[Boatanchors] Cheap & Easy Selectivity

[Ian Wilson]

Ed, thanks for pointing this out. I'd noticed the Super-Gainer before in the
early Radio Handbooks, but had never really studied it.

The lineup is like this:
  - pentode RF amplifier/mixer with regeneration to improve gain/selectivity
  - triode heterodyne oscillator
  - 456kc IF transformer
  - triode detector with cathode regeneration
  - triode audio amplifier stage

Regeneration in the RF amplifier is by feedback from the cathode to a tap on
the coil (like a Hartley oscillator). The level is controlled by
varying the screen
voltage. LO injection is to the suppressor grid of the pentode.

Regeneration in the detector stage is obtained by lifting the bottom end of the
secondary of the IFT (connected to the detector cathode by a bypassed resistor)
from RF ground. This is done with a potentiometer with an RFC across it.

This is a pretty nice design, with the regenerative detector being
isolated from the
antenna.

73, ian K3IMW