An NE612 is normally configured as a mixer/oscillator for a DC rx. But watch what will happen if input pin 1 is earthed via a 10 K resistor. The local oscillator will appear at output pins  4 & 5.

So the same chip can act as both as an RX converter and as a TX vfo to drive a buffer to a pa !

An idea for a very simple qrp transciever.

This circuit was designed to work in a direct conversion receiver. With the exception of a volume control, mute circuit, and filtering, this is a complete audio chain. The amplifier is designed for a 50 Ω input impedance, which makes it suitable to follow a diode mixer. Total voltage gain is nearly 100 dB, which will provide enough gain for a reciever that contains a mixer with conversion loss. The final stage provides more than enough power to drive headphones, and might be capable of driving a small speaker.

Used with Permission from Craig LaBarge WB3GCK (c) 1996 - For portable QRP work, I often use either an end-fed half-wavelength wire or a quarter-wavelength wire for an antenna. A simple "L" network (with the antenna attached to the capacitor side) provides a good match for a high-impedance load, such as a half-wavelength wire. A series L-C circuit can be used to match a low-impedance load, as presented by a quarter-wave wire. I wanted to build a simple tuner which could be optimized for either situation with the flick of a switch.

As ham operators, we like to broaden our horizons by trying something new. There is nothing more satisfying about this hobby than building your own transmitter. The circuit in figure 1 is a crystal controlled CW transmitter with at least 5 watts of power. (The prototype generated 7 ½ watts) This circuit was built on a Radio Shack universal board (276-168B) and worked extremely well the first time on the air.