Tag Archive for RF

Signal Hound SM200C/B 100kHz – 20GHz Real-Time Spectrum Analyzer Review, Teardown & Experiments

In this episode Shahriar reviews the long awaited Signal Hound SM200C/B Real-Time 100kHz – 20GHz Real-Time Spectrum Analyzer:

The SM200C is a high-performance spectrum analyzer and monitoring receiver with a 10 Gigabit Ethernet SFP+ port, enabling the SM200C to communicate with a PC over long distances using a fiber optic cable. Designed for remotely-located accurate RF data analysis at the lowest cost possible, the SM200C features:

  • 160 MHz instantaneous bandwidth I/Q streaming over 10GbE
  • SFP+ port for fast, long-distance communication with a PC using an optic cable
  • Device control¬†and¬†data transfer occurs via SFP+ connection, not USB
  • Tunes from 100 kHz to 20 GHz
  • Sweeps at 1 THz/sec at 30 kHz RBW
  • 110 dB of dynamic range
  • Ultra-low phase noise
  • GPIO port antenna switching

The SM200B offers a USB 3.0 PC interface with 40MHz of instantaneous I/Q streaming. Furthermore, the SM200B includes a full 2-second of internal memory at 160MHz of capture bandwidth which an be accessed through the API.

The review is organized as follows:

00:00 – Introduction
00:49 – Overview, build quality and detailed specifications
05:51 – Full teardown, analysis and system architecture
18:00 – 10GbE PC interface using M.2 Key to PCIe converter
19:22 – Experiment #1: FMCW signal analysis, GUI overview & 160MHz capture capabilities
31:33 – Experiment #2: Interfering hunting, FM-versus-time, frequency hopping & advanced triggering
41:32 – Experiment #3: Digital demodulation, phase-noise & equalization
46:02 – Other GUI capabilities, mask & EM compliance, API
47:20 – Concluding remarks

Is 5G Dangerous?

In this episode Shahriar discusses some of the concerns surrounding the 5G Cellular Wireless Technology. It is important to understand the technology and the history of why 5G is unique in some ways compared with 4G LTE.

The evolution of cellular wireless technology is briefly discussed alongside with dangers of electromagnetic radiation across the entire spectrum. 5G mm-wave beam-forming technology is explored and the actual RF power levels at ground level is computed. Finally some questions about science and technology are discussed.

Perhaps this is the quote which captures my feelings toward this whole situation:

I worry that, especially as the Millennium edges nearer, pseudoscience and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive. Where have we heard it before? Whenever our ethnic or national prejudices are aroused, in times of scarcity, during challenges to national self-esteem or nerve, when we agonize about our diminished cosmic place and purpose, or when fanaticism is bubbling up around us – then, habits of thought familiar from ages past reach for the controls. The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.”

– Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark

Teardown & Repair of an Agilent E8257D 250kHz – 31.8GHz PSG Analog Signal Generator

In this episode Shahriar repairs an Agilent E8257D PSG Analog Signal Generator generously loaned by AllTest. Please visit their website for all your measurement, calibration and service needs:

sales@alltest.net
https://alltestchambers.net
https://alltest.net

The instrument does provide an RF output signal. However, there is also a large DC offset voltage present at the output RF port which changes depending the frequency band. The DC voltage is present even when the output RF signal is disabled. Furthermore, the OCXO of the instrument is defective and does not produce a 10MHz output signal.

The block diagram of the PSG is examined in details with emphasis on the final attenuator, coupler and doubler RF decks. Interestingly enough the output offset is traced all the way back to the Modulator Filter block. The teardown of the module reveals a series of PIN diode switches and after some investigation the fault is traced to a damaged PIN diode on the sub-3.2GHz path. Since the diode can’t be easily replaced, the control voltage to the diode is disabled instead which removed the DC offset problem.

The OCXO teardown reveals that during a prior repair, the oscillator module has been damages and torn off the PCB. New pins are added to the oscillator module which returns the crystal back to working condition. The performance of the PSG is verified using a spectrum analyzer and frequency counter.

Teardown & Repair of a Rohde & Schwarz SMBV100A 9kHz – 3.2GHz Vector Signal Generator

In this episode Shahriar takes a look at a R&S SMBV100A Vector Signal Generator which does not produce the correct output level. Despite passing all self-tests and ALC checks, the output power level is far below expectation. The output also shows a high-pass frequency response.

The (heavily simplified) block diagram of the instrument is examined and discussed. The teardown of the unit reveals the output RF board which is presented in details. Since the instrument cannot detect the failure internally, it is very likely that the fault is part of the RPP output RF relay. The circuitry as well as the datasheet of the components are examined. Measurements show that the output RF relay is never activated due to a faulty PMOS transistor. After transistor is replaced, the unit shows the correct output level. The baseband generator functionality is also verified.

You can purchase the Metabo HPT (Hitachi) Cordless Screwdriver Kit from my Amazon Affiliate Link.

Teardown & Repair of an Agilent N9020A MXA 10Hz – 26.5GHz Spectrum Analyzer (March 2020)

In this episode Shahriar takes a look at a malfunctioning Agilent N9020A MXA. This instrument was provided by AllTest who hold the largest inventory of used and refurbished instruments. They have trusted The Signal Path to attempt a repair on the instrument and to support the educational content of this channel. Thank you AllTest! Please visit their website for all your measurement, calibration and service needs:

sales@alltest.net
https://alltestchambers.net
https://alltest.net

The instrument fails RF Alignment despite the fact that all calibration signals are present and can be viewed on the unit. The front-end attenuators also appear to be fully functioning. A full sweep of the input shows that the instrument fails to make measurements between 8.4GH – 14GHz as well as above 17GHz. The block diagram is analyzed and the likely fault is traced to a doubler circuit on the A13 RF Assembly. The teardown of the assembly along with step-by-step reverse engineering is presented. An X-Ray of the module also reveals the hidden band-pass filter structure on the PCB. Various dies are also examined under the microscope. The A13 module is replaced with which corrects all the instrument faults and returns the unit to normal operation.

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