[davemc]

I have a Philco 66 on the bench. While testing the tubes, I noticed that ALL were branded PHILCO and had similar appearance and date codes. I had no luck on finding information on the web for early Philco tubes. This radio had had some servicing (volume control, line bypass cap) but was otherwise all original.

I was wondering if the tubes were the originals as shipped? All the codes are arranged vertically, with a LETTER and a NUMBER. The codes I found were (first figure on TOP) 78: 5C, 6A7: H5, 75: C5, 42: B4, 80: B4. Looks like a month (letter) and year (number) - but just guessing.

Does anyone have a reference on-line? I do NOT have Lud's book.

Thanks,
Dave

[Alan Douglas]

The number is the last digit of the year. Letters are months: C is January, B is October and H is February. After September 1935 the month codes changed: B is February, C is March, H is August.

In either case it seems odd to have dates so far apart (I'm quite sure Philco did not stockpile tubes for months).

These are Sylvania codes, and it's possible Philco bought tubes from someone else, which would have different codes.

[davemc]

Is this information in the book Tube Lore or another source? It is just curious that at least the YEAR is close to the introduction date of the radio. I would not suspect that the tubes would have been changed so soon. And they are all branded Philco.

Thanks!