-Voltage Differential Probe
Use Proper Power Source
To ensure this probe functions well, use four AA batteries or the supplied USB
power cord.
For Indoor Use Only
Only use this probe indoors.
Do Not Operate With Suspected Failures
If you suspect there is damage to this probe, have it inspected by a qualified
service personnel.
Using the N2791A High-Voltage Differential Probe
• To use this probe, first insert the four AA batteries into the probe or connect
the USB power cord to the probe and a USB port (see page 4 to see where
the USB power cord input is located on the probe).
• Then connect the BNC output connector to the channel input of the
oscilloscope. The oscilloscope must have a ground referenced.
• Select the proper attenuation ratio (10:1 or 100:1) on the probe via the
attenuation switch and specify the attenuation and probe configuration on
your oscilloscope.
TIP: When measuring signals below 70 V, switch the attenuation ratio to 10:1
in order to obtain a higher resolution signal with less noise. Otherwise set the
attenuation ratio to 100:1.
To replace batteries, first slip off
the cover
Then slide the battery cover off
on the rear of the probe

11
Using the N2891A High-Voltage Differential Probe
Using the appropriate probe accessories, connect the inputs to the circuit
under test.
To protect against electrical shock, use only the accessories supplied with
this probe or in the accessory kit.
This probe is to carry out differential measurements between two points on
the circuit under test. This probe is not for electrically insulating the circuit
under test and the measuring instrument.
Using the N2891A High-Voltage Differential Probe
• To use this probe, first insert the four AA batteries into the probe or connect
the USB power cord to the probe and a USB port (see page 4 to see where
the USB power cord input is located on the probe).
• Then connect the BNC output connector to the channel input of the
oscilloscope. The oscilloscope must have a ground referenced.
• Select the proper attenuation ratio (100:1 or 1000:1) on the probe via the
attenuation switch (see the picture on page 4) and specify the attenuation
and probe configuration on your oscilloscope.
TIP: When measuring signals below 700 V, switch the attenuation ratio to
100:1 in order to obtain a higher resolution signal with less noise. Otherwise
set the attenuation ratio to 1000:1.
• Using the appropriate probe accessories, connect the inputs to the circuit
under test.
To protect against electrical shock, use only the accessories supplied with
this probe or in the accessory kit.
This probe is to carry out differential measurements between two points on
the circuit under test. This probe is not for electrically insulating the circuit
under test and the measuring instrument.
Slide the battery cover off the
rear of the probe body
!
!
!
!

12
N2791A Plots
N2791A Plots
Graph of normalized step response (50Ω, 16.5 ns rising edge step generator), 17
ns normalized rising edge (10-90%), 10:1 attenuation
Graph of normalized step response (50Ω, 17 ns rising edge step generator), 17
ns normalized rising edge (10-90%), 100:1 attenuation
-100 -50 050 100 150
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Time (ns)
Volts
Step Input
Signal
Measured Step
Response
(17 ns 10-90%
rise time)
-100 0100 200 300 400 500
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Time (ns)
Volts
Step Input
Signal
Measured Step
Response
(17 ns 10-90%
rise time)

13
N2791A Plots
Graph of dB(Vin), dB(Vout) + 20dB, and dB(Vout/Vin) + 20dB frequency response,
10:1 attenuation
Graph of dB(Vin), dB(Vout) + 40dB, and dB(Vout/Vin) + 40dB frequency response,
100:1 attenuation
10
0
10
1
-20
-15
-10
-5
0
5
Frequency (MHz)
dB
Vout
Vin
Vout/Vin
10
0
10
1
-10
-7.5
-5
-2.5
0
2.5
5
Frequency (MHz)
dB
Vout/Vin
Vout
Vin

14
N2791A Plots
Graph of dB(Vout/Vin) + 20dB frequency response when inputs driven in common
mode (common mode rejection), 10:1 attenuation
Magnitude plot of probe input impedance versus frequency (single-ended mode)
10
2
10
3
10
4
10
5
10
6
10
7
10
8
-100
-80
-60
-40
-20
Frequency (Hz)
dB
10
6
10
7
10
8
10
9
10
2
10
3
10
4
10
5
Frequency (Hz)
Ω
22 pF

15
N2791A Plots
Typical derating plot of the absolute maximum input voltage in common mode
10
6
10
7
100
300
500
700
900
1100
Frequency (Hz)
Vrms

16
N2891A Plots
N2891A Plots
Graph of normalized step response (50 W, 10 ns rising edge step generator), 10
ns normalized rising edge (10-90%), 100:1 attenuation
Graph of normalized step response (50 W, 10 ns rising edge step generator), 10
ns normalized rising edge (10-90%), 1000:1 attenuation
-20 020 40 60 80 100
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Time (nS)
Normalized Step Response (V)
Step Input Signal
Probe Step Response
(10 ns 10-90% rise time)
-20 020 40 60 80 100
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Time (nS)
Normalized Step Response (V)
Step Input Signal
Probe Step Response
(10 ns 10-90% rise time)

17
N2891A Plots
Graph of dB (S21) + 40 dB frequency response, 100:1 attenuation
Graph of dB (S21) + 60 dB frequency response, 1000:1 attenuation
10
0
10
2
10
4
10
6
10
8
-35
-30
-25
-20
-15
-10
-5
0
5
Frequency Hz
Normalized S21+40dB
10
0
10
2
10
4
10
6
10
8
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
Frequency Hz
Normalized S21+60dB

18
N2891A Plots
Graph of dB (S21) + 40 dB frequency response when inputs driven in common
mode (common mode rejection), 100:1 attenuation
Magnitude plot of probe input impedance versus frequency, single-ended and
differential
10
2
10
4
10
6
10
8
-90
-80
-70
-60
-50
-40
-30
-20
-10
Frequency (Hz)
CMRR dB
10
0
10
2
10
4
10
6
10
8
10
3
10
4
10
5
10
6
10
7
10
8
10
9
10
10
Frequency (Hz)
Input impedance (Ohms)
5 pF
7.2 pF
differential
single-ended

19
N2891A Plots
Typical derating plot of the absolute maximum input voltage in common mode
Input impedance equivalent circuit diagram
10
5
10
6
10
7
10
8
10
1
10
2
10
3
10
4
Frequency(Hz)
Vrms

20
Using the Accessories
Using the Accessories
The accessories supplied with the N2791A and N2891A probes are attached by
pushing them onto the probe leads as shown below.
The following accessories are supplied with the N2791A probe and with the
N2791-68700 Accessory Kit.
Safety Hook and Alligator Clips
Use the safety hooks to clamp onto smaller components and use the alligator
clips to clamp onto thicker gauge devices
The following accessories are supplied with the N2891A probe and with the
N2891-68700 Accessory Kit.
Safety Hook and High-Voltage Alligator Clips
Use the safety hooks to clamp onto smaller components and use the alligator
clips to clamp onto thicker gauge devices
hook or clip
probe lead
safety hook alligator clip
safety hook high-voltage alligator clip