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Message ID: 4     Entry time: Tue Mar 16 15:04:10 2021
Author: aaron 
Type: HowTo 
Category: Active Components 
Subject: learned how to phase lock marconi to RF signal 

Chub dropped off a repaired Marconi 2023A signal generator, which I'm phase locking to a function generator to test out how it will go in my three corner hat measurement. Perhaps I could synchronize between the Moku phasemeter frequency estimate (of f_13, f_23) and Marconi frequency estimate (f_12) offline by introducing a time offset to f_12 and maximizing the correlation with f_13 and f_23?

Here's what I did. See attachment 1 for configuration. 

  1. Set the function generator for 27.1828 MHz sine at 0 dBm, to simulate my beat note signal
  2. Select an appropriate mixer and low pass filter. I have a BNC connected LP at 11 MHz that will work, and use a mixer that's for 0.1-500 MHz.
  3. Set the Marconi carrier to a few kHz away from the function generator (27.18 MHz) and 10 dBm RF power (so 7 dBm gets to my mixer after monitoring half the power)
  4. Use externally driven frequency modulation with DC coupling. With no amplifier in the loop, I found the loop is stable up to the maximum 200 kHz/Vrms frequency deviation (modulation depth). With an SR560 and G=100, the PLL locked at 5 kHz/Vrms and was stable up to 11-12 kHz/Vrms.
  5. The LF output on the Marconi is the frequency noise of the RF signal (for example, from the function generator) in units of the FM deviation. 
Attachment 1: IMG_0332.jpg  375 kB  Uploaded Tue Mar 16 16:07:34 2021  | Hide | Hide all
IMG_0332.jpg
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