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The Keysight N2790A is a 100 MHz high-voltage differential probe designed to let conventional earth-grounded oscilloscopes make safe and accurate floating measurements. It is part of a three-probe family that also includes the N2791A (25 MHz) and N2891A (70 MHz), each rated for different differential and common-mode voltage ranges. The N2790A specifically uses a differential amplifier in the probe head and is rated to measure differential voltage up to 1400 VDC + peak AC.
Oscilloscope users often need to make floating measurements where neither point of the measurement is at earth ground. The N2790A is built for exactly this case — supporting the floating measurements found in power electronics circuits where direct earth-referenced probing is not safe or practical. Its selectable 50:1 and 500:1 attenuation settings make it versatile across a range of applications, and the included probe tip accessories allow access to both small and large components in tight places.
ValueTronics has supplied new and pre-owned test and measurement equipment from our 20,000 sq ft secure warehouse at 1675 Cambridge Drive, Elgin, Illinois since 1992. Every instrument we offer is held, inspected, and tested by our own technicians on-site — not drop-shipped from third parties or pulled from a broker's pass-through inventory. When you order an N2790A from ValueTronics, the probe ships from our facility with documented condition and ValueTronics accountability behind it.
Keysight Technologies traces its measurement heritage to Hewlett-Packard, founded in 1939. HP spun off its test and measurement, semiconductor products, and chemical analysis businesses as Agilent Technologies in 1999. In 2014, Agilent separated its electronic measurement business into a new company, Keysight Technologies, which continues the test and measurement product lines today.
The N2790A is one of three high-voltage differential probes in the family covered by this datasheet. The N2791A (25 MHz, ±700 V differential at 100:1) and N2891A (70 MHz, ±7000 V or 5000 Vrms differential at 1000:1) round out the lineup. All three probes are designed to let conventional earth-grounded oscilloscopes make safe and accurate floating measurements — the differences lie in bandwidth, voltage rating, attenuation options, oscilloscope interface, and power source.
The family covers a range of floating-measurement applications, from lower-voltage signal-integrity work (N2791A) through general power electronics (N2790A) to high-voltage applications requiring kilovolt-class differential capability (N2891A). Selecting between them depends primarily on the differential and common-mode voltage levels in your application and the bandwidth needed to capture the signals of interest.
Each new probe in this family is listed on its own product page with condition-matched pricing and accessory availability. Use the comparison table below to confirm specifications, then visit the individual model page for current pricing and ordering details.
The N2790A occupies the middle ground in the family: 100 MHz bandwidth, ±1400 V differential capability at 500:1, and the AutoProbe interface for direct oscilloscope-powered operation. Its DC CMRR of -70 dB at 500 VDC and AC CMRR figures (-80 dB at 50/60 Hz, -50 dB at 1 MHz) target it at power electronics floating measurements where both bandwidth and common-mode rejection matter.
The three probes differ across four primary axes. Bandwidth: 25 MHz (N2791A), 70 MHz (N2891A), 100 MHz (N2790A). Maximum differential operating voltage: ±700 V at 100:1 (N2791A), ±1400 V at 500:1 (N2790A), ±7000 V or 5000 Vrms at 1000:1 (N2891A). Attenuation options: 10:1/100:1 (N2791A), 50:1/500:1 (N2790A), 100:1/1000:1 (N2891A).
Power source also differs: the N2790A draws power directly from the AutoProbe interface, while the N2791A and N2891A use either 4× AA batteries or a supplied USB power cable from the scope or PC. The comparison table that follows lays out the specifications side-by-side so you can match the right probe to your application's voltage, frequency, and oscilloscope interface requirements.
| Model | Bandwidth | Max Differential Voltage | Attenuation |
|---|---|---|---|
| N2790A | 100 MHz | ±1400 V (DC + Peak AC) | 50:1 / 500:1 |
| N2791A | 25 MHz | ±700 V (DC + Peak AC) | 10:1 / 100:1 |
| N2891A | 70 MHz | ±7000 V or 5000 Vrms at 1000:1 | 100:1 / 1000:1 |
Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.
| Specification | N2790A | N2791A | N2891A |
|---|---|---|---|
| Bandwidth (−3 dB) | ≥ 100 MHz | ≥ 25 MHz | ≥ 70 MHz |
| Rise time (calculated) | ≤ 3.5 ns | ≤ 14 ns | ≤ 5 nsec |
| Attenuation | 50:1 / 500:1 | 10:1 / 100:1 | 100:1 / 1000:1 |
| Gain accuracy (% of reading) | ± 2% at 20 to 30 °C; ± 4% at 0 to 20 °C and 30 to 50 °C | ± 2% at 20 to 30 °C; ± 4% at 0 to 20 °C and 30 to 50 °C | ± 2% at 20 to 30 °C; ± 4% at 0 to 20 °C and 30 to 50 °C |
| DC CMRR | −70 dB at 500 VDC | — | — |
| AC CMRR | −80 dB at 50/60 Hz; −50 dB at 1 kHz; −50 dB at 1 MHz | −80 dB at 50/60 Hz; −40 dB at 1 MHz | −80 dB at 50/60 Hz; −60 dB at 20 kHz |
| Propagation delay | 14 nsec at 50:1; 2.8 nsec at 500:1 | — | — |
| Input R//C (each input to ground) | 4 Mohm // 7 pF | 4 Mohm // 10 pF | 50 Mohm // 7 pF |
| Input R//C (between inputs) | 8 Mohm // 3.5 pF | 8 Mohm // 8 pF | 100 Mohm // 5 pF |
| Max differential operating voltage (DC + Peak AC or RMS) | ± 1400 V at 500:1; ± 140 V at 50:1 | ± 700 V at 100:1; ± 70 V at 10:1 | ± 7000 V or 5000 Vrms at 1000:1; ± 700 V or 700 Vrms at 100:1 |
| Max common mode operating voltage (DC + Peak AC or RMS) | ± 1000 V (CAT II); ± 600 V (CAT III) | ± 700 V at 100:1; ± 700 V at 10:1 | ± 7000 V or 5000 Vrms at 1000:1; ± 7000 V or 5000 Vrms at 100:1 |
| Max nondestructive voltage | ± 1500 VDC + Peak AC differential mode; ± 1300 Vrms (CAT II) common mode | ± 1000 Vrms (CAT II) differential and common mode | ± 7000 V (DC + Peak AC); ± 5000 Vrms at 1000:1 and 100:1 in differential and common mode (Main Isolated) |
| Output maximum voltage range | ± 2.8 V into 1 Mohm (500:1) | 7 V into 1 Mohm (100:1) | 7 V into 1 Mohm (1000:1) |
| Scope's input impedance | 1 Mohm AutoProbe interface | 1 Mohm BNC interface | 1 Mohm BNC interface |
| Output offset | Adjustable | ± 7.5 mV (typical) | ± 5 mV (typical) |
| Noise referenced to input | < 300 mVrms at 500:1; < 50 mVrms at 50:1 | — | — |
| Temperature - operating | −10 to 50 °C | −10 to 40 °C | −10 to 40 °C |
| Temperature - non-operating | −51 to 71 °C | −30 to 71 °C | −30 to 71 °C |
| Humidity - operating | 80% RH at 40 °C | 25 to 85% RH | 25 to 85% RH |
| Humidity - non-operating | 90% RH at 65 °C | 25 to 85% RH | 25 to 85% RH |
| Operating altitude | 2,000 m | 3,000 m | 3,000 m |
| Nonoperating altitude | 15,300 m | 15,300 m | 15,300 m |
| Vibration | Keysight class GP and MIL-PRF-28800F class 3 random | ||
| Shock | Tip end: 400g 1/2 sine wave; AutoProbe BNC End: 50g 1/2 sine wave; Probe circuit box: Keysight class B1 and MIL-PRF-28800F class 3 | ||
| Safety specifications | IEC61010-031 | IEC61010-031 | IEC61010-031 |
Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.
Model No
Keysight
Condition
New
Manufacturer
Keysight
Frequency
100 MHz
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