julian814 wrote:
Well, I'm back. Still looking for a one tube regenerative receiver I
can build for myself. I did
manage to find a kit online that looks close to what I want - it's
called the Radio Ace kit.
Made to look like the old Radiomann sets they used to sell back in the
day, it looks nice,
but at $100+ it seems it was made for people with more money than
brains.

Back to the topic. I found the schematics for the Doerle Twinplex
receiver, which should do
the trick, with one exception - the tube it uses isn't one of the
tubes I have. I do have three
different twin triodes that are of more recent vintage, but I don't
know if I can substitute any
or all of them in the circuit. The are a 4BC8, a 6FQ7 and a 6BZ7.
Anybody have any ideas?


Ralph Glatt

Well the 4BC8 has a 4.2 600ma heater, it could run on 6v through a
voltage dropping resistor. It has a mu of 35 (both triodes).

The 6FQ7 is very similar to the 6CG7 (only difference is that the 6CG7
has an internal shield between the two triode sections). It has a 6.3v
600ma heater and both triodes have a mu of 20.

The 6BZ7 has 6.3v 400ma heater and a mu of 36 (both sections).

The 6BZ7 would probably be the best choice as it is the lowest power
version tube and has the most gain.

The parameters of a tube in this circuit are not that important, any
tube will work well. Adjustment of the grid leak resistor and capacitor
as well as the number of turns in the tickler coil in the detector
circuit as well as the cathode bias resistor in the amplifier circuit
will be necessary with a tube change, but even here the values won't be
critical. Anyway I'd use the 6BZ7.