Phase Noise Measurements of Homemade and Commercial Oscillators and Signal Sources

Having an FSUP Phase Noise Analyzer on loan for an oscillator project (thanks N1UL !) I had the chance to check the phase noise of some commercial and homebrew oscillators and signal sources.

Example:

PhaseNoise10MHzRubidiumStandardLPRO1Hz1MHzFSUPThis a an EFRATOM LPRO101 Rubidium Standard. I also measured a commercial MillRen OCXO, a GPS standard, a Keysight N5171B RF signal generator and a RIGOL DG1062Z.

Click here to see some Phase Noise Measurements of Commercial and Homemade Oscillators …

Silly Circuits -Unusual Behaviour of Crystal Oscillators

Normally, crystal oscillators are standard components, used thousands of times without too much engineering attention necessary. If it comes to high quality crystals, a lot of unexpected effects can occur, like generating several nonharmonic frequencies at the same time and even chaotic behaviour.

here in the time domain:

Click here to see some Unusual Behaviour of Crystal Oscillators …

Using the Keysight AutoProbe Interface in Your Own Projects

As an owner of some Keysight equipment I wanted to use some probes intended for the Oscilloscope AutoProbe connector on other test equipment like VNAs or spectrum analyzers. I asked how to do this at the Keysight forums, but nobody had an answer for me there except that it does not work.

OK, lets homebrew something and see how far we get.

AutoProbeAdapterStraightMountCasePictureFrontAutoProbePsuAndDriverOutsidePicture

KeysightAutoProbeInterfaceSnifferWithCurrentProbeFetProbeSmdV13RWithCasePicture

To make a long story short, it worked after a while of research and testing.

Click here to See Using the Keysight AutoProbe Interface in Your Own Projects …

Measuring Power Supply Output Impedance Using a VNA

MeasuringPowerSupplyImpedanceWithShuntThruMethodStep4UtilityCircuitsForVnaPowerSupplyMeasurementsPicture

Output impedance is a key quality criteria for a power supply. If a PSU is any good, it is very small. Now, how can something like this be realiably measured over a rather large frequency span ? People from Keysight and other companies have derived a bag of tricks how this could be done with “standard” (*) VNA equipment. I got my hands on two of those, the Keysight E5061B-3L5 VNA that goes from 5Hz to 3GHz, and the Bode100 from Omicron Systems that works from 1Hz to 50MHz.

It can be done – with a bag of tricks. Here are the gory details …

Click Here for Making Power Supply Measurements with a Vector Network Analyzer …


(*) Standard means that you can buy this off the shelf, but it does not mean its cheap or simple in any way. The Bode100 is about 4.5k€, and an E501B-3L5 is about 35k€ (list prices).