Thursday, June 25, 2009

back to radio... the AxeMite

Recently a book was obtained, "More QRP Power", which proved itself being a source of inspiration.
The design I'd seen on the internet before, but now, RockMite and HiMite really jumped at me.
Being myself an occasional user of straight-keys, I miss this opportunity in Dave's design. Additionally I personally could appreciate a CQ-routine performed by the micro-controller. I agree, it would be somewhat to much to ask from a 12F509. Thus, I dropped Dave's design and kept the all over idea in mind.
It seems appealing to me to use HCTTLs at some stages, e.g. the oscillator (74HCT01), switches (74HCT4066) etc.
As to the functionality of the controller, this is what I believe it will be at the end:
  • dit and dah ports open when powering up => iambic keyer
  • dit port open, dah port closed during power-up => straight key
  • dit port closed, dah port open => Vibroflex-style (short dit, undefined dah)
  • both ports closed => ... (don't know yet, maybe keyer-speed)
  • one control switch, for reversing (à la RockMite) and CQ-ing
  • side-tone generated by the controller (à la RockMite)
I think, I can squeeze that into a PICAXE 08M...

Considerations about the programming:
  • ElBug by the "tone" command
  • straight-key side-tone by "pulseout" and "pauseus" commands
  • control-button short push: reverse rit/xit
  • control-button long push: CQing
The present trick about the straight-key is, that the insertion of the same will short the dah-port, thereby enabling the straight-key-mode.

As for rit/xit or tuning (à la HiMite), the PICAXE 08M opens the possibility of pseudo D/A-conversion by means of PWM. Range and digitisation is such a setup would be not the best, since of 256 different voltages can be generated. Some experimentation will be required to answer the question of the usability of such a design.

As soon as there is something to show, I will publish it on my webpage.

73 for now...