I made this regen radio/QRP cw transmitter with a new AC-1 chassis. It uses two 6V6 pentode tubes with a 12 volt inverter power supply.
The construction and operation are a bit old analogue nostalgic, akin to something you might find from the 1950's era. Frequency coverage for both send and receive spans the 630, 160, 80 and 40 meter ham bands, accomplished with plug-in coils. I will include one QRP crystal for each band. All I have for 160 meters are the 49/U crystal types, at 1843 khz.
The transformer shell on the chassis is not real, but a 3D print, painted black. Inside lives the little 12 volt inverter transformer, which uses two NPN transistors to produce over 300 volts, no load dc voltage. It will produce around 175 volts dc, under load.
Even though the radio requires only a 12 volt power source, plus an internal 9 volt battery to operate, it is still just as lethal as any similar circuit that is powered by 117 volts ac from the wall socket. Please do not purchase this item if you are not accustomed to working around high voltage. Like most any vacuum tube ham radio transmitter, it can kill you if not handled with proper respect!
RF QRP power out from the transmitter is about 3 to 4 watts on 630 and 160 meters. Around 2.5 to 3 watts output on 80, but as is typical of the old 6V6 audio tubes, power will drop off to a watt or so on 40 meters.
When the receiver alone is powered on the current requirement from the 12 volt dc supply is around 600 ma, but needs about 2.5 amps when in transmit mode. The high voltage supply turns completely off with the send/receive switch is in the regen receive only mode. One front panel switch takes care of switching the antenna, power on/off, and audio mute when in transmit mode.
Standard 1/4" jacks are provided for a cw key and headset.
The receiver works well, but of course will not compare with a $400 communications receiver. The circuit has a one transistor built-in audio amp for increased gain.
You'll need high impedance headphones for the receiver, either the old standard 2 to 4K ohm inductive types or a headset using Piezo elements. Headphones and batteries are NOT included in this listing.
The transmitter employs a Pi-network for the RF output, with one tuning control. The antenna load side of the network uses fixed capacitors which are built into the plug-in coils. The large dial on the right side of the front panel is for the receiver tuning. The regen control-on/off filament switch is located on the top left side of the chassis.
I will provide a hand sketched schematic diagram of the circuit, when this item is purchased.
Checked out and guaranteed to be in working order when shipped.
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