Uploaded June 2025 | Updated September 2026, 12 minutes ago
Jake Graham, KC7WXD, built a 1 tube CW transmitter and experimented with both a link coupled tank circuit and a pi network in order to match the high impedance tube output into a 50 ohm load. It's what hams routinely did before transmitters demanded no more from from them than their microwave oven or toaster. The transmitter is built using a printed circuit board from the Antique Wireless Association, and can be purchased at the link below:
antiquewireless.org/homepage/pcb-item-12
This bare printed circuit board (PCB) can serve as a component of a 6AQ5 transmitter for operation by licensed radio amateurs. This printed circuit board component and the resulting transmitter are intended for experienced persons. The completed unit and associated components produce potentially dangerous voltages.
This single-tube CW crystal transmitter PCB is for 40m and 80m and it may work on other amateur bands or modes. Up to 8 watts RF output into 50 ohms, with a nice tone using good FT-243 or HC-49 (modern) crystals. Importantly, with proper tuning, harmonics can be -49dB at the output of a pi network.
This offering is for the bare PCB only and no other components are included. A representative parts list (with Mouser and Tube Depot part numbers) along with construction notes ship with the PCB. In addition, this webpage contains the schematic and several other resources, which are available for download (below), that may assist the builder. Nominal PCB dimensions: 2.9″ x 2.9″.
The cost of the parts mounted on the PCB (not including the tube, crystal or shipping) is about $10, more or less. You’ll also need to raid your junkbox for a B+ supply, heater supply, and parts for the pi network or linked-coupled output. If you don’t have a B+ supply, be sure to check out the AWA Regulated Variable High Voltage Power Supply PCB in the online AWA store.
Help us preserve the history of electronic communications by becoming a member of the Antique Wireless Association at: antiquewireless.org/homepage/join-or-renew-membership
Subscribe to the Antique Wireless Museum channel and you'll receive news of our latest video uploads.
Jake Graham, KC7WXD, built a 1 tube CW transmitter and experimented with both a link coupled tank circuit and a pi network in order to match the high impedance tube output into a 50 ohm load. It's what hams routinely did before transmitters demanded no more from from them than their microwave oven or toaster. The transmitter is built using a printed circuit board from the Antique Wireless Association, and can be purchased at the link below:
antiquewireless.org/homepage/pcb-item-12
This bare printed circuit board (PCB) can serve as a component of a 6AQ5 transmitter for operation by licensed radio amateurs. This printed circuit board component and the resulting transmitter are intended for experienced persons. The completed unit and associated components produce potentially dangerous voltages.
This single-tube CW crystal transmitter PCB is for 40m and 80m and it may work on other amateur bands or modes. Up to 8 watts RF output into 50 ohms, with a nice tone using good FT-243 or HC-49 (modern) crystals. Importantly, with proper tuning, harmonics can be -49dB at the output of a pi network.
This offering is for the bare PCB only and no other components are included. A representative parts list (with Mouser and Tube Depot part numbers) along with construction notes ship with the PCB. In addition, this webpage contains the schematic and several other resources, which are available for download (below), that may assist the builder. Nominal PCB dimensions: 2.9″ x 2.9″.
The cost of the parts mounted on the PCB (not including the tube, crystal or shipping) is about $10, more or less. You’ll also need to raid your junkbox for a B+ supply, heater supply, and parts for the pi network or linked-coupled output. If you don’t have a B+ supply, be sure to check out the AWA Regulated Variable High Voltage Power Supply PCB in the online AWA store.
Help us preserve the history of electronic communications by becoming a member of the Antique Wireless Association at: antiquewireless.org/homepage/join-or-renew-membership
Subscribe to the Antique Wireless Museum channel and you'll receive news of our latest video uploads.
