U229A U231A

By Gary Boyd; posted April 12, 2020

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Trying to figure out if these are U229A (left) U231A (Right). Checking the 2nd ed. book the 231A does not list any insulators. This one has an unglazed pin hole. The book only lists the 229A no name "G" but the one I have showing is not a "G" color and looks like it has a MLOD with a glazed pin hole.