Shop OBEX P1 Docs P2 Docs Learn Events
Tips for wiring prop to ham radio for sending morse code — Parallax Forums

Tips for wiring prop to ham radio for sending morse code

DeskguyDeskguy Posts: 32
edited 2012-01-01 12:58 in Propeller 1
Hi,

I have a ham radio that I want to connect to my prop for sending out morse code, through the key jack in the back of the radio.

The attached image is from the radio manual. I have a stereo plug and want to do the wiring like the diagram on the right. The radio has a built-in electronic keyer (it will make the correct length of dot and dash based on the radio settings).

BTW, the radio model is Yaesu FT-817.

Any suggestions?

Has anyone tried this and can point out any 'gotchas' that I should avoid?

Thanks!

David
key-wiring600.jpg
600 x 359 - 43K

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-12-31 10:04
    The safest way to do this is with a small relay or optoisolator. Be sure to configure your transceiver for straight key operation and form the dit/dah timing with the Propeller. Otherwise, it would be virtually impossible to synchronize the Propeller with the FT817's internal keyer.

    -Phil
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-12-31 11:46
    An opto, reed switch or relay would certainly be safer and avoid any ground loops.

    Alternately, I would try using one or two prop outputs with 10K series resistors (because that is easy). Just use the prop as an open collector output(s) - that is, make the outa=0 and switch the dira=1 to output "0"=GND and dira=0 to output "open". I would suspect there would be some form of micro/gate in the radio with some protection anyway. If it works, then drop down to some lower value resistors like 4K7 or 2K7.

    As Phil suggested, the diagram on the left would be easiest for the prop to control. You would require more complex code for the diagram on the right because effectively you would have to calculate all the timing in the prop anyway. You can still use a stereo connector, just wire the key to the dot (tip) and ground to the dash and common.
  • DeskguyDeskguy Posts: 32
    edited 2012-01-01 05:03
    Hi Phil & Cluso,

    Thanks very much for the tips - definitely a bit more involved than I had first expected - glad I asked.

    Appreciate the help.

    David
  • LeonLeon Posts: 7,620
    edited 2012-01-01 05:48
    I've got an FT-817, but haven't tried that. The FT-817 Yahoo group is the place to get answers.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-01-01 09:17
    I looked at the FT817 schematic. The key input jack's shell is grounded, as one might expect. The DOT and DASH inputs pass through 1K and 10K series resistors, then into the main microcontroller. I did not see any pullups, so they must be internal to the micro. Although it might be possible to connect the Propeller directly to the DOT input and ground, consider that the transceiver costs north of $800 to replace and that a small relay or optoisolator might be another buck or two for the extra security. The math seems pretty simple to me.

    -Phil
  • DeskguyDeskguy Posts: 32
    edited 2012-01-01 09:43
    Yup - that is what I was thinking as well. Hate to mess up an expensive radio by mistake :(

    Appreciate the tips!

    David
  • Cluso99Cluso99 Posts: 18,069
    edited 2012-01-01 12:58
    Use an opto like a cheap 4N28. You only need 1 since the prop should generate the timing like Phil said. You are only going slow relatively - cheap insurance and simple to do. Just like driving a led from the prop side.
Sign In or Register to comment.