Modified MRX-40/Tuna Tin 2 Combination

Making it a "Real" Transceiver - By Dave Fifield, AD6A

I can report that I have made several mods to the TT2 and MRX that now result in a really nice usable rig. It has the following specifications:

- 500mW output into 50 Ohms (clean enough now)

- TX frequency variable from 7040.55 to 7042.03KHz

- varicap tuned (1.48KHz range)

- TX output envelope wave shaped

- Very little TX chirp (still a tiny bit, but I'm working on it!)

- RX tunes 7038.47 to 7042.72KHz (4.25KHz range)

- RX can hear -120dBm signals

- Full electronic QSK

- No relays, no switches

- No thump!!!

- Real sidetone (clean sine wave)

The schematic is here

Here are a few photos of my MRX40/TT2 combo - note, the mods are all done on the underside of the PCB's so that they still look original - you can just see the mods on the MRX40 side-on view.


(Click on any image to see it in high resolution)



72, Dave Fifield, AD6A






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