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.
In this episode Shahriar investigates a peculiar problem with an Agilent P-Series Power Meter. While the instruments works during startup, after about 10 minutes the LCD screen begins to flicker and become scrambled. Initial investigation reveals that the issue is not likely with the main motherboard since USB connection to the instrument and data-readout is possible even when the LCD screen is malfunctioning.
Teardown of the unit reveals a modular design where a ribbon cable connects the front panel to the motherboard. Moving the cable around affect the LCD which points to a faulty cable connection. The failure is at the only ribbon cable without a proper removable connector to the motherboard. The cable is cut, re-crimped and the solder joints re-worked. This appears to solve the LCD problem. The performance of the unit is verified by measuring the output power of the Tektronix TSG Vector Signal Generator.
In this episode Shahriar explores the cause of failure of an Agilent E4405B ESA 13.5GHz spectrum analyzer. In a previous episode, an E4407B version of the ESA was repaired and upgraded which is helpful in debugging and analyzing this instrument. The instrument displays LO Unlock which is a familiar problem. After an overview of the system block diagram, the LO signal path is traced and analyzed for problems.
After some investigation, the problem appears to be identical to the E4407B model repaired before! The Hittite (Analog Devices) divide-by-4 static divider unit has failed and does not divide correctly at high frequencies. The component is replaced which restores the instrument’s functionality.
The LCD screen of the unit is also very dim. The CCFL tube and the inverter are replaced with an LED back light instead. The unit then produces a bright and vibrant graphs and text. The performance of the instrument is verified with a Keysight MXG signal generator.
In this episode Shahriar presents a full teardown, analysis and review of the Siglent SSA3000X Series Spectrum Analyzer. Siglent’s SSA3000X family of spectrum analyzers offer a frequency range of 9 KHz to 2.1 GHz / 3.2 GHz. With their light weight, small size, and friendly user interface, the SSA3000s present a bright easy to read display, powerful and reliable automatic measurements, and plenty of impressive features. Applications are many, but include research and development, education, production, maintenance, and many more.
The review is organized as follows:
00:41 – Model comparison and overview.
03:56 – Full teardown and analysis of internal hardware.
17:38 – Initial performance assessment including tracking generator behavior.
29:50 – Antenna and diplexer measurements and characterization.
50:00 – Built-in applications overview and measurement personalities.
56:58 – PC interface software performance and overview.
In this episode Shahriar investigates a faulty Agilent 53152A 46GHz frequency counter. The instrument does not power on and shows no sign of internal voltage presence. Teardown of the instrument reveals a large PCB where all analog and digital circuity is contained. The power supply module is a module components and upon measurements shows no activity.
The power supply is a simple switching architecture with functioning input rectifier and capacitor filter. By using an oscilloscope it is clear that the power supply PWM controller attempts to start. However, the main power supply pin shows unstable voltages indicating inadequate charge retention on the rectifying capacitor. Replacing the capacitor revives the startup condition and the power supply function returns. The PWM controller and main switching transistors are also replaced with new ones. After this repair the unit powers on and passes all self-tests. The unit can successfully measure signal frequencies and power.
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.