1Overview
The Model 855B is a purpose-built multi-channel source. It generates phase-coherent signals across two, three, or four channels in a compact 19-inch 1U chassis, and scales to eight channels in a 3U benchtop enclosure. The design targets synchronized outputs, where channels must hold a fixed phase relationship as frequency and power change.
The 855B carries the highest output power in the family at +25 dBm per channel, with very low phase noise and the industry’s lowest phase drift. Dedicated 3 GHz system reference I/O ports tie multiple units together, so a test bench can grow well past eight channels while staying phase-coherent.
2Key Features
- Highest output power in the family: up to +25 dBm per channel.
- Two, three, or four channels in 1U; up to eight channels in 3U.
- Very low phase noise and the industry’s lowest phase drift.
- Phase-coherent outputs with an optional phase-coherent switching mode.
- Ultra-fast switching down to 25 µs with option FS.
- Continuous frequency coverage with a wide power range per channel.
- Dedicated 3 GHz system reference I/O ports for multi-unit synchronization.
- Variable external clock reference input.
- USB, LAN, and GPIB interfaces with the SCPI 1999 command set.
3Frequency & Output Power
Frequency reach is set by variant, from 6 GHz up to 40 GHz with a settable ceiling of 42 GHz on the 855B-40. Output power is the highest in the family, and option PE4 extends the floor to -60 dBm with an electrical step attenuator.
| Parameter | Specification |
|---|---|
| 855B-6 | 300 kHz to 6 GHz (settable to 6.5 GHz) |
| 855B-12 | 300 kHz to 12 GHz (settable to 12.5 GHz) |
| 855B-20 | 300 kHz to 20 GHz |
| 855B-33 | 300 kHz to 33 GHz |
| 855B-40 | 300 kHz to 40 GHz (settable to 42 GHz) |
| Frequency resolution | 0.001 Hz |
| Output power range | -20 to +25 dBm (-60 to +25 dBm with PE4) |
| Channels | 2, 3, or 4 in 1U; 8 in 3U |
4Phase Noise & Spectral Purity
Phase noise is specified at a 1 GHz CW carrier. The standard instrument reaches -87 dBc/Hz at 10 Hz, and option LN improves close-in performance to -100 dBc/Hz at the same offset.
| Offset from carrier (1 GHz CW) | Phase noise |
|---|---|
| 10 Hz | -87 dBc/Hz (-100 dBc/Hz with option LN) |
| 1 kHz | -130 dBc/Hz |
| 20 kHz | -145 dBc/Hz |
| 100 kHz | -150 dBc/Hz |
5Modulation
The 855B generates pulse modulation as standard. The MOD option adds analog amplitude, frequency, and phase modulation. Vector modulation is not described on the product page.
| Mode | Availability |
|---|---|
| Pulse | Standard |
| AM, FM, PM (analog) | Option MOD |
| Vector modulation | (verify) |
6Frequency Switching & Sweep
In sweep mode the 855B switches in 500 µs, and option FS brings switching down to 25 µs per channel. Sweep modes cover list, frequency, and power. Option PHS adds phase-coherent switching, and requires the LN or LN plus option.
| Parameter | Specification |
|---|---|
| Switching speed (sweep mode) | 500 µs standard; 25 µs with option FS |
| Sweep / list modes | List, Frequency, Power |
| Phase-coherent switching | Option PHS (requires LN or LN plus) |
| External reference | Variable external clock input; option VREF 1 MHz to 250 MHz |
7Specifications
| Parameter | Specification |
|---|---|
| Frequency range | 855B-6: 300 kHz to 6 GHz (set 6.5); 855B-12: 300 kHz to 12 GHz (set 12.5); 855B-20: 300 kHz to 20 GHz; 855B-33: 300 kHz to 33 GHz; 855B-40: 300 kHz to 40 GHz (set 42) |
| Frequency resolution | 0.001 Hz |
| Number of channels | 2, 3, or 4 in 1U 19-inch rack; 8 in 3U benchtop |
| Output power range | -20 to +25 dBm (-60 to +25 dBm with PE4) |
| Phase noise (1 GHz CW) | 10 Hz: -87 dBc/Hz (-100 with LN); 1 kHz: -130; 20 kHz: -145; 100 kHz: -150 dBc/Hz |
| Harmonics / spurious | (verify, see datasheet PDF) |
| Switching speed (sweep mode) | 500 µs (25 µs with option FS) |
| Modulation | Pulse (standard); AM, FM, PM (option MOD) |
| Vector modulation | (verify) |
| Sweeps / list | List, Frequency, Power |
| Interfaces | Ethernet and USB; GPIB optional; SCPI 1999 |
| Form factor | 19-inch 1U (2, 3, 4 ch); 19-inch 3U (8 ch) |
| Dimensions (1U) | 19 × 18.25 × 1.75 in [483 × 463 × 44 mm] |
| Dimensions (3U) | 19 × 12.25 × 5.25 in [483 × 311 × 133 mm] |
| Weight | 2 ch: 13 lbs (5.9 kg); 4 ch: 17 lbs (7.7 kg); 8 ch: 22 lbs (10 kg) |
| Shipping dimensions / weight | 23 × 23 × 19 in; 19 lbs |
| Power requirements | (verify) |
8Interfaces & Form Factor
The 855B is controlled through Ethernet and USB, with GPIB available as an option, all using the SCPI 1999 command set. Dedicated 3 GHz system reference I/O ports synchronize multiple units, so phase-coherent test setups can scale past a single chassis.
Two, three, or four channels fit a compact 19-inch 1U enclosure. Eight channels occupy a 19-inch 3U benchtop enclosure. A high-isolation chassis is available with option HI.
9Options & Configurations
| Option | Description |
|---|---|
| -LN | Enhanced close-in phase noise |
| -LN plus | Low noise with improved long-term frequency stability |
| -PHS | Phase-coherent switching (requires LN or LN plus) |
| -FS | Fast switching (per channel) |
| -MOD | Analog modulation (AM, FM, PM) |
| -VREF | Variable external reference input (1 MHz to 250 MHz) |
| -VF | Varied frequencies: different frequency ranges per output |
| -PE4.20 | Power extension to -60 dBm (electrical step attenuator) |
| -HI | High-isolation chassis |
| -GPIB | GPIB communication port |
| -FLASH | MicroSD card slot |
10Applications
- Radar simulation and phased-array antenna or beamforming test.
- Quantum computing.
- High-volume automated testing.
- Electronic warfare.
- Satellite communications R&D.
11Ordering
Specify the frequency variant (855B-6 through 855B-40), channel count, chassis size, and options when requesting a quote. For configuration help, pricing, or a demonstration, contact Berkeley Nucleonics.
| Contact | Detail |
|---|---|
| info@berkeleynucleonics.com | |
| Phone | 800-234-7858 |
| Quote / demo | berkeleynucleonics.com/get-quote |