ARROW uBITX Group Purchase

Things related to the uBITX radio group purchase made by a number of ARROW members.

Huge resource page by ZL1AXG: http://ubitx.net/

Problems, Issues and Glitches - significant issues reported by builders

• TDA2822 stereo amplifier high failure rate
  • Reported on the mailing list, Some ideas discussed there:
    • Replace with 8-pin socket and NJM2073D
    • LM386 + adaptor
  • <link(s) to best discussion(s), fix(es), etc(es)>
• Power output differences across bands
  • http://ubitx.net/fix-fix-uneven-tx-output-across-bands/

Building Hints and Tips

Recommended Mods

• KD8CEC software
  • http://www.hamskey.com/

Advanced Mods

• AGC circuit
  • K9HZ summary of options
    • ... audio range passband...Benefit: saves your ears, $0.02 diode, trivially easy to implement.Bad: only protects your ears... not RF sections from excessive signal and overload. Not a true AGC signal for "s" meter, only an audio strength.Comment: Save the $0.02 diode, turn the damn volume down and live with the IF overload.
    • ... IF range passband...Benefit: Saves ears, prevents IF overload, AGC signal for "s" meter (can be calibrated to real signal strength by reference).Bad: More complicated/ more parts, RF level attenuator and AGC response, more expensive than the $0.02 diode,Comment: can be triggered by anything in the passband and that can be good and bad.
    • ... Full range integrated Passband (front end through audio section)...Benefit: True AGC on all levels, no overload or distortion of any stage. AGC signal for "s" meter (can be calibrated to real signal strength by reference).Bad: Very complicated, impacts every RF/IF/Audio stage. Lots of mods and parts.Comment: A CW ops dream.
• KD2NDR port to Teensy

Enclosure Ideas

ARROW Rig Showcase