Which models support variable internal modulation frequencies?

All three models (8648B, 8648C, and 8648D) offer standard internal modulation frequencies of 400 Hz and 1 kHz, which can be expanded to a range of 10 Hz to 20 kHz by adding Option 1E2.

Does the series include reverse power protection?

Yes, the 8648C specifically details built-in reverse power protection rated for up to 50 W at frequencies of 2 GHz or less, and up to 25 W for frequencies greater than 2 GHz.

Keysight Technologies (Agilent HP) 8648 Series Signal Generators

Q: What are the frequency limits of each model in the 8648 series?

The 8648B covers 9 kHz to 2 GHz, the 8648C covers 9 kHz to 3.2 GHz, and the 8648D covers 9 kHz to 4 GHz.

3 models with full specifications from Keysight Technologies (Agilent HP).

The Keysight Technologies (Agilent HP) 8648 Series comprises synthesized RF signal generators designed for manufacturing, semi-automated receiver testing, and general-purpose laboratory applications. These instruments share a core architecture designed for reliability and measurement repeatability, offering precise amplitude control, diverse analog modulation capabilities, and a standard GPIB interface. By offering different upper frequency limits across the family, the series allows technical buyers to select an instrument optimized for specific RF band requirements.

Frequency Resolution: 0.001 Hz
Modulation Types: AM, FM, Phase
System Impedance: 50 Ω
Communication Interface: GPIB (IEEE-488)

Models in this series

Model	Type	Dimensions (W×H×D)	Display	Frequency Resolution
8648C	Signal	330 x 133 x 368 mm	LCD	0.001 Hz
8648D	Signal	330 × 165 × 368	LCD	0.001 Hz
8648B	Signal	330 x 165 x 368 mm	LCD	0.001 Hz

Frequency Coverage and Selection

The primary differentiator within the 8648 series is the maximum frequency limit. The 8648B operates from 9 kHz to 2 GHz, the 8648C covers 9 kHz to 3.2 GHz, and the 8648D extends coverage up to 4 GHz. All three instruments share a high frequency resolution of 0.001 Hz, making them suitable for narrow-band receiver characterization across their respective bands.

Amplitude and Modulation Capabilities

Each generator in the series supports standard AM, FM, and Phase modulation. The 8648B also lists optional pulse modulation capabilities. Standard configurations provide internal modulation source frequencies of 400 Hz and 1 kHz, while Option 1E2 expands this capability to a variable 10 Hz to 20 kHz range across all three models.

For amplitude control, the series provides 0.1 dB resolution. The 8648B and 8648D specify an output power range of -136 dBm to +13 dBm. The 8648C features a solid-state electronic attenuator, an optional high-power configuration, and integrated reverse power protection rated up to 50 W for frequencies under 2 GHz (and 25 W for frequencies above 2 GHz).

Reference Oscillator and Stability Options

Frequency stability is governed by an internal 10 MHz reference oscillator. The standard configuration for the 8648B and 8648C provides a timebase aging rate of ±2 ppm/year.

For environments demanding greater precision, Option 1E5 lowers the aging rate to <0.1 ppm/year (specified as ±0.1 ppm/year on the 8648C). On the 8648B, Option 1E5 also improves the temperature stability to ±0.01 ppm from 0 °C to 50 °C, compared to the standard temperature stability of ±1 ppm.

Frequently asked questions

What are the frequency limits of each model in the 8648 series?: The 8648B covers 9 kHz to 2 GHz, the 8648C covers 9 kHz to 3.2 GHz, and the 8648D covers 9 kHz to 4 GHz.
Which models support variable internal modulation frequencies?: All three models (8648B, 8648C, and 8648D) offer standard internal modulation frequencies of 400 Hz and 1 kHz, which can be expanded to a range of 10 Hz to 20 kHz by adding Option 1E2.
Does the series include reverse power protection?: Yes, the 8648C specifically details built-in reverse power protection rated for up to 50 W at frequencies of 2 GHz or less, and up to 25 W for frequencies greater than 2 GHz.