# Agilent 8644B 1 GHz High Performance RF Signal Generator (Pre-Owned)

# Agilent 8644B 1 GHz High Performance RF Signal Generator (Pre-Owned)

## Key Features At A Glance

-   Frequency coverage from 252 kHz to 1030 MHz (8644B), 100 kHz to 3000 MHz (8664A), and 100 kHz to 6000 MHz (8665B)
-   0.01 Hz frequency resolution across the family with standard timebase accuracy of 0.375 x 10⁻⁶ times carrier in Hz
-   AM, FM, and phase modulation standard; pulse modulation available as an option on 8664A and 8665B (Option 008)
-   Dual internal modulation sources supporting sine, triangle, sawtooth, square, and white Gaussian noise waveforms for two-tone testing
-   GPIB (IEEE 488.2-1987) remote programming with HP-SL control language across all functions except power
-   High-stability oven-controlled timebase standard; recommended three-year calibration interval (MTBC)
-   Surface-mount construction with built-in self-diagnostics and calibration for reduced downtime
-   Multiple output, modulation, and leakage options including reduced leakage (Option 010) and high-stability timebase with EFC (Option 001)

The Agilent 8644B, 8664A, and 8665B are high performance RF signal generators positioned as the spectral-purity and frequency-coverage flagships of the Agilent synthesized signal generator line. The 8644B covers 252 kHz to 1030 MHz (extendable to 2060 MHz with Option 002) and is specified for lowest SSB phase noise, lowest spurious, highest output power, and lowest residual FM in the family. The 8664A extends coverage to 3000 MHz, and the 8665B extends coverage to 6000 MHz, with both higher-frequency models offering AM, wideband FM, and optional high-performance pulse modulation.

The datasheet identifies specific applications across the three instruments. For RF communications, the 8644B is positioned for out-of-channel receiver testing on receivers with ≥ 90 dB selectivity and spurious immunity of ≥ 85 dB, while the 8664A serves the same application class with Option 004 and the 8665B extends that performance to 6 GHz. For component test, the 8644B is identified for mixer testing where highest output power is needed, the 8664A for clock-source applications driving high-speed digital components, and the 8665B for response testing requiring output level accuracy to 6 GHz. For radar and EW test, all three models provide full functionality, with the 8664A and 8665B offering optional pulse modulation with internal delay and width adjust.

## Brand Heritage

Hewlett-Packard's test and measurement business was spun out as Agilent Technologies in 1999, and the electronic measurement division was further separated as Keysight Technologies in 2014. Instruments originally branded HP and later Agilent — including the 8644B, 8664A, and 8665B signal generators — trace their direct support and calibration lineage through Keysight today.

## Compare Other Models in This Series

The 8644B, 8664A, and 8665B form Agilent's high performance RF signal generator family, sharing the same synthesized architecture, the same internal modulation source design, the same GPIB programming interface, and the same surface-mount construction with three-year recommended calibration interval. They differ primarily in upper frequency coverage and in the specific spectral-purity and modulation tradeoffs optimized for different application classes.

The 8644B is the spectral-purity flagship, covering 252 kHz to 1030 MHz (or 2060 MHz with Option 002) and specified for the lowest SSB phase noise, lowest spurious, highest output power, and lowest residual FM in the family. The 8664A extends coverage to 3000 MHz with wideband FM rates suitable for many digital systems, and the 8665B extends the same architecture to 6000 MHz for applications requiring coverage of the upper microwave bands.

Each pre-owned model in this family is listed on its own dedicated product page with condition-matched pricing and inventory. Selecting the model below opens that page so you can review the specific configuration, options installed, and current availability.

Frequency range is the primary differentiator: 0.252 to 1030 MHz on the 8644B (extendable to 2060 MHz with Option 002), 0.1 to 3000 MHz on the 8664A, and 0.1 to 6000 MHz on the 8665B. SSB phase noise specifications also differ — at a 1 GHz carrier and 20 kHz offset, the 8644B is specified at –136 dBc/Hz (typical –142 dBc/Hz), the 8664A and 8665B at –117 dBc/Hz standard or –134 dBc/Hz with Option 004 in the 515 to 1030 MHz band. The 8644B also offers a built-in 2 GHz frequency counter (Option 011) and specified VOR/ILS signal simulation (Option 009) not available on the 8664A or 8665B.

Output level range is +16 to –137 dBm on the 8644B and +13 to –139.9 dBm on the 8664A and 8665B. Pulse modulation is standard on the 8644B with > 35 dB on/off ratio and < 100 ns rise/fall time, while on the 8664A and 8665B it is offered as Option 008 with > 80 dB on/off ratio, < 5 ns rise/fall time, and a built-in pulse generator with variable delay and width from 50 ns to 999 ms. The comparison table below summarizes the headline specifications side by side.

Model

Frequency Range

Max Output Power

SSB Phase Noise @ 1 GHz, 20 kHz Offset

**8644B**

0.252 MHz to 1030 MHz (to 2060 MHz with Option 002)

+16 dBm (+13 dBm with Option 002/005)

\-136 dBc/Hz (515 to 1030 MHz); -142 typical

8664A

0.1 MHz to 3000 MHz

+13 dBm (+9 dBm with Option 008)

\-117 dBc/Hz standard, -134 dBc/Hz with Option 004 (515 to 1030 MHz)

8665B

0.1 MHz to 6000 MHz

+13 dBm (+9 dBm with Option 008)

\-117 dBc/Hz standard, -134 dBc/Hz with Option 004 (515 to 1030 MHz)

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

## Product Core & Specifications

Specification

8644B

8664A, 8665B

Frequency

Range

0.252 to 1030 MHz; 0.252 to 2060 MHz with Option 8644B-002

0.1 to 3000 MHz (8664A); 0.1 to 6000 MHz (8665B)

Resolution

0.01 Hz

0.01 Hz

Accuracy (std. timebase, < 1 year of calibration)

0.375 x 10\-6 times carrier in Hz

0.375 x 10\-6 times carrier in Hz

Switching speed (typical, within 100 Hz)

< 350 ms

< 50 ms (within 0.33 ppm); < 100 ms with Option 8664A-004 or 8665B-004

Spectral Purity — SSB Phase Noise (dBc/Hz at 20 kHz offset)

4120 to 6000 MHz

N/A

Standard: -105; Option 004: -116

3000 to 4120 MHz

N/A

Standard: -105; Option 004: -122

2060 to 3000 MHz

N/A

Standard: -111; Option 004: -122

1030 to 2060 MHz

\-130 (Option 8644B-002)

Standard: -111; Option 004: -128

515 to 1030 MHz

\-136 (-142 typical)

Standard: -117; Option 004: -134

257.5 to 515 MHz

\-142

Standard: -122; Option 004: -139

128.5 to 257.5 MHz

\-145

N/A

0.25 to 128.5 MHz

\-145

N/A

187.5 to 257.5 MHz (8664A, 8665B)

N/A

Standard: -128; Option 004: -144

0.1 to 187.5 MHz (8664A, 8665B)

N/A

Standard: -117; Option 004: -131

Nonharmonics

< -105 dBc, > 10 kHz offset, 0.252 to 1030 MHz; < -100 dBc, > 10 kHz offset, 1030 to 2060 MHz

< -100 dBc, > 10 kHz offset, 187.5 to 2060 MHz; < -90 dBc, > 10 kHz offset, 2060 to 6000 MHz, 0.1 to 187.5 MHz

Harmonics

< -25 dBc, output ≤ +10 dBm

< -30 dBc, output ≤ +10 dBm

Subharmonics

None, 0.252 to 515 MHz; < -52 dBc, 515 to 1030 MHz; < -40 dBc, 1030 to 2060 MHz

< -75 dBc, 0.1 to 1500 MHz; < -40 dBc, 1500 to 3000 MHz; < -50 dBc, 3000 to 6000 MHz

Residual AM (0.3 to 3 kHz post det. BW)

< 0.01% AM rms

< 0.04% AM rms

SSB AM noise floor (offsets > 100 kHz)

< -157 dBc/Hz, 10 dBm, < 1030 MHz; < -150 dBc/Hz, 10 dBm, < 2060 MHz

< -137 dBc/Hz, 13 dBm, < 187.5 MHz; < -150 dBc/Hz, 13 dBm, > 187.5 MHz

Internal Reference Oscillator

Stability type

Standard high stability

Option 001 high stability with EFC

Aging

+1.5 x 10\-8/day after 10 days

±3 x 10\-10/day after 10 days

Temperature

+7 x 10\-10, 0 to 55 °C

±6 x 10\-10, to 55 °C

Line voltage

±2 x 10\-10, (+5%, -10%)

±1 x 10\-10, ±10%

Reference output

10 MHz, > 0.15 Vrms into 50 Ω

10 MHz, > 1 Vrms into 50 Ω

External reference input

Accepts 10 MHz ±5 ppm and a level range of 0.5 V to 2 Vrms into 50 Ω

Output Level

Range

+16 to -137 dBm; +13 dBm with Option 8644B-002/005

+13 to -139.9 dBm; +9 dBm with Option 8664A-008 or 8665B-008

Resolution

0.01 dB

0.01 dB

Absolute accuracy

±1 dB, output ≥ -127 dBm; ±3 dB, output < -127 dBm

±1 dB, output ≥ -119.9 dBm, 1 to 1000 MHz; ±1.5 dB, 1000 to 3000 MHz; ±2 dB, 3000 to 6000 MHz, < 1 MHz; ±3 dB, output ≥ -129.9 dBm

Reverse power protection

50 watts

25 watts (1 watt on 8665B), 0.1 to 2060 MHz; 1 watt, > 2060 MHz

Third order intermod (frequencies < 1300 MHz, two signals at +8 dBm, 25 kHz apart)

< -50 dBc

< -47 dBc

Overrange

Typically 2 dB

Typically 2 dB

Switching speed (typical)

< 50 ms

< 50 ms

SWR (≥ 0 dBm)

< 2.2:1

< 1.75:1 (< 3000 MHz); < 2.0:1 (≥ 3000 MHz)

SWR (< 0 dBm)

< 1.5:1

< 1.5:1 (< 3000 MHz); < 1.75:1 (≥ 3000 MHz)

Output impedance

50 Ω

50 Ω

Amplitude Modulation

Depth

0 to 100%, output ≤ +7 dBm

0 to 100%, output ≤ +7 dBm

Resolution

0.1%

0.1%

Bandwidth (3 dB)

dc to > 100 kHz, > 128 MHz

dc to > 10 kHz for > 10 MHz

Accuracy at 1 kHz rate

±(7% of setting +1%) up to 80% depth

±(6% of setting +1%) up to 90% depth

Distortion (30% depth, 1 kHz rate)

< 3%; < 4% (8644B-002)

< 4%

Incidental phase modulation (at 30% depth, 1 kHz rate)

< 0.2 radians peak

< 0.2 radians peak, ≤ 2000 MHz; < 0.2 radians peak, > 2000 MHz

Frequency Modulation

Maximum peak deviation

20 MHz/200 kHz, > 1030 MHz; 10 MHz/100 kHz, > 515 MHz; 5 MHz/50 kHz, > 257.5 MHz; 2.5 MHz/25 kHz, > 128.5 MHz; 1.25 MHz/12.5 kHz, > 64 MHz; 62.5 kHz/6.25 kHz, > 32 MHz

20 MHz, 3000 to 6000 MHz; 10 MHz, 1500 to 3000 MHz; 5 MHz, 750 to 1500 MHz; 2.5 MHz, 375 to 750 MHz; 1.25 MHz, 187.5 to 375 MHz; 5 MHz, < 187.5 MHz

Resolution

2.5% of setting

2.5% of setting

Bandwidth (3 dB)

dc to 100 kHz

dc to 800 kHz

Carrier accuracy in FM

±0.5% of setting

±0.6% of setting

External input impedance

600 Ω

600 Ω

**Important:** Reverse power protection: 50 watts on the 8644B; 25 watts from 0.1 to 2060 MHz and 1 watt above 2060 MHz on the 8664A and 8665B (1 watt on 8665B per ordering note).**Important:** Recommended calibration interval is three years (MTBC).**Important:** Option 8644B-005 (Electronic Attenuator) is not available with Option 8644B-002.**Important:** Option 004 (Low Noise Option) is not applicable to the 8644B.**Important:** Option 010 (Reduced Leakage Configuration) increases instrument depth by 35 mm (1.4 in.).

## About this used unit

-   Warranty included
-   Functional verification included
-   Standard Calibration Upgrade Options: No Calibration Required, NIST Traceable, Z540.1 or ISO 17025 with Data, Z540.3 Guardbanding with Data.
-   Note that unnecessary accessories may not be included (contact Test Architect to confirm).

**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.**

## Details

- **Price:** 0.0 USD - 3975.0 USD
- **Vendor:** Agilent
- **Type:** Rf Gen
- **Tags:** Agilent, Agilent Keysight, Manufacturers, product_manual_group_1, Product_used, RF, Signal Generators, Updated Item Review

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| No Option / None | 0.00 USD | In stock |
| No Option / NIST Traceable | 0.00 USD | In stock |
| No Option / NIST Traceable with Full Data | 0.00 USD | In stock |
| No Option / ISO IEC 17025 Accredited | 0.00 USD | In stock |
| 005 / None | 2995.00 USD | In stock |
| 005 / NIST Traceable | 3625.00 USD | In stock |
| 005 / NIST Traceable with Full Data | 3765.00 USD | In stock |
| 005 / ISO IEC 17025 Accredited | 3975.00 USD | In stock |

## Images

- 8644B Agilent RF Generator

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> Source: [ValueTronics](https://valuetronics.com/products/8644b-agilent-rf-generator-used)
> Updated: 2026-05-30