microT2 - $90

The microT2 is a replacement for the T2 transmitter module, and will also be a companion SSB exciter for the microR2 receiver.  An article on the microT2 was published in the December 2006 issue of QST.

The microT2 is a crystal controlled phasing type SSB exciter. By setting  the appropriate connections on the board, the microt2 can generate LSB, USB, DSB, AM, NBPM and CW signals. Details are provided in the sidebar on the second page of the article.

 The kit comes for 40 meters with a 7.285 MHz crystal (the QRP SSB calling frequency). A quality variable capacitor is supplied with the kit to be used in series with the crystal to provide some ability to "rubber" the crystal frequency a KHz or so.  Frequency stability of the VXO is quite good. Start-up drift is around 2 hz at 7 MHz  The PC board is designed so that it is easy to insert a signal from your external VFO or local oscillator,  or add a frequency multiplier to provide coverage on other bands.  When KK7B finishes his series of QST articles you should be able to build a microT2 for any single band from 160 - 6 meters.

A pair of TUF-3 mixers are used as the I and Q balanced modulators  They supply good carrier suppression without adjustment. IM products  in the opposite sideband are more than 30 db down at the exciter output.

The RF amplifier is a common-gate JFET.  It provides a very clean 0 dBm (1 mw) SSB signal. The output signal meets FCC regulations for direct connection to an antenna.

There are only three adjustments to set up the microT2 - Amplifier Tuning, Amplitude Trim, and Phase Trim. They are all set using a noise source (like noise from a receiver audio jack) into the micro T2, and then monitoring the microT2 signal in another receiver while making the three adjustments.

Links to Kit documentation:
Introduction
Construction Notes
Schematic and Layout
Parts List
 

Photos will be posted as soon as I take some!