[AMRadio] Mfg date for 4-400 series

Rick Brashear rickbras at airmail.net
Sat Mar 24 09:32:36 EST 2007

Hi Barrie...

In your HB-3, where exactly is the 4-400 data located?  I found mine in the
Transmitting volume and the other 4-tubes in last volume of the original
set.  I was also surprised to find only one (1) sheet of data.  Is this
consistent with your HB-3?


I have an HB-3 here that shows a data sheet for the 4-400A dated 9-62.

I also have an Eimac catalog from the early 1950s that shows the 4-400.

73, Barrie, W7ALW

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