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Message ID: 2655     Entry time: Fri Feb 19 00:52:40 2021
Author: rana 
Type: Electronics 
Category: Electronics 
Subject: inspecting W diode driver 

I have the old "W" driver which was labeled as noisy in the EE shop. This is the one that Aaron saw a ~10 MHz oscillation on. E-traveler # S1500270.

With the Moku, I didn't see any oscillation. There was some noise at a few of the monitor points, but not sure yet if that was the Moku noise or the circuit.

There has been some modification of this "V3" circuit. Although the knobs make the correct voltage change in the early stages of the circuit, the resulting voltage does not make it through the summing and filtering stages. Need to look up Johannes's elog and see what was done to this and why.

  • Zach elog where he changes the knob range and measures the resulting Amperes/Revolution
  •  

 

also, here's a link to Johannes's measurement of current drive noise with a transformer. Apparently he used a resistor (no diode), and our sub-nV transformer. SR560 by itself might be fine too.

On the Moku, and also on RF spectrum analyzers, "dBm" stands for "dB mW", not "dB mV". Its a measure of RF power into a 50 Ohm load. i.e. mW = 1000* (Vrms^2)/50. And 0 dBm  ~ 222 mV rms, -40 dBm ~ 2 mVrms.

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