In this episode Shahriar takes a close look at a faulty Agilent E4433B 4.0GHz signal generator and vector modulator. This instrument is equipped with many of the most useful options such as dual arbitrary waveform generator and high-power output.
The instrument does not generate any error messages, however the output signal is ~20dB below specifications. After presenting the system block diagram and observing the output power characteristics, it becomes clear that the issue is with the mechanical attenuator. The teardown of the attenuator reveals faulty o-rings on the 5dB attenuation pad which has to be repaired with some flexible epoxy.
After the repair the instrument’s functionality is verified by measuring the output power with a power meter, frequency accuracy with a Rubidium frequency counter and the modulation accuracy with a vector signal analyzer.
In this episode Shahriar repairs a non-functional N4901B 13.5Gb/s BERT mainframe. This instrument is equipped with both the generator and analyzer modules which makes it fairly valuable. The instrument does not power on and does not react to the soft power button.
Teardown of the unit reveals a TD-Lambda Vega power supplies series which is a fully configurable switching power supply design. Even though the power supply in the instrument is completely custom, it is made from generic sub-blocks readily available on eBay. A replacement front-end is purchased to repair the power supply after detecting the problem.
The instrument also shows a minor problem with falsely detecting an overload condition on the delay control port which is by passed by installing an overwrite switch. The instrument performance is verified by generating and measuring various eye diagrams through a back-plane PCB board.
In this episode Shahriar continues his review of the Tektronix 5-Series 8-Channel MSO Oscilloscope following the original overview of the instrument. A full teardown of the instrument as well as a set of experiments showcasing the new Spectrum View capability are shown. This review is organized as follows:
00:09 – Introduction and outline
01:31 – Teardown and analysis of the acquisition board
13:38 – Experiment setup and description
16:59 – Measurement results and Spectrum View capabilities
33:12 – Concluding remarks
In this episode Shahriar reviews the very unique SAF Spectrum Compact V-Band portable spectrum analyzer. These battery powered devices do not require external down-converters, and a particularly useful tool for any field engineer performing microwave equipment installation, link troubleshooting, site planning and maintenance. The analyzers utilize a resistive touch screen, allowing the engineer to wear gloves when using the device. The Spectrum Compact can be used for high precision detection of existing interference on installed paths or available radio channels. Data logging of all spectrum scans is available with the Spectrum Compact device, and enhanced data processing and analysis are provided by SAF Tehnika designed PC software for your laptop.
The instrument teardown reveals a multi-board design and each module’s functionality and design is presented. The unit is then used in several experiments to track and analyze various V-Band RF signals. The review is organized as follows:
01:00 – Overview and model comparison
03:16 – Instrument design, overview power-on benefits
05:23 – Instrument GUI overview
09:56 – Full teardown and analysis of all modules
19:22 – Experiments with various unknown V-Band RF signals
29:43 – PC software overview and capabilities
31:30 – Concluding remarks
In this episode Shahriar repairs an Agilent N9020A MAX Spectrum Analyzer. The instrument is well equipped with real-time capability and direct I/Q input ports on the front panel. The instrument does not show the correct signal levels and fails internal calibration.
After a brief teardown, the block diagram of the instrument is carefully examined for potential failure points. It is determined that front-end switch and mechanical attenuator is likely faulty. Teardown of the unit reveals significant damage to the attenuator due to some high-power at the input. Unfortunately, this also implies that the front-end RF selector and pre-amplifier modules are also damaged. In the second repair video, the front-end module is disassembled and damage to the dies can be observed.
Luckily, a relatively inexpensive front-end (SSLAM) unit is sourced from eBay and the repair is completed. The performance of the unit is verified after the repair and the front-end I/Q input functionality is demonstrated.
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.