SCHEMATIC ONLY 12AL8 SINGLE TUBE QRP TRANSMITTER/REGEN RADIO 160/80/40 METER CW

Description

This is a hand-sketched schematic only for the radio described below. No parts are included, but all parts values for the circuit are shown on the circuit drawing.
While I'm always willing to answer questions on the radios that I make, you will be on your own, as to how you construct this radio.
So this is not a step by step manual, but simply a hand draw schematic, along with  all the component values (nothing else).
I make many of my radios just for fun. This circuit uses a single tube 12AL8 space charge tetrode for the transmitter, and the triode section is the regen detector. There's also a single stage transistor audio amp for increased headphone volume.
Frequency coverage for the receiver, with coils provided, is from the top end of the broadcast band up to about 13 mhz, shortwave. The cw transmitter works on 160, 80 and 40 meter cw.
Power output of the transmitter is only about 100 milliwatts, with battery power. You can get a little more output if you power the circuits with external dc voltage. The way I have everything wired you can use either batteries (as shown in the pics) or dc voltage from external power supplies. You can even charge the filament battery pack while using the radio.
I planned it this way because the 12AL8 filament requires 0.55 amps of dc current. This means that the battery life for the 16 volt 4x series 18650 batteries is only capable maybe 45 minutes before you have to recharge the batteries. The 2x 9 volt batteries should run for days before needing a recharge. Total dc voltage for the plate circuit of the transmitter is around 32.5 volts.
You can power this radio with 2 external supplies, in lieu of batteries. In that case, you need one source of about 15 to 16 volts for the filament circuit, and a second supply of 18 to 25 volts for the transmitter plate/regen detector circuits. Within the circuit, these two supplies are connected in series. The 12AL8 filament will take most any voltage, within the range of 12.6 to 15.9 volts.
You will need a hi-z headset for the radio (2 to 4k ohms). Piezo headphones will also work.
The circuit has a send/receive switch, so you need only one antenna for this QRP transmitter-receiver.
Mailing to the United States only.