This compact radio was constructed quite a few years ago, it has proven very reliable and performs very well. It covers 4,.5 to 13.5 megs, AM and SSB. Controls left to right are ATT, fine tune/clarifier, IF regeneration, and main tuning at the top, using a slomo drive.
After the attenuator control, the signal arrives at the 1st grid of V1, this is an ECH 84. The triode section is configured as a semi Vackar type oscillator, this type gives a relatively consistent amplitude over large tuning ranges.. L3 is the main regenerative IF coil tuned to around 1700kC, here I used a AM BC oscillator coil. The cathode of the detector is tapped down via a capacitance divider to provide feedback. The high IF frequency suppresses image responses at the higher received frequencies. The audio output stage uses the triode section of the ECF80/6BL8 . Regeneration is controlled via screen grid voltage on the detector. Audio output is very loud in headphones, but not quite enough for comfortable speaker listening. Sensitivity is around 5 microvolts, limited largely by mixer noise. The radio draws 800 mA from a 12 volt supply.
Edit. I forgot to draw in the fine tune capacitor, this is a 30pF variable that is paralleled across the 820pF padder in the oscillator section..
