Morse Code Headset Mod?

[user2000]

I would like to send Morse code over my PMR radios mostly for nerdy fun but I'm also curious to see what extra range is possible when I'm not trying to make out a human voice.

We have a pair of Binatone Action 1000 radios which have a 2.5mm audio jack to take a headset. My knowledge of headsets is limited but searching this forum I have seen posts where people are saying they use xbox live headsets on binatone radios with a simple 3.5mm to 2.5mm adapter - this makes me think headsets must be pretty standard?

Currently I am wondering in the direction of modifying a headset by cutting off the microphone and replacing it with a code key - though I expect things are not quite that simple! I need to learn a bit more hence the searching that lead me to this forum.

I am wondering if anybody has done anything like this already before I set out to reinvent the wheel? I don't own a code key yet, so for all I know they come with 2.5mm jacks attached - then I will feel very silly

Does anybody have any advice? I'm a physics graduate with a reasonable working knowledge of basic electronics and google so feel free to go all technical on me...

[M0AFJ]

Hi, A couple of things you will need to do, firstly you will have to key the PTT line rather than the mic, that way you will break the carrier produced by your set, you will have a problem as this really isnt a proper keying circuit and the actual keyed waveform will look strange with a slow rise time and fast decay and you will not be able to send at any speed, secondly unless the receiving station has a bfo (look it up), he will not be able to read what you are sending. you need to mix the received signal with a seperate signal to produce a tone, this is generally done at the IF stage. This tone would then be demodulated so you can actually read the morse sent.

Best thing to do is to get your Ham licence and use CW on the Ham bands..

Hope this isnt too waffley!

Tim M0AFJ

[northern35s]

And if you just pressed the PTT and sent a tone, it is just an audio tone, not much different properties to your voice when sent using FM.

[user2000]

Thanks for the replies.

My original idea was as northern35s describes - to send a tone the way I send my voice, probably by putting a tone down the microphone and using a key to turn the tone on and off to generate the code which would then be heard at the other end.

It's more for fun than to try and acheive great distances (this is pmr after all) and I might be able to do it with an mp3 player recording of 'beeeeeeeeep' and a simple switch. I thought if I turned off the squelch so I can hear constant static I might be able to make out beeps better than words.

However thanks to M0AFJ for suggesting the PTT idea which presumably is closer to how code is sent in the real world. There is, however, no way on earth I am going to be able to hack a bfo in to a pmr walkie talkie without some serious pain.

I notice that some kids toy walkie talkies have morse code buttons on, I wonder which way they do it...

[curny]

If you go on Youtube and key in 'pmr446 radio beacon', you will see a video at top of list by curny1 (me!) of a little experimental morse beacon i made for pmr446.

It might give you some ideas!

As you say, even doing it this way, morse can be heard above the static and read when normal vioice would be unitelligible.

The toy walkie talkie morse buttons that you mention produce a tone by a very rough method, essentially producing feedback from the speaker that is then sent

Curny

[Lightspeed]

Not sure the BFO route will work as the PMR Standard is FM?

We've played with morse over PMR446 by injecting a tone into the mike input in th eway you proposed.

Our systems use low cost chinese ( ebay) guitar tuneing gizmos that are able to tone generate to a headphone jack output. The output is fed to the PMR mike input with a morse key in one line to make/break the tone reaching the mike in on the PMR. This system allows keying high speed.

Range is slightly improved over that of PMR Voice communications.

Good luck and let us know how you get on