A Modular Transverter for 3cm

This is a project that has been in the pipeline for a long time. Also it isn’t actually mine. For some time, my good friend Alan, GM0USI had been ‘collecting’ the necessary modules designed by Chris Bartam, GW4DGU. Alan is no stranger to 3cm and already has a fairly ‘potent’ portable system for that band. I, having regressed into the realm of thermionic valves lately, suspect that this ‘second’ transverter is Alan’s attempt to entice me to go out portable on 3cm occasionally.

For those unfamiliar with Chris’s modular transverter design, a breakdown of the system can be found here. I will admit that when Alan approached me and asked if I would would be up for building this transverter, I was quite excited. Actually I think what Alan actually said was “I have another wee job for you”. The modular design actually lends itself to innovative construction and I initially thought about a cube construction with each of the modules occupying a ‘face’. Whereas that is undoubtedly possible, it isn’t really practical. So for a few weeks Alan and myself mulled over various layouts and ergonomics. The main prerequisites were that it should be small (and light) and be interchangeable with Alan’s other portable microwave transverters. i.e. it had to fit onto Alan’s portable tripod and be waterproof.

This is what we came up with …

The photograph on the left is actually quite far on in the build but it does give an idea of the concept. Chris’s use of standardised module dimensions made stacking a logical option. Four of the modules are identical in size but it wouldn’t be practical to stack all four. Top-left in the photograph we have the distribution board mounted on top of the 2m IF interface board. Top-right is the Up-Down Converter module. Bottom-right is the 40MHz Reference Oscillator mounted on top of the 10GHz T/R board. Between the Up-Down Converter and the T/R board is the 10GHz Bandpass Filter.

The 2W 10GHz PA is mounted on the side-wall of the enclosure. At time of writing, Chris has not made available a matching 10GHz RX Pre-Amp so Alan provided one by DB6NT. The coaxial relay is a 12V fail-safe type driven from the distribution board.

Ideally we would have liked for ALL the connectors and switches to be mounted on the bottom face but space was limited. Left to right the connectors at the bottom are … 10GHz (SMA), 10MHz from GPS-Locked source (TNC), 144MHz IF (N-Type), 12V DC (XLR)