In this episode Shahriar repairs a malfunctioning Agilent N5182A MXG Vector Signal Generator. While the instrument operates perfectly above 250MHz, below 250MHz the output is very low with a significant increase in the noise floor.
The block diagram of the synthesizer is presented showing various RF signal paths. It is shown that the sub-250MHz band is derived from a hetrodyne section which is where the problem located. Using a EM probe, various signal flows are discovered on the main board and compared with the block diagram. The main problem is traced to a doubler circuit which generates a 1-GHz LO signal for the hetrodyne section. The doubler comprises a transformer coupled to a dual diode surface mount IC. The IC is replaces which restores the doubler functionality and repairs the instrument.
In this episode Shahriar examines a failed Agilent 1169A 12GHz Smart Active Probe. The probe does not get recognized by the oscilloscope and therefore cannot be calibrated. The instrument uses an I2C interface to the probe to download the probe’s specifications and characteristics.
The probe teardown reveals a simple I2C EEPROM IC. After removing the IC it becomes clear that the chip is damaged and must be replaced. A duplicate probe is used to copy the EEPROM data onto a new IC which revives the probe. With the help of the community, the CRC checksum code is discovered and the probe is assigned a new serial number.
In this episode Shahriar reviews the new Tektronix AFG31000 Arbitrary Function Generator. The AFG31000 series with InstaView™ technology is the first high-performance AFG with built-in waveform generation applications, patented real-time wave monitoring, and a modern user interface. The instrument is capable of 2GS/s waveform generation up to 250MHz and 14-bits of vertical resolution. This review is organized as follows:
00:08 – Introductions
01:01 – Front panel, rear panel and instrument design
03:44 – Detailed teardown, analysis, architecture and components
17:30 – GUI overview and basic functions
20:25 – Broadband FM modulation experiments
23:55 – InstaView experiments with a non-linear impedance
35:38 – Equation editor, waveform builder and advance sequencing
51:21 – Concluding remarks
In this episode Shahriar takes a look at a non-functional R&S FSEK 40GHz spectrum analyzer. The instrument’s LCD screen back light no longer works and the front glass is broken. Furthermore, no testing can be done until these problems are resolved. The CCFL tube is replaced with an LED counterpart and a new front panel glass is also installed.
After power on it becomes clear that the instrument has other defects. The internal PLL is unlocked. It is observed that the OCXO module is cold and potentially not working. Examination of the LO board shows a bad inductor on the DC filter side. After this problem the instrument operates correctly but only for signals below 7GHz. After further testing it is discovered that the YIG tuned filter on the pre-selector path is not tuning at all. Eventually the fault is traced to some operational amplifiers on the YIG driver board. The repaired instrument is verified for correct operation.
In this episode Shahriar reviews the Keithley DAQ6510 6.5-Digit Data Acquisition & Multimeter. The instrument offers a new level of simplicity. The DAQ6510 has a touchscreen user interface that enables faster setup time, real time monitoring of test status, and detailed data analysis on the instrument. This review is organized as follows:
00:08 – Introductions
01:57 – Instrument specification and datasheet
03:06 – Unit overview & design
05:41 – DAQ6510 teardown and analysis
11:39 – Keithley 7700 acquisition module teardown
16:38 – Power on and GUI overview
18:29 – Component binning experiment with advanced triggering
28:31 – Analyzing DC-DC converter behavior at 1MS/s
32:06 – Thermal monitoring and modeling using DAQ6510
42:35 – KickStart PC software capabilities
45:43 – DAQ6510 buit-in App ecosystem
48:00 – Concluding remarks
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.