The existing decade resistance box shows inconsistent measurements and intermittent contacts prior to the DeoxIT application. After spraying all contacts the instrument is significantly improved with repeatable and accurate resistance measurements. DeoxIT can be purchased from a variety of suppliers and vendors including Amazon.
In this short episode Shahriar takes a detailed look at an Anritsu variable optical attenuator operating in the L- and C-Bands. The mechanical attenuator is defective and provides an opportunity for complete disassembly and examination of the free-space optics, mechanical components and electronics.
The electronics drive a pair of DC motors with potentiometer decoders in feedback along with operational amplifiers and a DAC. This allows the microprocessor to set the exact position of the motors based on calibrated values stored on EPROM. The free-space optics consists of two back-to-back disks with radial metal coatings. Depending on the position of each wheel, the coating limits the transmission of the light through the wheel causing attenuation. The entire housing is hermetically sealed to prevent degradation of the disks.
In this short episode Shahriar takes a close look at an Ist-Rees laser spectrum analyzer. This simple instrument is based on a continuously rotating diffraction mirror to detect various wavelengths. A trigger signal is used to denote the beginning of the scan and the front-panel display shows the current selected wavelength. By aligning the output signal with the trigger signal the wavelength of the input light can be measured.
After the unit teardown, the instrument is used to measure the wavelength of a semiconductor 1310nm laser. The unit is calibrated using this source and is then used to measure the infrared leakage wavelength from a green laser pointer.
In this episode Shahriar performs a full review on the Tektronix MDO4000C series mixed domain oscilloscope, particularly model MDO4104C-6. The MDO4000C combines up to six instruments including a function generator and a built-in spectrum analyzer. Unlike any other instrument, it can synchronize RF, analog and digital channels. These correlated measurements provide insight into difficult to find problems particularly intermittent events.
This review begins with a comparison between the MDO4000B and MDO4000C instruments. The full review of the MDO4000B can be viewed here. All experiments demonstrated in the MDO4000B review are also relevant to the MDO4000C instrument.
The teardown of the instrument reveals a multi-board construction where the ADCs, FPGAs, application processor and memory are on the main system board. A complete analysis of the entire system is presented including the operation of the RF module.
In order to demonstrate the instrument’s capabilities, an encrypted frequency hopping transmitter system is analyzed. The system exhibits various problems such as high BER, low SFDR, poor phase-noise and EVM. The MDO4000C is used to perform advanced measurements across analog, digital and RF domain to track and resolve these problem. The complete block diagram of the experiment can be found here.
In this episode Shahriar investigates a failure of an Agilent 8164A lightwave measurement system. A quick power-on test reveals the main power supply of the unit has failed and has caused catastrophic damage to some of the instrument modules.
After the teardown of the unit the power supply module is examined. Tracing the signal path from the switching transformers shows a pair of damages rectifier diodes. A new component with similar specifications is salvaged from a different power supply. After the installation, the unit can be powered on and detects all the installed modules. Most of the modules are functional, however the main tunable laser module fails alignment. The repair of that component is reserved for another video.
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.