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The U3641/3641N is a 3 GHz synthesized spectrum analyzer built specifically for field installation and maintenance work. A lightweight, compact body paired with a three-way power supply — including battery operation — lets it travel to the work site, while a synthesized local oscillator delivers high-precision, high-stability measurements. The U3641, U3641N, and U3641PHS are portable analyzers suited to maintenance across CATV and PHS/PDC applications.
These analyzers are intended for logistically wide-ranging field measurement such as installation and maintenance. The 50 µs zero-span sweep makes it possible to characterize the rising and falling edges of burst signals and to measure power during on and off periods, supporting observation of TDMA waveforms for GSM, IS-136, PDC, and PHS with magnified display of burst transitions. CATV and PHS/PDC maintenance are among the listed field uses.
ValueTronics stocks and holds its own test-and-measurement inventory in a 20,000 sq ft secure warehouse at 1675 Cambridge Drive in Elgin, Illinois.
The U3641 series is a family of three portable, 3 GHz synthesized spectrum analyzers that share the same field-oriented design: a lightweight, compact body, a three-way power supply with battery operation, and a built-in preamplifier for high-sensitivity field measurement. The models are the U3641, the U3641N, and the U3641PHS.
Across the family, all three models cover 9 kHz to 3 GHz with a 100 dB display dynamic range and the same synthesized-oscillator stability. They differ primarily in RF input impedance and in the PHS-specific demodulation capability of the U3641PHS, with option availability also varying by model.
Each pre-owned model below is its own dedicated product page with condition-matched pricing. Select the model that matches your input-impedance and demodulation requirements, then choose the listing for the condition you need.
The clearest difference is RF input impedance: the U3641 presents a 50 Ω N-type input, while the U3641N presents a 75 Ω input and ships with the corresponding NC-BNC and N-C15 connector adaptors. The U3641PHS uses a 50 Ω input and adds a PHS-ID demodulator function — a TDMA-TDD, π/4 DQPSK receiver whose logic control channel configuration conforms to RCR STD-28 — for ID discrimination by PHS control channel demodulation.
Option coverage also varies, as the comparison table shows. The controller (OPT.15), narrow-RBW (OPT.26), and tracking generator (OPT.74) options apply across all three models, while the high-stability reference (OPT.20), TV demodulation (OPT.72), and channel input setting (OPT.78) options are offered on the U3641 and U3641N. Refer to the table below for the per-model option and impedance details.
| Model | Frequency Range | Input Impedance | Display Dynamic Range |
|---|---|---|---|
| U3641N | 9 kHz to 3 GHz | 75 Ω | 100 dB |
| U3641 | 9 kHz to 3 GHz | 50 Ω | 100 dB |
| U3641PHS | 9 kHz to 3 GHz | 50 Ω | 100 dB |
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 (Start, Stop, CF, Marker) |
| Frequency Readout Accuracy | ± (freq readout × freq ref error + 5% × span + 15% × RBW + 10 Hz) |
| Count Frequency Marker Resolution | 1 Hz to 1 kHz |
| Count Frequency Marker Accuracy | ± (marker freq × freq reference accuracy + 1 LSD ± 5 Hz) (S/N ≥ 25 dB, RBW ≥ 3 kHz, 1 kHz ≤ SPAN ≤ 200 MHz) |
| Frequency Reference Accuracy | ± 2 × 10⁻⁶/year; ± 1 × 10⁻⁵ (at 0 to 50 °C) |
| Frequency Span Range | 1 kHz to 3.2 GHz, 0 Hz (ZERO span) |
| Frequency Span Accuracy | ≤ ± 5% (SPAN) |
| Residual FM | ≤ 60 Hz p-p/100 ms (ZERO span) |
| Frequency Drift | < 150 Hz/min (SPAN ≤ 10 kHz) |
| Noise Sidebands | ≤ -105 dBc at 20 kHz offset; ≤ -100 dBc at 10 kHz offset |
| Resolution Bandwidth Range (3 dB) | 1 kHz to 3 MHz (1-3 sequence); 100 Hz, 300 Hz (OPT.26) |
| Resolution Bandwidth Accuracy | ≤ ± 20% (1 kHz to 1 MHz); ≤ ± 25% (3 MHz) |
| Resolution Bandwidth Selectivity | < 15:1 (60 dB : 3 dB, RBW 1 kHz to 3 MHz) |
| Video Bandwidth | 10 Hz to 3 MHz (1-3 step) |
| Sweep | |
| Sweep Time | 50 ms to 1000 s; 50 µs to 1000 s (ZERO span) |
| Sweep Time Accuracy | ≤ ± 5% |
| Trigger Mode | FREE RUN, SINGLE, VIDEO, EXT, TV |
| Amplitude | |
| Amplitude Range | U3641/U3641PHS: +20 dBm to displayed average noise level; U3641N: +130 dBµV to displayed average noise level |
| Maximum Input Level (Preamplifier OFF, Input atten ≥ 10 dB) | U3641/U3641PHS: +27 dBm; U3641N: +134 dBµV; ± 50 V DC max. |
| Maximum Input Level (Preamplifier ON, Input atten ≥ 10 dB) | U3641/U3641PHS: +13 dBm; U3641N: +120 dBµV |
| Display Range (Log) | 10 × 10 div (10, 5, 2, 1 dB/div) |
| Display Range (Linear) | 10% of reference level/div (RBW ≥ 3 kHz) |
| Reference Level Range (Preamplifier OFF, Log) | U3641/U3641PHS: -64 to +40 dBm (0.1 dB step); U3641N: +46 dBµV to +150 dBµV |
| Reference Level Range (Preamplifier OFF, Linear) | U3641/U3641PHS: +141.1 µV to +22.36 V; U3641N: +198.4 µV to +31.44 V |
| Reference Level Range (Preamplifier ON, Log) | U3641/U3641PHS: -89 to -25 dBm (0.1 dB step); U3641N: +21 dBµV to +85 dBµV |
| Reference Level Range (Preamplifier ON, Linear) | U3641/U3641PHS: +7.934 µV to +12.57 mV; U3641N: +11.16 µV to +17.68 mV |
| Input Attenuator Range | 0 to 50 dB (10 dB step) |
| Dynamic Range | |
| Displayed Average Noise Level (Preamplifier OFF) | U3641/U3641PHS: -117 dBm + 2.7f (GHz) dB; U3641N: -8 dBµV + 2.7f (GHz) dB (RBW 1 kHz, VBW 10 Hz, Input atten 0 dB, f ≥ 1 MHz) |
| Displayed Average Noise Level (Preamplifier ON) | U3641/U3641PHS: -135 dBm + 4.3f (GHz) dB; U3641N: -26 dBµV + 4.3f (GHz) dB |
| Gain Compression (1 dB, Preamplifier OFF, mixer input level, f ≥ 10 MHz) | U3641/U3641PHS: > -10 dBm; U3641N: > +100 dBµV |
| Gain Compression (1 dB, Preamplifier ON, RF input level, f ≥ 10 MHz, ATT = 0) | U3641/U3641PHS: > -40 dBm; U3641N: > +70 dBµV |
| Second Harmonic Distortion (Input atten 0 dB, f ≥ 10 MHz) | U3641/U3641PHS: ≤ -70 dB (-30 dBm input); U3641N: ≤ -70 dB (+78 dBµV input) |
| Third Order Intermodulation Distortion (Input atten 0 dB, f ≥ 10 MHz) | U3641/U3641PHS: ≤ -70 dB (-30 dBm input); U3641N: ≤ -70 dB (+78 dBµV input) |
| Residual Responses (Preamplifier OFF, Input atten 0 dB, f ≥ 10 MHz) | U3641/U3641PHS: ≤ -100 dBm, 50 Ω; U3641N: ≤ +10 dBµV, 75 Ω |
| Residual Responses (Preamplifier ON) | U3641/U3641PHS: ≤ -105 dBm, 50 Ω; U3641N: ≤ +5 dBµV, 75 Ω |
| Amplitude Accuracy | |
| Resolution Bandwidth Switching Uncertainty | ≤ ± 1.0 dB at RBW 3 MHz as reference (after automatic calibration; 10 dB reference, 20 to 50 dB setting) |
| Frequency Response (Preamplifier OFF) | U3641/U3641PHS: ≤ ± 1 dB (100 kHz to 2.7 GHz), ≤ ± 2 dB (9 kHz to 3.0 GHz); U3641N: ≤ ± 1 dB (100 kHz to 2.2 GHz) |
| Frequency Response (Preamplifier ON) | U3641/U3641PHS: ≤ ± 1 dB (100 kHz to 2.7 GHz), ≤ ± 2 dB (9 kHz to 3.0 GHz); U3641N: ≤ ± 1 dB (100 kHz to 2.2 GHz) (At input attenuator 10 dB, 20 °C to 30 °C, referenced to 30 MHz and after calibration) |
| Calibration Signal Accuracy | U3641/U3641PHS: -20 dBm ± 0.3 dB; U3641N: +90.5 dBµV ± 0.3 dB |
| Input Attenuator Switching Accuracy | U3641/U3641PHS: ≤ ± 0.5 dB (after automatic calibration); U3641N: ≤ ± 1.0 dB (100 kHz to 2.7 GHz), ≤ ± 1.5 dB (9 kHz to 3.0 GHz), ≤ ± 1.0 dB (100 kHz to 2.2 GHz) |
| IF Gain Uncertainty | ≤ ± 1.5 dB/90 dB |
| Scale Fidelity (Log) | ≤ ± 1 dB/10 dB; ≤ ± 0.2 dB/1 dB |
| Scale Fidelity (Linear) | ≤ ± 5% of reference level (RBW ≥ 3 kHz) |
| Demodulation | |
| Spectrum Demodulation Modulation Type | AM and FM (FM is at RBW ≥ 3 kHz) |
| Audio Output | Speaker and phone jack with volume control |
| RF Input | |
| Connector | N type jack |
| Impedance | U3641: 50 Ω (nominal); U3641N: 75 Ω (nominal) |
| VSWR (Preamplifier OFF) | ≤ 1.5 : 1 (100 kHz to 2 GHz); ≤ 2 : 1 (9 kHz to 3.0 GHz (U3641) / 2.2 GHz (U3641N)) (Input atten ≥ 10 to 50 dB) |
| VSWR (Preamplifier ON) | ≤ 2.5 : 1 (10 MHz to 3.0 GHz (U3641) / 2.2 GHz (U3641N)) |
| Inputs & Outputs | |
| 10 MHz Reference Input | BNC jack, rear panel; 500 Ω (nominal); Input Range 0 to +16 dBm |
| Video Output | BNC jack, rear panel; 75 Ω (nominal), AC coupled; approx. 1 Vp-p, 75 Ω (composite video signal) |
| External Trigger Input | BNC jack, rear panel; 10 kΩ (nominal), DC coupled; TTL level |
| Gate Input | BNC jack, rear panel; 10 kΩ (nominal); sweep stop during TTL low level, sweep continue during TTL high level |
| Phone Output | Subminiature monophonic jack, front panel; power output 0.2 W, 8 Ω (nominal) |
| GPIB Interface | IEEE-488 bus connector; Plotter: HP-GL commands (682-XA); Printer: PCL commands |
| RS232 | D-SUB 9 pin, rear panel |
| Power Input / Battery Mounter | AC/DC adapter (A08364) or battery (option) |
| General Specifications | |
| Operating Temperature | 0 to 50 °C, humidity 85% or less |
| Non-operating Temperature | -20 to +60 °C |
| Power Supply – External DC Input | Connector XLR 4 pin; Voltage +10 to +16 V |
| Power Supply – AC Input | Automatically selects between 100 VAC and 200 VAC; 100 VAC operation: 100 to 120 V, 50/60 Hz; 220 VAC operation: 220 to 240 V, 50/60 Hz |
Important: OPT.20 (high-stability reference) and OPT.70 cannot be installed at the same time; likewise, OPT.72 (TV demodulation) and OPT.70 cannot be installed at the same time.
Important: OPT.78 is included in OPT.72.
Important: The GSM/DCS1800/DCS1900 application software packages are available only in the manual (master) mode and require the controller option (OPT.15) for operation.
Important: The battery pack (PROPAC14BATT) is an option and is not included with the standard unit; the U3641/3641N also operate on 100/200 VAC or +10 to +16 V DC. A full charge provides approximately 1.5 hours of continuous operation with a rapid 1 hour charging time.
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
Advantest
Condition
Pre-Owned
Manufacturer
Advantest
Spec_ana_freq
9 kHz to 3 GHz
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