Morse transmitter

AFAIK you can still buy the little hand held CB sets - some have a key and the code on the body.

Try Radio Shack.

If you use a traditional code transmitter, you'll need to have a receiver with a BFO, a Beat Frequency Oscillator, so you'll hear a tone in the receiver rather than just a thump.

That means either a special receiver, or adding a BFO to it.

But if you use an AM transmitter, and instead of a microphone feed an audio oscillator into it (turning the audio oscillator on and off with the code key), then any AM receiver will work. Whatever the tone at the transmitter, you will hear that in the receiver's speaker. This would work for FM transmitters, too.

So if the project is to teach code, or demonstrate it, you can use any "wireless" microphone type transmitter, and feed a keyed audio oscillator into the microphone input. Then use a regular broadcast receiver to receive it. All those adaptors they now have to connect MP3 players to existing radios would work too, just feed the audio oscillator into the audio input of the adaptor.

There was a time when cheap 27MHz (and later 49MHz) walkie talkies would include a button to send code, complete with the morse code chart on the cover, and they all used the same principle.

If you actually want to build the transmitter, then it shouldn't be hard to either find a schematic that includes such an audio oscillator from a time when that sort of thing was common, or any "wireless microphone" schematic and add an external audio oscillator.

Michael

Hi Michael,

Thanks to you and the other OP who replied. I did a google search but the top two sites were unobtainable :-(

I'd like to have a portable transmitter so it'd be a bit more fun for the kids -- not to mention grown-ups ;-) I'd like something that resembles equipment issued during WW2 -- with modern circuits instead of valves, though. I guess I'm probably looking for a DIY kit.

news:rec.radio.amateur.homebrew

Spanny Gobuck wrote in news:45352b54$0$5574$ snipped-for-privacy@news.astraweb.com:

My favourite:

Possibly the ultimate modern equivalent to the POW radio?

If you get it working well, you'd have to think about licensing, it is powerful enough to upset someone, somewhere, if you aren't careful.