"Dan wrote that the regeneration in his receiver is controlled by a
pot
which varies the plate regen voltage. I saw this method was popular
mainly in old books (ARRL from 30's and 40's for example) but later the
most popular became a control on the screen grid. Does it mean, that
the second method is better ? Why ?
Sorry if my question is naive but I'm beginner, especially in tube
stuff. "

Actually my regen tube is a high mu triode (1H5GT), so there is no
screen voltage to control. A lot of folks like to use throttle caps to
control regen, but pots are easier to mount and don't take up quite as
much space. (I know that a lot of people will disagree with me here on
my choice).

My second audio tube is a pentode (1C5GT) and I use a one meg pot on
the grid to control the volume for the set. I also have a 10 ohm pot
on the first audio tube (1H5GT) filament which also helps control the
volume and nulls out hum.

In case you are wondering why I chose these tubes, they are the tubes
that were used in the old battery sets and have low battery drain
(although I use a battery eliminator anyway for my power source). They
are also very cheap and plentiful.

I also was able to "steal" the engineering from the old battery radio
schematics to figure out the capacitors and resistors to use in the
audio circuits to make the output sound good. I'm basically too lazy
to learn the formulas to do my own calculations. The set sounds as
good as any battery set that I have ever heard.

This particular combination of a 1H5GT first audio stage tube followed
by a 1C5GT second audio tube was used in a lot of battery sets. It
also made selecting the output transformer easy to maximize output to a
4 ohm speaker.

Dan