The Quartzmite project started when I decided to build a surface mount version of the popular 'Rockmite' QRPp CW transceiver. After talking with Dave Benson, K1SWL the original designer and Chuck Carpenter, W5USJ who did some efficiency modifications to the P.A. and low pass filter I came up with a variant of the circuit that uses nearly all SMT parts.

As well as the improved Tx low pass filter my designs make use of the second op-amp in the LM1458 to implement a Sallen-Key second-order active low pass audio filter for the sidetone, making it sound much less harsh than the square wave of the original Rockmite. I've also put a pre-set pot in the sidetone circuit so the user can set the sidetone volume independently of the Rx audio.

There have now been two itterations of the project.

The first version was mainly an SMD build of the original RockMite incorporating many of the 3rd party modifications that had already been designed. A board level kit was made available and several were built by QRP enthusiasts. See here A V1 Quartzmite in it's Altoids tin

The second version has several more features. There is a new keyer with additional features including memories. The Tx/Rx audio switching and receiver muting is now controlled directly from the microprocessor to allow sequencing. The Tx/Rx offset mechanism is completely new and the varicap diode control voltage is now generated from the microprocessor via a D2A converter to give better control. See here The V2 Quartzmite production prototype