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Table of Contents
Raspberry Pi XO Replacement
Success!
Made an initial attempt on the evening of 2023-03-26 on a Pi 2 B. Drop in replacement is working surprisingly well right off. Have not performed any longitudinal testing yet, but initial tracking numbers are positive.
Notable Test Points
PP3 GND PP4 GND PP5 GND PP6 GND PP7 5V after polyfuse PP8 3V3 PP9 1V8
Pi 3 B v1.2 Stock XO
Marked AEL19.2
New TCXO
Test Cases
Before I do this swap, I need to get a benchmark of (at least) two identical Pis so I have a baseline of their performance in stock configuration. These systems need to be as identical as possible, both in terms of software load out as well as their physical deployment.
Software
- OS - Alpine Linux 3.17
- Timekeeping/measurement - chrony
Configured to be as light and slim as possible.
Physical
This will be an isolated test, no
Power
Meanwell 5v PSU powering both Pis - “back feeding” through the 5v pin on the 40p header. AC PSU connected to a UPS to protect against brownouts or extended outages.
Environmental
Both Pis enclosed in a single styrofoam enclosure, as close to each other as reasonable. Placed in a location that is as temperature stable as possible (no direct sunlight, no temp swings from HVAC adjacency, etc.)