In this episode Shahriar reviews the Rohde & Schwarz ZNLE 1MHz – 6GHz Vector Network Analyzer. The ZNLE is the economy model of the ZNL 3-in-1 instrument. The R&S ZNLE is a two-port vector network analyzer that can be used for bidirectional measurements of S-parameters S11, S21, S12 and S22 on passive components. Ordering the RR&S ZNLE requires only two decisions: the frequency range and whether or not you need a GPIB interface. The analyzer is available with a frequency range of 1 MHz to 3 GHz (R&S ZNLE3) or 1 MHz to 6 GHz (R&S ZNLE6). The optional GPIB interface lets you connect a controller to remotely control the R&S ZNLE. As a standalone instrument, the R&S ZNLE does not require an external PC to configure the setup. You can start measuring immediately after you switch on the instrument.
The review is organized as follows:
01:12 – Model comparison and overview.
02:24 – Instrument overview and design.
06:29 – Brief teardown and internal construction.
09:31 – Electronic Calibration Unit and auto-cal procedure.
17:39 – Measurement and characterization of a tunable microwave filter.
30:47 – Measurement of a tunable phase shifter.
33:16 – Analysis and measurement of a trice coupled quad-patch antenna module.
39:10 – Performance and characterization of an ZNLE internal synthesizer.
46:31 – Mixed-mode S-Parameter measurements using the ZNLE.
49:15 – Extreme dynamic range measurements using a 0.1dB step electromechanical attenuator.
1:02:48 – Overview of additional functions.
1:04:26 – Concluding remarks.
In this episode Shahriar reviews the Rohde & Shwarz RTB2004 10-Bit oscilloscope. With its high-resolution touch-screen, intuitive and capable GUI as well as excellent analog/digital performance this scope competes very well against other 2000 series instruments from Tektronix and Keysight. This extensive review includes instrument teardown, overview and dedicated experiments as follows:
01:17 – Model comparison and R&S scope lineup.
02:20 – Front panel, rear panel and overview.
05:01 – Instrument teardown and analysis.
13:37 – Power on and basic functions including intensity grading, XY mode.
26:29 – Multi-tone behavior, FFT and ADC performance.
33:17 – Experiment with ambient light follower: Analog and RS232 digital serial capture, triggering and analysis.
48:03 – Experiment with external DAC: Analog and I2C data capture and search using remote web interface.
57:19 – Built-in arbitrary waveform generator behavior and performance.
In this episode Shahriar repairs a BK Precision 9185 600V linear power supply. The instrument is missing a power connector and therefore cannot be powered on. To be cautious, the unit is disassembled first before being retrofitted with a new connector. The teardown reveals damaged resistors at the back of the main power supply PCB. The damage points to a defective high-voltage MOSFET. This transistor is one of six devices in parallel. The impacted components are all replaced before the unit is retrofitted with a new power connector.
After power on the unit is verified for proper operation. Using a Keithley DMM7510, the power supply is calibrated and is ready for future experiments.
In this episode Shahriar repairs an Agilent 8562E 13.2GHz spectrum analyzer which does not power on. Upon pressing the power button the power LED briefly flashes and turns off. Teardown of the unit reveals a compact instrument where the power supply is rather difficult to reach.
The power supply block diagram shows various internal block functions which include startup, DC-DC converter and output regulation stages. In order to diagnose the instrument, the CMOS driver ICs were removed and swamped. An error during the installation of the gate drivers caused a cascade failure of the supply components! After replacing all the affected components as well as the DC-DC converter PWM controller IC, the power supply is repaired.
After powering on the unit it becomes clear that there are several internal self-test and alignment errors. The errors point to YIG oscillator failure. The YIG oscillator no longer has the full range of frequency tuning. The core of the YIG block is replaced with a spare unit from a different Agilent instrument. After re-alignment of the YIG the unit functions correctly. The principle operation of the YIG oscillator is explained and the internals of the defective unit are examined under the microscope.
In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible failure points are considered. Based on the observation of the noise floor, the most likely cause is the second LO module. The measurement of the LO power indicates that the second LO power is fall below nominal.
The second LO signal (at 3.6GHz) is generated by a DRO PLL module which is locked to 600MHz. The PLL is functional, however the output power is below -20dBm. Teardown of the module reveals a simple design with a doubler and filter. The filter (which is discolored) shows a huge loss likely caused by RF losses due to trace degradation. Thinning the traces provides some improvement and the remaining loss is compensated with a two stage RF amplifier. With this modifications, the instrument’s alignment errors are partially resolved.
The next problem is with the input attenuator at the 20dB range. This problem is simply resolved by providing lubrication on the attenuator solenoids after disassembly. The instrument is then used for various measurements to verify its correct operation.
The Signal Path (TSP) is an electrical engineering video blog for industry professionals, students and hobbyists. TSP is a non-for-profit website dedicated to provide free education spanning a wide range of electrical engineering topics. Equipment reviews, tutorials and repair videos are posted regularly.