LM317LZ Regulator Circuit on ProgRock
While building & testing my ProgRock with Si5351A Synthesizer kit & testing the supply voltages, I find that the 5 volt rail is at 5.25V & the 3.3v rail is at 3.8 volts. This is using the recommended procedure of putting the LM317LZ on the ProgRock board & using the noise filter section to feed the Si5351A board.
In an effort to compensate, I replaced R2 (3k nominal) with a 2.7k value; no help, still had higher than desired voltages.
Next I replaced the LM317LZ, keeping R2 at 2.7K; same high voltage readings.
Is this ordinary?
These measurements are made without IC1 installed on the ProgRock board nor the Si5351A board plugged into the ProgRock board; i.e., no load conditions.
Robin Midgett K4IDC
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