ΜBITX

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Notes on µBITX assembly and use.

Assembly

Parts that took some time to decide on approach to:

  • Case: used a cookie tin as a case.
  • Mic assembly: TODO

Still planned:

  • check power output on various bands
  • get on the air!

Antenna setup

Inverted V dipole made with Amateur Radio Supplies 20m dipole antenna wire (two 18' strands, trimmed, wrapped around insulators, strung up in attic) and 450Ω window line.

  • Originally was sent two 16ft strands, which is really too short. Customer service was great and sent me the 18ft strands and a prepaid return envelope for the 16ft strands.

QRPGuys Multi Z Tuner

QRPGuys 12W dummy load

  • Items from QRPGuys took about 2 weeks from date of order to arrive.

Mods

Applied during assembly:

  • Added a fuse before diode (succeeded, afaict)

Attempted after tested working:

  • Mitigating heat on LM7805:
    • Added a small 5V switching power supply before LM7805 (failed; created too much noise)
    • Relocation of LM7805 to case (succeeded, but got leads switched the first time and smoked the nano)
  • Dim LCD (failed—no effect)

Plan to attempt at some point:

  • TX LED
  • SWR meter
  • Red-on-black display (for night-time operation)
  • Foot-pedal controlled TX
  • Some sort of audio pre-processing?
  • Leveling out power?
  • Fix filters??
  • Use CEC firmware