8874's have a 4 digit date code on the anode cooler.
----- Original Message -----
From: "Eric Rosenberg" <email@example.com>
Sent: Friday, February 25, 2011 9:58 PM
Subject: [Amps] Determining the Age of A Tube?
> I'm using a borrowed ETO 78 (early vintage). The person loaning it to me
> (K2PS) has no idea how old the tunes are... he hasn't changed them. Last
> weekend (ARRL DX CW) we didn't get more than 1kw out, with lots less than
> that on 15 and 10m.
> We know the tunes are soft, but how soft are they an dhow do we find out?
> Thanks & 73,
> Eric W3DQ
> Washington, DC
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