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.
In this episode Shahriar presents a meticulously prepared set of educational lab kits on Power Conversion by Texas Instruments. These kits include Buck, Boost, LDO and Buck-Boost power conversion courses complete with a beautiful set of lab instructions and PCBs. Each kit describes up to 7 different exercises which demonstrates various aspects of power conversion characterization and design challenge.
In particular the Buck Lab kit is examined. The PCB is populated with two different Buck DC-DC converters which are carefully described in the lab kit. The first experiment of the lab kit is performed which involves measuring system efficiency under various load conditions and switching frequency. The inductor current, MOSFET switching voltage and output waveform are examined on the oscilloscope.
In this episode Shahriar demonstrates the principle of operation of a purely passive Weston watt-meter manufactured in the 1950’s in Newark, NJ, USA. This watt-meter makes no use of active devices (tube or solid-state) and yet is able to measure real-power both at DC and AC.
The teardown of the unit shows the construction of two coils interacting to advance the needle on the display. One coil produces a magnetic flux proportional to the current input and the other coil produces a magnetic flux propositional to the voltage. The interaction of the flux moves the needle proportional to the total power which is the product of current and voltage. The instrument is then used in conjunction with a power supply and electronic DC load to verify its functionality.
In this episode Shahriar investigates the failure of a GW Instek 1080W power supply capable of providing up to 80V and 40A of programmable output voltage and current respectively. The power supply does not power on. However, relay noises can be heard inside the instrument during power on.
Teardown of the unit reveals a modular design with PCBs on all sides. The instrument comprises 6 different modules and 3 complete power supplies in parallel. The controller circuit is powered from the middle power supply module. Examination of the boards reveals three separate failed devices. The in-rush power resistor which prevents the main supply board from startup, a damaged MOS power transistor on the supply output and surface mount resistors. All components are replaced. The instrument’s performance is verified with a BK Precision 8601 electronic load.
In this episode Shahriar reviews three mailbag items. There is also a new giveaway! Follow the instruction at the beginning of the video to enter. The reviews are organized at follows:
00:09 – Introduction & Giveaway Details
02:21 – Leo Bodnar Electronic – Fast Pulse Generator
These fast pulse generators are rated to below 25ps! The modules are examined and various microwave and design considerations are explored. The block diagram and functionality of the final output driver is also described in details. The units are used to measure the rise and fall time of various oscilloscopes ranging from 300MHz to 13GHz of analog bandwidth. You can purchase your own fast pulse generator here.
21:11 – SV1AFN GPS Disciplined Oscillator
This GPS disciplined oscillator not only provides frequency synchronization to the GPS clock, it also provides programmable outputs on two independent channels using a Silicon Labs synthesizer IC. The complete module acts as standalone unit which only requires power and GPS antenna connection. The full schematic and block diagram of the synthesizer chipset is presented along with measured output waveform, frequency an phase noise at 1GHz. You can purchase your own GPS DO here.
33:28 – Sain Smart USB-C TS80 Portable Soldering Iron
This soldering iron which supports QC 3.0 is the followup of the very popular TS100 soldering iron. The unit can operate with up to 18W of power from 9V. However, it does not support PD on USB-C. By using the AVHzY USB tester the power bank can be configured to provide any desired output voltage and deliver up to 28W into the TS80 soldering iron. Using this method, the TS80 soldering iron can easily solder large components on a wide ground plane. The TS80 soldering iron can be purchased here or internationally from here. The Ankar PD+ 28600mAh power bank can be purchased from here and the AVHzY USB tester can be purchased here.
A laptop for Macy who is about to start college
New shoes for Emily who loves to walk around campus
New Clothes for Myla who loves to play outside
A new pair of school shoes for Lemon who loves all sports
A new digital watch to remind Kevin to take his medicine
A new coat for Thad to stay warm and look cool
New clothes for Sharain who is looking for new employment after graduation
New work clothes for Christine who is excited to start her new job
A new Desk Lamp for Cristal so she can focus on homework
Sensory tools for Wyatt who needs a bit of extra help
Safe transportation for Shakeny who loves musica
New clothes for Isaiah who is very clever
Some new clothes for Katelyn who is making a change in her life
A new pair of sneakers for Sohelia the avid dog walker
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.