Reverse Engineering a Wavetek OCXO Board

I bought a Wavetek OCXO board a long while ago. My original plan was to remove the onboard crystal oven to replace the broken OCXO in my HP 5350B. But since I later managed to fix the original OCXO , this board had been sitting quietly in one of my component bins collecting dust.
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Building A Tracking Generator

In this blog post, I will show you how to build a 0 to 5.8 GHz tracking generator for the HP 8566B 100 Hz to 22 GHz spectrum analyzer using off-the-shelf components for under $100. Although this tracking generator is specifically designed for my HP 8566B spectrum analyzer, the method discussed below is applicable to pretty much any spectrum analyzer that has an LO output (typically the 1st LO).
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Tracing Filter/Oscillator Frequency Response Using Spectrum Analyzer and Signal Generator

In this blog post, Let’s take a look at how to measure a filter’s frequency response using a spectrum analyzer and a signal generator. Typically, a tracking generator is preferred for this kind of scalar network analysis as its center frequency is in-sync with the frequency the spectrum analyzer’s bandwidth filter is currently tuned to. But with a good signal generator, we can manually sweep across the desired frequency range and obtain similar amplitude versus frequency measurements.
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AM/FM Demodulation Using HP 8566B Spectrum Analyzer

In my previous blog post, I did a quick teardown of my HP 8566B spectrum analyzer. In this post, I will discuss how to use a spectrum analyzer like this to demodulate an AM or a FM signal. A video including the theory and a few experiments is linked towards the end.
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Some Pictures of My HP 8566B Spectrum Analyzer

The latest addition to my lab is an HP 8566B spectrum analyzer. This isn’t just any spectrum analyzer, it was perhaps the best spectrum analyzer money could buy back in the late 80’s. While it was discontinued in 1997 and has long become obsolete, its performance remains quite impressive even by today’s standards and still rivals that of many of its modern counterparts.
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ESR Measurement Using Multimeter and Function Generator

Capacitor ESR (Equivalent Series Resistance) measurement is very useful in diagnosing issues with power supplies. In linear power supplies, a high ESR filter capacitor may cause excessive ripple current on the voltage rails and can cause the capacitor to overheat due to its increased resistance. In low dropout linear supplies, the ESR of the output capacitors affect the loop stability and excessive ESR in these output capacitors can make the power supply unstable, which in turn can lead to out-of-tolerance voltage being applied to the load and could cause future damages. In switching mode power supplies, the ESR of capacitors are even more critical. In this blog post I will discuss how to measure the ESR of a capacitor using a function generator and a multimeter. A short video on this topic is also included towards the end.
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Exploring the Battery Option of the EDC/Krohn-Hite MV216A DC Voltage Standard

In my previous blog post, I did a teardown of the EDC/Krohn-Hite MV216A DC voltage standard and measured the temperature coefficient of its reference Zener diode. And as I promised, this time I will explore its internal and external battery options.
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EDC/Krohn-Hite MV216A DC Voltage Standard Teardown and Tempco Measurement

In this blog post, we are going to take a look at Electronic Development Corporation’s (EDC, acquired by Krohn-Hite in 1998) MV216A battery/external powered DC voltage standard and also measure its voltage reference’s temperature coefficient (tempco). A teardown video is also included towards the end. MV216A is a six decade precision DC voltage standard, it can output from 0.1µV in 100mV range all the way up to 11.1111V in 10V range. Voltage standards of this caliber are usually used as calibrators to calibrate multimeters and other test instruments.
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The Spectrums of Three Cheap Laser Pointers

A couple of months ago, I converted my EP200Mmd monochromator into a scanning monochromator and tested the spectrums of quite a few light sources. This time, I will take take a look at the spectrums of three cheap eBay laser pointers using the same technique.
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Interfacing HDC1050 with Arduino

Recently, I got my hands on TI‘s HDC1050 low power, high accuracy digital humidity/temperature sensor chip. The supply voltage of this chip can range between 2.7V and 5V, making it possible to interface with 5V MCUs such as Arduino directly. I created an Ardunio library for this sensor and will discuss its usage in this post. The code can be downloaded towards the end and can also be found on my GitHub page.
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Direct Measurement of the Speed of Light using a Cheap Laser Diode – II

In my previous blog post, I discussed the basic TOF method for direct measurement of the speed of the light. In order to measure the time of flight accurately, we need to be able to both generate and detect very fast rising signals. One way to generate a fast rising, short duration laser beam is via an avalanche pulse generator as we discussed previously. In this blog post, we will take a look at the receiver end and conduct some experiments. A video of the experiment is included towards the end.
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Direct Measurement of the Speed of Light using a Cheap Laser Diode – I

Speed of light c in air can be measured either directly or indirectly. There are many ways to infer c with indirect measurements. For instance, we can measure the propagation delay of a signal through a coaxial cable (or an optical fiber) using the TDR analysis. With the length of the coax or optical fiber known, the speed of light can be calculated using the known velocity factor (or the refractive index of the fiber) and the measured propagation delay. Another example of indirect measurement is to measure the wavelength of a known frequency standing wave (e.g. a microwave signal) and derive the phase velocity of the electromagnetic wave in air.
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Testing Unknown Transformers with Function Generator

Last week, I posted a YouTube video explaining how to use a function generator to test an unknown transformer. I have received quite a few questions since so I thought I would explain this topic a bit more in detail here.
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Keithley 706 Scanner Teardown

I bought this Keithley 706 scanner on eBay a while ago. This scanner can take up to ten different scanner cards and is typically used in an automated testing environment. In this blog post, I will show some of the teardown pictures and a couple of the scanner cards (7064, 7152) included in this unit. A quick teardown video is included towards the end.
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Yet Another Scanning Monochromator Build

A while ago, I saw a video on the signal path in which Shahriar modified his Verity EP200Mmd monochromator/detector and turned it into a scanning monochromator. Inspired by his work, I decided to do something similar. Since I do not have the equipment to make the mechanical pieces, I decided to take another route. In this post, I will show you a simple and non-intrusive way to make the EP200Mmd a scanning monochromator. A video discussing the build and some experiments is included towards the end.
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