AGC module for the popular QCX-series CW transceivers. This AGC module can be fitted to any PCB revision of QCX (classic), QCX+ and QCX-mini. 

https://groups.io/g/QRPLabs/topic/a_simple_qcx_agc/80821592

A control signal from the QCX can switch on/off the AGC. This requires QCX firmware version 1.08 or above, where the is a menu item in the, there is a menu item in the “Other” menu, If you prefer to keep the AGC always on, there are a pair of pads on the PCB that you can short with a solder blob, a small wire, or an 0603 zero-ohm resistor.

Firmware version 1.08 or above is required if you want to control the AGC On/Off via a menu item. This is why there is the option to add the QCX firmware upgrade chip to your order. If you already have 1.08 or higher, or if you want AGC always On, there is no need to add this option. 

On a QCX-mini Rev 3 (and above) PCB, there are 5 holes on the main QCX-mini PCB that line up exactly with the 5 holes on the AGC module. Installation is therefore exceptionally easy using 5 component lead off-cuts to make the connection between the two boards, and no other changes.

On other QCX-series models, all of which essentially share the same schematic, the principles of circuit operation are the same, but you will need to install wires to make the connections.