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

Description

THIS LISTING IS FOR A HAND DRAWN SCHEMATIC ONLY OF THIS REGEN RADIO/QRP TRANSMITTER.
The 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, as designed, 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. With the transmitter pictured I was also able to get it to load up on 30 meter cw, at the extreme limit of the 40 meter coil.
Other frequencies are possible if you care to wind the coils.
With this design, power output from 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 also run this circuit with 2 external supplies. One 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 chassis, 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.
I will provide a hand-sketched schematic, along with directions for all controls and connectors. Again, no manual or instructions are included. I will email or mail you my hand drawn diagram, which shows all parts values.
The chassis, panels, etc., this is all up to you. No parts whatsoever are included--just a schematic, with parts values indicated.
**************************SOLD TO US BUYERS ONLY (or mailed via the eBay international shipping option).......KW7T