The aim was, guess what? Suppressor-grid modulation! I can remember
hearing some of these rigs on the air. I don't know just what percentage of
modulation was possible, but I remember it being pretty weak. Good strong
signal with very low modulation level.
The aim had been to use what parts one had, and it surely was an
inexpensive
way to join the AM crowd!

Old Chief Lynn, W7LTQ

In the 1957 ARRL Handbook, these particular tubes were also used in a cathode
driven (grounded grid) amplifier.

73, Barry WA4VZQ

Yes, I was aware of the "modified 1625" but for linear amplifier usage. Now I
know that they were also used for suppressor-grid modulated stages.

But now a doubt come to my mind: the 1625 is a beam-power tube, not a pentode
(actually it is an 807 with 12.6V filament). So, how could it work in
suppressor-grid modulated stages?

73

Tony I0JX