Used RF & Microwave Noise Sources for Sale
16 units in stock — Keysight, Agilent, and Noisecom noise sources from 10 MHz to 26.5 GHz. All units include ENR data. NIST-traceable ENR recalibration available.
Agilent / Keysight Noise Sources (8 units)
HP / Agilent Noise Sources (2 units)
Keysight / Agilent Noise Sources (5 units)
Rohde & Schwarz Noise Sources (1 unit)
Noise Source Model and Frequency Range Reference
Every noise figure measurement requires a noise source with an ENR that is calibrated at the measurement frequency. Keysight is the dominant supplier in this category and the 346/N4000 families are the most widely installed in working labs. The N4000A replaces the 346A with a smaller form factor and 2.4 mm connector; the two are functionally equivalent for most bench work.
| Model | Frequency | Nominal ENR | Connector |
|---|---|---|---|
| 346A / N4000A | 10 MHz – 18 GHz | 15 dB | APC-7 / 2.4 mm |
| 346B / N4001A | 10 MHz – 18 GHz | 23 dB (high ENR) | APC-7 / 2.4 mm |
| 346C / N4002A | 10 MHz – 26.5 GHz | 15 dB | APC-7 / 2.4 mm |
| Noisecom NC3000 | 0.01 Hz – 2 GHz | Broadband | SMA |
ENR Documentation and What Comes With the Unit
Every noise source we sell includes the ENR data sheet. For most Keysight units this is the original factory calibration data that is printed on the unit or supplied on a floppy disk / certificate. ENR recalibration traces back to NIST thermal noise standards and typically costs $200–$400 per source. We recommend recalibration for any noise source where the ENR certificate is more than 3 years old, particularly for noise figure measurements below 3 dB.
Frequently Asked Questions
What is the difference between the Keysight 346A, 346B, and 346C noise sources? +
The 346A covers 10 MHz to 18 GHz with a nominal ENR of 15 dB. The 346B covers the same range with a higher ENR of about 23 dB, useful when testing receivers with very low noise figures. The 346C extends the frequency range to 26.5 GHz at the same 15 dB ENR as the 346A. The choice depends on your frequency range and the noise figure of the device under test — lower-noise devices need higher ENR sources for accurate measurement.
Why is the ENR calibration certificate so important for a noise source? +
The excess noise ratio (ENR) is the calibrated correction factor applied to every noise figure measurement. A noise source without a valid ENR certificate forces you to use the nominal tabulated value, which introduces measurement uncertainty of up to 0.5 dB or more. Noise figure measurements at ±0.1 dB accuracy require a traceable ENR certificate measured at each frequency point. We supply ENR data with every noise source we sell, and NIST-traceable ENR recalibration is available on request.
What frequency range is needed for 5G NR noise figure measurements? +
5G NR sub-6 GHz uses bands up to 6 GHz, making the Keysight N4000A (10 MHz to 18 GHz) or 346A sufficient. 5G NR mmWave (FR2) operates at 24.25–52.6 GHz, requiring the Keysight N4002A (10 MHz to 26.5 GHz) or a custom noise source for V-band. For radar receiver testing at 77 GHz (automotive) or 94 GHz (imaging), waveguide noise sources are required — contact us with the exact frequency requirement.
Can a noise source be used without a dedicated noise figure analyzer? +
Yes. A spectrum analyzer with a noise figure measurement application (like the Keysight N8975A, or an N9020A MXA with option NF2) can perform Y-factor measurements using any calibrated noise source. The spectrum analyzer must support the frequency range of the measurement. For general-purpose noise figure work at under 26 GHz, an N8975A noise figure analyzer paired with an N4001A source is the most common combination in used test labs.
What connector type do Keysight noise sources use? +
The standard 346 series uses an APC-7 connector, which requires an APC-7 to-N adapter for most modern test port connections. The N4000A series uses a 2.4 mm connector (to 26.5 GHz) and the N4002A also uses 2.4 mm. Adapters are not always included with used units — confirm connector and adapter requirements before ordering. We note the connector type and list any adapters present in each product listing.
Need ENR recalibration or a specific noise source model?
We offer NIST-traceable ENR calibration and can source specific noise source models on request.
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