The Keysight N8485A is a high-performance thermocouple power sensor designed for accurate RF and microwave power measurements. Operating across a wide frequency range from 10 MHz up to 26.5 GHz (or up to 33 GHz with Option 033), it offers high linearity, exceptional SWR performance, and compatibility with a wide range of legacy and modern Keysight/Agilent power meters. Available in standard EEPROM-calibrated (Option STD) and printed calibration table (Option CFT) variants, it is an essential tool for precise power characterization in laboratory, manufacturing, and field environments.
Specifications
General
| Parameter | Value |
|---|---|
| Interfaces | Multipin sensor connector (compatible with Keysight 11730 series cables) |
| Display | None (utilizes compatible power meter display) |
| Sensor Technology | Thermocouple |
Physical
| Parameter | Value |
|---|---|
| Power Supply | Power supplied directly from compatible power meter |
| Operating Temperature | 0 to 55 °C |
| Dimensions (W×H×D) | 38 mm x 30 mm x 135 mm |
| Weight | 0.181 |
Performance
| Parameter | Value |
|---|---|
| Frequency Range (Standard) | 10 MHz to 26.5 GHz |
| Frequency Range (Option 033) | 10 MHz to 33 GHz |
| Power Measurement Range | -35 dBm to +20 dBm (224 nW to 100 mW) |
| Maximum Continuous Input Power | +25 dBm (300 mW) |
| Maximum Peak Input Power | 15 W (for pulse width < 10 µs) |
| Maximum DC Input Voltage | 20 VDC |
Standing Wave Ratio (SWR)
| Parameter | Value |
|---|---|
| Maximum SWR (10 MHz to 50 MHz) | 1.15 |
| Maximum SWR (50 MHz to 100 MHz) | 1.10 |
| Maximum SWR (100 MHz to 2 GHz) | 1.13 |
| Maximum SWR (2 GHz to 12.4 GHz) | 1.18 |
| Maximum SWR (12.4 GHz to 18 GHz) | 1.25 |
| Maximum SWR (18 GHz to 26.5 GHz) | 1.29 |
| Maximum SWR (26.5 GHz to 33 GHz) | 1.34 (Option 033) |
Linearity
| Parameter | Value |
|---|---|
| Power Linearity (-35 to -1 dBm, Option STD) | ±0.52% |
| Power Linearity (-1 to +15 dBm, Option STD) | ±0.80% |
| Power Linearity (+15 to +20 dBm, Option STD) | ±1.41% |
| Power Linearity (-35 to -1 dBm, Option CFT) | ±0.80% |
| Power Linearity (-1 to +15 dBm, Option CFT) | ±1.24% |
| Power Linearity (+15 to +20 dBm, Option CFT) | ±1.84% |
Zeroing & Noise
| Parameter | Value |
|---|---|
| Zero Set | ±25 nW |
| Zero Drift | < ±10 nW (within 1 hour at constant temperature) |
| Measurement Noise | < 80 nW |
Physical & Mechanical
| Parameter | Value |
|---|---|
| RF Input Connector | 3.5 mm male |
| RF Connector Torque Limit | 90 N-cm (8 in-lb) |
System Connectivity
| Parameter | Value |
|---|---|
| Compatible Cable Type | Keysight 11730 series cables |
| Compatible Power Meters | Keysight EPM (N1913A/14A, E4418B/19B), EPM-P (E4416A/17A), and P-Series (N1911A/12A) |
System Compatibility
| Parameter | Value |
|---|---|
| Calibration Storage (Option STD) | EEPROM (no manual calibration table entry required) |
| Calibration Storage (Option CFT) | Calibration factor table printed on sensor chassis |
Environmental
| Parameter | Value |
|---|---|
| Storage Temperature Range | -40 °C to +70 °C |
| Operating Humidity Range | Up to 95% RH at 40 °C (non-condensing) |
| Storage Humidity Range | Up to 90% RH at 65 °C (non-condensing) |
| Operating Altitude | Up to 4,600 meters (15,000 feet) |
| Storage Altitude | Up to 15,240 meters (50,000 feet) |
| Vibration (Operating) | Random: 5 to 500 Hz, 0.21 g rms |
| Vibration (Non-Operating) | Random: 5 to 500 Hz, 2.09 g rms; Swept Sine: 0.5G, 5 to 500 Hz |
| Shock (Non-Operating) | Half-sine pulse: 400G, 2 ms |
Compliance & Certifications
| Parameter | Value |
|---|---|
| EMC Compliance | Complies with IEC 61326-1 / EN 61326-1, CISPR 11 / EN 55011 Class A |
| Safety Standards | Complies with IEC 61010-1 / EN 61010-1 |
Ordering Information
| Parameter | Value |
|---|---|
| Option STD Description | Standard configuration featuring integrated EEPROM calibration |
| Option CFT Description | Legacy compatibility option with printed calibration factor table |
| Option 033 | Frequency range expansion up to 33 GHz |
| Option 1A7 | ISO 17025 compliant calibration certificate |
| Option A6J | ANSI Z540 compliant calibration certificate |
| Option UK6 | Commercial calibration certificate with test data |
RF Characteristics
| Parameter | Value |
|---|---|
| Nominal Impedance | 50 Ω |
Technology
Thermocouple RF Power Measurement
Applications
RF and Microwave Power Measurement