Check the listing for details. SCHEMATIC ONLY OF THIS ULTRA SIMPLE 6V6 QRP 160/80/40M CW TRANSMITTER. Condition: Used. Listed at 10.95 USD. THIS LISTING IS FOR THE SCHEMATIC ONLY, with parts values specified. No manual or step by step instructions are included in this purchase. You can't beat this design for simplicity. A single tube 6V6 cw transmitter, with just a switch and one control on the front panel. Once properly adjusted, with the single front panel control, it produces a real nice cw tone. The transmitter in the photos was constructed in the pine wood slat board style, typical of similar items found in the 1930/40's era. Polyurethane finish was used for the wood surface. The power requirement for this circuit is a single 6 to 7 volt dc source, capable of providing about 2 amps dc current, when transmitting. This can be either a bench top dc supply or batteries. A single front panel switch provides power on/off, standby and transmit functions. In standby mode the filament only is turned on, with just over 1/2 amp current drain. Switching to transmit provides instant dc voltage to operate the 6V6 transmitter circuit. In standby mode no high voltage is being produced by the inverter power circuit, which employs a 6.3 filament transformer, driven by power transistors. In key down transmit, the dc power supply voltage drops to about 150 to 155 volts dc. This is quite normal. Depending on the band and activity of the crystal used, the RF power out varies from about 1.8 to 2.25 watts. Not bad for a single 6V6, operating from a 6 to 7 volt dc source. Two coils are required for the 160/80 and 40 meter bands. I used a larger coil for 160 or 80 meter operation. A separate coil is required for operation on the 40 meter band. I was able to get good cw tone with the tall HC-49/U QRP crystals. The small HC-49's will work, but typically produce a slight chirp, simply because the smaller crystals do not have adequate power capability to handle much beyond a few hundred milliwatts. I guarantee my circuit design will work if properly constructed and connected to a power source and your ham radio antenna. A good earth ground is always essential for best performance. Again, this listing is for a schematic only. Nothing else is included.