ATX TIMER (PIC16F84 or PIC16F628)

The ATX PIC timer is pin compatible with ON7YD 80m and 2m transmitter designs. It provides keyed CW on 80m units. On 2m units, the keyed output drives a separate tone generator (CD4093, NE555 or similar) for MCW.
The phono socket provides the only user port to the PIC in these transmitters, and is used for both synchronization and eeprom loading.
The 80m TX by G3ZOI uses ATX software.

TRO TIMER (PIC16F628 only)

The TRO PIC software controls the timer and also provides the audio tone for MCW (i.e. NO separate IC tone generator). The PIC directly switches the ICS525 clock multiplier. A tactile button on the PCB is used for loading a callsign into eeprom.
The 2m TX by G3ZOI uses TRO software.


  • Sends either MO+ E, I, S, H, or 5 for 1 minute or MO continuously at approximately 9wpm
  • Transmit cycle time either 5 foxes in 5mins (standard) or 2 foxes in 2 mins (training).
  • Delayed start from 30 mins up to 31 hours.
  • User programmable call sign sent at the end-of-transmission.
  • Transmits MOx once each cycle at 30wpm - 1 hour before the delayed start.

For the scout training version only.

  • Selectable 30 secs or 1 minute transmit time
  • Additional cycle times for 3-foxes and 4-foxes.
  • Maximum delay time reduced to 3.5 hours.


(right click to save)

© 2005-11 open-circuit.co.uk