Archive for Teardown

Signal Hound PNCS-1 1GHz Phase Noise Clock Standard Review, Teardown & Experiments

In this episode Shahriar takes a close look at the new Signal Hound PNCS-1 clock standard module. The purpose of this instrument is to provide an exceptionally clean phase noise reference at 1GHz in order to characterize other instruments such as spectrum analyzers and oscilloscopes.

The unit uses an OCXO at its heart running at 100MHz. The signal is them multiplied by a factor two and then a factor of five while being filtered and amplified in order to generate 1GHz. The complete signal path of the instrument is analyzed. The unit is then used on an Agilent MXA generator to characterize its phase noise. A frequency divider is also used in conjunction with the PNCS-1 in order to create lower frequency signals.

Teardown, Repair and Experiments with an Agilent E4981A High-Speed Capacitance Meter

In this episode Shahriar investigates an Agilent E4981A high-speed capacitance meter which fails self-test during startup. The instrument reports a series of errors associated with the CPU board. The teardown reveals a multi-board construction where the main analog assembly employs an FPGA for control and interface to the main CPU board. The unit has a disconnected ribbon cable between the analog board and the main CPU assembly. After correcting the problem the instrument completes self-test without errors.

After the repair the unit is used to measure several known capacitors for functionality verification. Finally the instrument is used to measure a hand-made parallel plate capacitor. The capacitor can accept various types of dielectric material whose impact is studied.

Teardown & Repair of an Agilent E4440A 3Hz – 26.5GHz PSA Spectrum Analyzer

In this episode Shahriar takes a close look at a defective Agilent E4440A spectrum analyzer. Initial analysis reveals that the startup errors are caused by a defective pre-amplifier module. During initial alignment and calibration, the defective microwave relays inside the pre-amplifier module fail insertion loss specifications and cause alignment failures.

Unfortunately, the relays are not repairable and must be replaced. Two new relays are purchased and replacement clears all alignment issues. The main motherboard battery has also failed; a replacement battery corrects any time and date keeping errors. The repaired instrument is cycled through several alignment procedures without any problems. The performance of the unit is verified by examining the DANL of the instrument with and without the pre-amplifier activated.

Siglent SDG6000X Series Arbitrary Waveform Generator Review, Teardown & Experiments

In this episode Shahriar takes a close look at the newly released Siglent SDG6000X Series Pulse / Arbitrary Waveform Generator. SDG6000X is a series of dual-channel Pulse/ Arbitrary Waveform Generators that feature up to 500MHz output frequency, a maximum sample rate of 2.4GSa/s and 16-bit vertical resolution when used as a function generator. The particular reviewed model is the SDG6052X which is the top-end model.

The full teardown of the unit reveals the internal architecture of the instrument, DAC / FPGA interconnect as well as the output amplifier structure. Although the limitations of the FPGA prevents the instrument to operate at full 2.5GSa/s in arb-mode, the instrument is capable of providing complex modulation up to the full 500MHz signal bandwidth.

This comprehensive review is organized as follows:

00:01:11 – Siglent SDG model overview and comparison
00:03:10 – Front and back panel overview
00:06:24 – Full teardown and analysis of the instrument archietecture
00:18:19 – GUI overview, menu structures and built-in functions
00:22:31 – Waveform phase and amplitude accuracy, characterizing a 180-degree hybrid
00:30:42 – Large-signal generation, ultra-sound experiment and range measurements
00:36:38 – Pulse generation performance, spectral content and low-pass filter measurements
00:44:07 – THD measurements, harmonic generation, Two-tone TOI measurements using waveform combine function
00:50:30 – PRBS pattern generator, ISI measurements and eye-diagram impairments using waveform combine functions
01:01:57 – I/Q modulation and waveform creation using EasyIQ as well as superheterodyne up-converter measurements
01:10:44 – Concluding remarks

Teardown, Repair & Upgrade of an Agilent 3458A 8.5 Digit Digital Multimeter

In this episode Shahriar repairs and upgrades an Agilent 3458A 8.5 Digit Multimeter. The instrument has been kindly donated by AllTest Instruments Inc. You can access their website here, as well as their eBay store, Bonanza store and TestUnlimited hub. AllTest provides the following:

  • Massive inventory of test and measurement equipment with over 20,000 units to chose from.
  • Full service general laboratory where repairs, refurbishment, and testing are carried out.
  • An additional NIST traceable metrology laboratory with extensive T&M capabilities where OEM grade calibrations are performed.
  • 5% discount on any purchase when The Signal Path Blog is mentioned for first time customers with limit one per customer.

The 3458A unit fails startup conditions with several errors. After close inspection of the boards, the initial problem points to a poorly plugged in fiber-optic cable. After this fix, the unit still fails ACAL on the AC Board. The unit’s NVRAM modules all have to be replaced. During this process the memory of the unit is also upgraded and the firmware is updated to the latest available version. After analysis of the schematics the problem is traced to a damaged JFET input operational amplifier on the attenuator flatness calibrator unit. The replacement allows the unit to pass all self-test and ACAL calibration. The instrument is then NIST calibrated by AllTest Instruments and shows excellent performance when compared with various multimeters in the lab.

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