"A final note on this issue: 1625's are 807's with 12.6V filament, all other
parameters are the same.
73's
Sam HS0ZDY"
Almost - but not quite
Some of the 1625 tubes were manufactured with a wire connecting the
suppressor grid to the cathode - external to the envelope, but inside the
socket. The enterprising amateurs discovered this and found how to
disconnect this wire from the cathode for true grounded grid. The 807's did
not have this feature. A judicious hacksaw to the base at just the right
point allowed extraction of the suppressor wire. No more diffucult to do
than a root canal. With glee, the amateur would get on the air saying he
was using modified 1625 tubes.
So, some 1625 tubes could be used in grounded grid (such was the case with
the P & H linear), whereas none of the 807's could be used in such a
configuration.
If 6 volt tubes were desired, the 837 could be used, as it had a separate
suppressor. However, it also had less dissipation.
73, Colin K7FM
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