Auto-Keyer for Radio "Fox Hunting"

Attach an amateur radio to this and the radio will regularly identify itself so others can use their direction finding skills and locate it.

Jun 14, 2019

17168 views

11 respects

Components and supplies

5

Capacitor 100 nF

1

Capacitor 100 µF

1

Jumper wires (generic)

1

Toggle Switch, Toggle

1

Relay (generic)

1

External handset/mic plug for your amateur radio

1

Arduino UNO

1

LED (generic)

Tools and machines

1

Solder Wire, Lead Free

1

Amateur Radio

1

Soldering iron (generic)

Project description

Code

Fox Hunting Radio Keyer

arduino

The Arduino that keys up the radio to transmit and sends the Morse code to identify itself.

Fox Hunting Radio Keyer

arduino

The Arduino that keys up the radio to transmit and sends the Morse code to identify itself.

Downloadable files

Schematic for the fox hunt radio's keyer

Schematic for the fox hunt radio's keyer

Comments

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dephillipsmi

7 months ago

For this to properly compile with the latest version of the IDE you need to replace all char* reference with char const*

Anonymous user

2 years ago

Nanos must be quite robust. Programmed the Nano, hooked up a 5v relay and a small speaker. Powered it all up via USB and let it run for 3 days. Ran perfectly. Then I saw comments about the diode for the relay. Ooops, didn't have one of those in - but it's working. So, hooked up a radio and it all went wonky. Just did order up the caps to put in to prevent that known issue. Got 100 1N4007 diodes of the Zone of Ama for about $5.00 on the way. Sure won't hurt to toss one in there, JIC. Building up 8 of these for the local ham club - look to have some fun!

Anonymous user

2 years ago

Newbie... Please describe where I type my text to be sent.

nfarrier

2 years ago

It's in line 78 of the code.

Anonymous user

2 years ago

Could you please put a date on that schematic, so that people can see that you have addressed the latest comments? I saw a comment elsewhere that the diode is still back to front. VK3BT

nfarrier

2 years ago

I've updated the schematic. Sorry it's taken so long.

glennedi

2 years ago

Hi nfarrier You need a diode across the relay coil not a capacitor. When you power off the relay coil the magnetic field collapses and induces a voltage into the wire, it is this spike which is probably causing your Arduino to reset. Reference: https://electronics.stackexchange.com/questions/100134/why-is-there-a-diode-connected-in-parallel-to-a-relay-coil

nfarrier

2 years ago

Thank you. I made the change. The link was helpful. I also found a great demonstration of why they're important here: https://www.youtube.com/watch?v=5kjtiY9gxGM

Anonymous user

2 years ago

Love the project. The anti-spike diode on the relay should be reversed. They go in reversed biased, not forward biased. Forward biased = short to ground.

Anonymous user

2 years ago

What kind of Relay (generic) do you use? it's a 5 volt Relay?

Anonymous user

2 years ago

I would suggest you the following: a) Put an 1N4007 diode in parallel with the relay coil to cancel the high voltage spikes when the relay coil is released. b) Probably the relay coil can demand more current than the micro controller leg can sink, this can lead in a premature degrading or destruction of the uC. c) As a way to improve the circuit, most radios can be keyed using a simple transistor, avoiding this way the relay use, potentially extending the gadget battery life. 73's de YV1HX

nfarrier

2 years ago

Thank you. I made the change. In the comment above I put a link to the best demonstration of your point B. I though about your third point, but I wanted to make sure I completely isolated my circuit from the radio keying.

Anonymous user

2 years ago

Hi, I love this project so I built one but I can't figure out what I did wrong. It turns the radio on through the relay and I can hear it transmitting just fine except the morse code ID doesn't start until after the radio shuts off. I can see the arduino (uno R3) sending my call sign (by the led) but only after the relay shuts off the radio. Any help will be appreciated. Thanks

nfarrier

2 years ago

I realize this was a long time ago, unfortunately I didn't see a notification that you'd posted a problem. Are you still in need of help, or did you get it to work?

Anonymous user

3 years ago

Could you please put a date on that schematic, so that people can see that you have addressed the latest comments? I saw a comment elsewhere that the diode is still back to front. VK3BT

nfarrier

2 years ago

I've updated the schematic. Sorry it's taken so long.

Anonymous user

4 years ago

Nanos must be quite robust. Programmed the Nano, hooked up a 5v relay and a small speaker. Powered it all up via USB and let it run for 3 days. Ran perfectly. Then I saw comments about the diode for the relay. Ooops, didn't have one of those in - but it's working. So, hooked up a radio and it all went wonky. Just did order up the caps to put in to prevent that known issue. Got 100 1N4007 diodes of the Zone of Ama for about $5.00 on the way. Sure won't hurt to toss one in there, JIC. Building up 8 of these for the local ham club - look to have some fun!

Anonymous user

5 years ago

What kind of Relay (generic) do you use? it's a 5 volt Relay?

huntercf

5 years ago

Hi, I love this project so I built one but I can't figure out what I did wrong. It turns the radio on through the relay and I can hear it transmitting just fine except the morse code ID doesn't start until after the radio shuts off. I can see the arduino (uno R3) sending my call sign (by the led) but only after the relay shuts off the radio. Any help will be appreciated. Thanks

nfarrier

2 years ago

I realize this was a long time ago, unfortunately I didn't see a notification that you'd posted a problem. Are you still in need of help, or did you get it to work?

kmikemoo

5 years ago

Love the project. The anti-spike diode on the relay should be reversed. They go in reversed biased, not forward biased. Forward biased = short to ground.

Anonymous user

5 years ago

Newbie... Please describe where I type my text to be sent.

Anonymous user

5 years ago

I would suggest you the following: a) Put an 1N4007 diode in parallel with the relay coil to cancel the high voltage spikes when the relay coil is released. b) Probably the relay coil can demand more current than the micro controller leg can sink, this can lead in a premature degrading or destruction of the uC. c) As a way to improve the circuit, most radios can be keyed using a simple transistor, avoiding this way the relay use, potentially extending the gadget battery life. 73's de YV1HX

nfarrier

2 years ago

Thank you. I made the change. In the comment above I put a link to the best demonstration of your point B. I though about your third point, but I wanted to make sure I completely isolated my circuit from the radio keying.

glennedi

5 years ago

Hi nfarrier You need a diode across the relay coil not a capacitor. When you power off the relay coil the magnetic field collapses and induces a voltage into the wire, it is this spike which is probably causing your Arduino to reset. Reference: https://electronics.stackexchange.com/questions/100134/why-is-there-a-diode-connected-in-parallel-to-a-relay-coil

nfarrier

2 years ago

Thank you. I made the change. The link was helpful. I also found a great demonstration of why they're important here: https://www.youtube.com/watch?v=5kjtiY9gxGM