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The MS2651B and MS2661B are fully synthesized portable spectrum analyzers covering a wide frequency range from 9 kHz to 3 GHz, built for analyzing the signals of radio communications systems, devices, and related equipment. They offer superior basic performance such as a high C/N ratio, low distortion, and high frequency and level accuracies, and they are easy to operate. Resolution bandwidth filters provide better selectivity than previously possible, and a large selection of options is available to handle a wide range of applications at reasonable cost. In standard configuration the instrument weighs only 11 kg and measures 320 (W) × 177 (H) × 351 (D) mm, making it well suited to both benchtop and field use.
The MS2661B is designed for the manufacture and installation of radio equipment and devices, while the MS2651B is meant for maintenance applications. A full range of "Measure" functions supports performance evaluation of radio equipment, including measurement of power levels, frequencies, adjacent channel power, channel power, occupied frequency bandwidth, burst average power, and mask and time template comparisons. The instruments are suited to measuring harmonic components and evaluating the non-linearity of high-power amplifiers, and to measuring adjacent channel power of both analog and digital radio communication equipment. With the appropriate options they extend to CATV maintenance, EMI measurement, filter frequency response and antenna impedance response measurement, return loss measurement, and TDMA-type radio equipment testing.
ValueTronics stocks and holds its own inventory in a 20,000-square-foot secure warehouse at 1675 Cambridge Drive in Elgin, Illinois. Holding equipment in-house allows our team to inspect and functionally verify every pre-owned unit before it ships, while new units leave the facility factory-sealed exactly as received. That combination of on-hand stock and in-house verification of used equipment is how we get the right instrument, in the right condition, into an engineer's hands quickly.
The MS2651B/2661B series consists of two fully synthesized portable spectrum analyzers that share the same 9 kHz to 3 GHz frequency range and a common feature set, including a synthesized local oscillator, a 1 Hz-resolution frequency counter, a 5.5-inch color TFT display, and standard RS-232C and GPIB interfaces. Both models are positioned around radio communications work, and high frequency/level accuracy and the 1 Hz-readout-resolution counter are common to both.
The two models are oriented to different tasks. The MS2661B is intended for the manufacture and installation of radio equipment and devices, with the capability to perform highly accurate measurement of adjacent channel power, harmonic spurious components, and in-band spurious components. The MS2651B is intended for maintenance applications, a good choice where there is no need to measure parameters such as adjacent channel power or harmonic distortions.
Each model in this series is listed as its own dedicated product page with pre-owned-condition-matched pricing. Choose the model that matches your measurement requirements, and the linked page reflects the current pre-owned availability and pricing for that specific configuration.
The MS2651B and MS2661B differ primarily in dynamic-range-related performance. Noise sideband is ≤ –90 dBc/Hz on the MS2651B versus ≤ –100 dBc/Hz on the MS2661B (both at 1 GHz, 10 kHz offset), and average noise level is ≤ –110 dBm on the MS2651B versus ≤ –115 dBm on the MS2661B (1 MHz to 1 GHz). The MS2661B also specifies lower harmonic and third-order intermodulation distortion. Refer to the comparison table that follows for the per-model figures.
Some options are model-specific. Narrow resolution bandwidth (Option 02), which adds 30 Hz, 100 Hz, and 300 Hz bandwidths, and DC coupled input (Option 19), which extends the lower frequency limit, are available on the MS2661B only. The QP detector is offered as Option 12 for the MS2661B and Option 13 for the MS2651B. Other options, such as the reference crystal oscillator, pre-amplifier, high-speed time domain sweep, trigger/gate circuit, and tracking generators, apply across both models.
| Model | Frequency Range | Noise Sideband (1 GHz, 10 kHz offset) | Average Noise Level (1 MHz to 1 GHz) |
|---|---|---|---|
| MS2661B | 9 kHz to 3 GHz | ≤–100 dBc/Hz | ≤–115 dBm |
| MS2651B | 9 kHz to 3 GHz | ≤–90 dBc/Hz | ≤–110 dBm |
Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.
| Specification | Value |
|---|---|
| Frequency | |
| Frequency range | 9 kHz to 3 GHz |
| Display frequency accuracy | ± (display frequency × reference frequency accuracy + span × span accuracy + 100 Hz) *Span: ≥10 kHz, after calibration |
| Marker frequency display accuracy | Normal: Same as display frequency accuracy, Delta: Same as frequency span accuracy |
| Frequency counter | Resolution: 1 Hz, 10 Hz, 100 Hz, 1 kHz; Accuracy: Display frequency × reference frequency accuracy ±1 LSD (at S/N: ≥20 dB) |
| Frequency span setting range | 0 Hz, 1 kHz to 3.1 GHz |
| Frequency span accuracy | ±2.5% (span: ≥10 kHz), ±5% (span: <10 kHz with Option 02) |
| Resolution bandwidth (RBW) (3 dB bandwidth) | 1 kHz, 3 kHz, 10 kHz, 30 kHz, 100 kHz, 300 kHz, 1 MHz, 5 MHz (manually settable, or automatically settable according to frequency span) *Option 02 (MS2661B only): 30 Hz, 100 Hz, and 300 Hz are added. |
| RBW selectivity (60 dB : 3 dB) | ≤10:1 (RBW: 1 to 300 kHz), ≤15:1 (RBW: 1, 5 MHz) |
| Video bandwidth (VBW) | 1 Hz to 3 MHz (1-3 sequence), OFF (manually settable, or automatically settable according to RBW) |
| Noise sideband | ≤–100 dBc/Hz (1 GHz, 10 kHz offset) |
| Residual FM | ≤20 Hzp-p/0.1 s (1 GHz, span: 0 Hz) |
| Frequency drift | ≤200 Hz/min (span: ≤10 kHz, sweep time: ≤100 s) *After 1-hour warm-up at constant ambient temperature |
| Reference oscillator frequency | 10 MHz |
| Reference oscillator aging rate | 2 × 10⁻⁶/year (typical); Option 01: 1 × 10⁻⁷/year, 2 × 10⁻⁸/day |
| Reference oscillator temperature characteristics | 1 × 10⁻⁵ (typical, 0° to 50°C); Option 01: ±5 × 10⁻⁸ (0° to 50°C, referenced to 25°C) |
| Amplitude | |
| Measurement range | Average noise level to +30 dBm |
| Maximum input level | +30 dBm (CW average power, RF ATT: ≥10 dB), ±50 Vdc |
| Average noise level | ≤–115 dBm (1 MHz to 1 GHz), ≤–115 dBm + f [GHz] dB (>1 GHz), ≤–114 dBm (1 MHz to 1 GHz, at Option 08 pre-amplifier installed), ≤–114 dBm + 1.5f [GHz] dB (>1 MHz, at Option 08 pre-amplifier installed) *RBW: 1 kHz, VBW: 1 Hz, RF ATT: 0 dB |
| Residual response | ≤–100 dBm (RF ATT: 0 dB, input: 50 Ω termination, 1 MHz to 3 GHz) |
| Total level accuracy | ±1.3 dB (100 kHz to 3 GHz) *Level measurement accuracy after calibration using internal calibration signal. Total level accuracy = Reference level accuracy (0 to –49.9 dBm) + frequency response + log linearity (0 to –20 dB) + calibration signal source accuracy |
| Setting range | Log scale: –100 to +30 dBm, Linear scale: 224 µV to 7.07 V |
| Unit | Log scale: dBm, dBµV, dBmV, V, dBµVemf, W, dBµV/m; Linear scale: V |
| Reference level accuracy | ±0.4 dB (–49.9 to 0 dBm), ±0.75 dB (–69.9 to –50 dBm, 0.1 to +30 dBm), ±1.5 dB (–80 to –70 dBm) *After calibration, at 100 MHz, 1 MHz span |
| RBW switching uncertainty | ±0.3 dB (1 kHz to 1 MHz), ±0.4 dB (5 MHz) *After calibration, referenced to RBW 3 kHz |
| Input attenuator (RF ATT) setting range | 0 to 70 dB (10 dB steps) *Manually settable, or automatically settable according to reference level |
| RF ATT switching uncertainty | ±0.3 dB (0 to 50 dB), ±1.0 dB (0 to 70 dB) *After calibration, frequency: 100 MHz, referenced to RF ATT: 10 dB |
| Frequency response | ±0.5 dB (100 kHz to 3 GHz, referenced to 100 MHz, RF ATT: 10 dB, 18° to 28°C); ±1.5 dB (9 to 100 kHz, referenced to 100 MHz, RF ATT: 10 dB, 18° to 28°C); ±1.0 dB (100 kHz to 3 GHz, referenced to 100 MHz, RF ATT: 10 to 50 dB) |
| Scale (10 div) | Log scale: 10, 5, 2, 1 dB/div; Linear scale: 10, 5, 2, 1%/div |
| Waveform display linearity (after calibration) | Log scale: ±0.4 dB (0 to –20 dB, RBW: ≤1 MHz), ±1.0 dB (0 to –70 dB, RBW: ≤100 kHz), ±1.5 dB (0 to –85 dB, RBW: ≤3 kHz), ±2.5 dB (0 to –90 dB, RBW: ≤3 kHz); Linear scale: ±4% (compared to reference level) |
| Marker level resolution | Log scale: 0.01 dB, Linear scale: 0.02% of reference level |
| 2nd harmonic distortion | ≤–60 dBc (10 to 200 MHz), ≤–75 dBc (0.2 to 1.5 GHz), ≤–80 dBc (0.8 to 1 GHz) *Mixer input: –30 dBm |
| Two signals 3rd order intermodulation distortion | ≤–70 dBc (10 to 100 MHz), ≤–80 dBc (0.1 to 3 GHz) *Frequency difference of two signals: ≥50 kHz, mixer input: –30 dBm |
| 1 dB gain compression | ≥–5 dBm (≥100 MHz, at mixer input) |
| 1 dB gain compression level to average noise level | >110 dB (0.1 to 1 GHz), >110 dB – f [GHz] dB (>1 GHz), >109 dB (0.1 to 1 GHz, at Option 08 pre-amplifier installed), >109 dB – 1.5f [GHz] (>1 GHz, at Option 08 pre-amplifier installed) |
| Maximum dynamic range — 2nd harmonic (RBW: 1 kHz) | >72.5 dB (10 to 200 MHz), >80 dB (200 to 500 MHz), >80 – f [GHz] dB (0.5 to 1.5 GHz), >82.5 – f [GHz] dB (0.8 to 1 GHz) |
| Maximum dynamic range — 3rd order intermodulation (RBW: 1 kHz) | >80 dB (10 to 100 MHz), >83.3 dB (0.1 to 1 GHz), >83.3 – (2/3)f [GHz] dB (1 to 3 GHz) |
| Sweep | |
| Sweep time setting range | 20 ms to 1000 s (manually settable, or automatically settable according to span, RBW, and VBW) |
| Sweep time accuracy | ±15% (20 ms to 100 s), ±45% (110 to 1000 s), ±1% (time domain sweep: digital zero span mode) |
| Sweep mode | Continuous, single |
| Time domain sweep mode | Analog zero span, digital zero span |
| Zone sweep | Sweeps only in frequency range indicated by zone marker |
| Tracking sweep | Sweeps while tracing peak points within zone marker (zone sweep also possible) |
| Number of data points | 501 |
| Detection mode | NORMAL: Simultaneously displays max. and min. points between sample points; POS PEAK: Displays max. point between sample points; NEG PEAK: Displays min. point between sample points; SAMPLE: Displays momentary value at sample points. Detection mode switching uncertainty: ±0.5 dB (at reference level) |
| Display | |
| Display | Color TFT-LCD, Size: 5.5", Number of colors: 17 (RGB, each 64-scale settable), intensity adjustment: 5 steps settable |
| Display functions | Trace A: Displays frequency spectrum; Trace B: Displays frequency spectrum; Trace Time: Displays time domain waveform at center frequency; Trace A/B: Displays Trace A and Trace B simultaneously (simultaneous sweep of same frequency, alternate sweep of independent frequencies); Trace A/BG: Displays frequency region to be observed (background) and object band (foreground); Trace A/Time: Displays frequency spectrum and time domain waveform at center frequency simultaneously at alternate sweep; Trace move/calculation: A→B, B→A, A↔B, A+B→A, A–B→A, A–B+DL→A |
| Storage functions | NORMAL, VIEW, MAX HOLD, MIN HOLD, AVERAGE, CUMULATIVE, OVER WRITE |
| FM demodulation waveform display — demodulation range | 2, 5, 10, 20, 50, 100, 200 kHz/div |
| FM demodulation waveform display — marker display accuracy | ±5% of full scale (referenced to center frequency, DC-coupled, RBW: 5 MHz, VBW: 1 Hz, CW) |
| FM demodulation waveform display — demodulation frequency response | DC (50 Hz at AC-coupled) to 100 kHz (Range: ≤20 kHz/div, VBW: OFF, at 3 dB bandwidth); DC (50 Hz at AC-coupled) to 500 kHz (Range: ≥50 kHz/div, VBW: OFF, at 3 dB bandwidth) *RBW: ≥100 kHz usable |
Important: Maximum input level: +30 dBm (CW average power, RF ATT ≥ 10 dB), ±50 Vdc.
Important: Narrow resolution bandwidth (Option 02), QP detector (Option 12) and DC coupled input (Option 19) are available on the MS2661B only.
Important: High-speed time domain sweep (Option 04) must be used with the trigger/gate circuit (Option 06).
Important: QP detector (Option 12) requires Option 02; DC coupled input (Option 19) requires Option 02; when Option 12 is installed, the Option 02 RBW 100 Hz 3 dB bandwidth is changed to 150 Hz (typical).
Important: GPIB and the Centronics interface (Option 10) cannot be installed simultaneously.
Important: 75 Ω input (Option 22) and 75 Ω tracking generator (Option 23): Options 12, 13, 19 and 20 cannot be installed simultaneously.
Important: RF connector input is rated up to +30 dBm; maximum DC input is ±50 V without Option 19 installed.
Recommended pairing: combine the tracking generator (Option 20) with an Anritsu reflection bridge such as the 60N50-1 for high-accuracy return loss measurement.
This pre-owned unit is inspected and functionally verified in-house before it ships and is backed by our pre-owned warranty. To confirm its exact condition, firmware revision, installed options, or included accessories for your application before ordering, contact our Test Architects.
ValueTronics supplies both new and used test and measurement equipment. New units ship factory-sealed, exactly as received from the manufacturer; every used unit is inspected and functionally verified in-house at our 20,000 sq ft secure facility in Elgin, Illinois before it ships. Our Test Architects can help you select the condition, calibration, and configuration that fit your application.
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.
Model No
Anritsu
Condition
Pre-Owned
Manufacturer
Anritsu
Spec_ana_freq
9 kHz to 3 GHz
30+ Years in Business
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On-site Lab
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