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Author Topic: So You Want To Build A Beacon - My Gongshow  (Read 1538 times)

Offline 737999

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Re: So You Want To Build A Beacon - My Gongshow
« Reply #15 on: July 20, 2022, 0439 UTC »
Hello internet,

I'm a bit pressed for time tonight, but wanted to quickly post this up.

I've built a better keyer for the Rpi/Arduino beacons, using a simple off-the-shelf part. It's called a "High/low relay"


I have no idea what the science/tech behind it is, but it works way better than using wires and electrical tape. It took me far too long to figure out how to wire it up. So to save you the headache, here's my MS Paint diagram showing my final (working) result:

Here it is in action.

I know it works, as I tuned my shortwave radio to 7.023 and picked up the CW. Unfortunately in my area today, 7.023 has a constant whine/beep tone going on. Couldn't tell you why it's there, but it is. So when I tuned one of my other HF units to 7.023, thinking I'd pick up the Pixie beacon and its CW tapping, instead I got a loud and constant beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep. So that sucked.

Hoping I don't need to do a crystal swap for this to work, but that's a problem for a different day. The point is that we now have all three things solved for the Rpi beacon:

-- The Signal (From the RPi via beacon.py python script)
-- Feed the Signal (RPi keyer via relay setup)
-- Transmit the Signal (Pixie receives The Signal via the relay, and blasts via speaker wire antenna.)

So, technically the beacon is built. Now it's a matter of getting the beacon to consistently and repeatedly transmit, along with building the off-grid support (solar, battery, etc.)

« Last Edit: July 20, 2022, 1525 UTC by 737999 »

Offline 737999

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Re: So You Want To Build A Beacon - My Gongshow
« Reply #16 on: August 12, 2022, 1220 UTC »
Hi internet,

Bit of a time delay, as I had to wait for a few different transceiver units to arrive from the interwebs. Finally had everything arrive a couple of nights ago, and started tinkering.

I was hoping to finally get the basic Arduino beacon working, pairing the Arduino with a pre-assembled "Forty-9er" transceiver. Conceptually, I was hoping for the following:

-- Arduino sends digital CW message to Relay Switch contraption.
-- Relay Switch converts the Arduino message to something the Forty 9er can read.
-- Forty 9er receives relay data and transmits CW message.

The good news is that (1) The Arduino code works, and creates CW messages no problem. (2) The Forty 9er unit also works, and puts out (just barely) 1 watt of power. So I have a working Arduino, and a working transceiver.

The bad news is that the relay switch is messed up somehow, and I couldn't get the Arduino and Forty 9er to talk to each other. Figured that out when I did the following in exactly this order:

-- Hooked up relay switch to unpowered arduino.
-- Hooked up the Forty 9er to 12v.
-- Plugged in the relay's 3.5mm jack to the Forty 9er.
-- Powered on Arduino. <- Didn't get to this step.

I didn't have to actually power on the Arduino, because as soon as I plugged the Relay Switch's 3.5mm jack into the Forty 9er's "key" port, the Arduino powered on all by itself...  ??? Fortunately I didn't fry anything.

So I got the voltage tester out and started poking stuff. Best I can tell, the Forty 9er's key port has a constant 12v to "Tip". In fact all the Chinese kit radios I ordered appear to be wired this way: the 3.5mm tip gets non-stop 12v to it. I'm sure smart radio people knew this already, but I'm not one of those people, unfortunately for me. What I do know is you probably aren't supposed to power an Arduino with direct 12v, let alone do it through a keyer jack...

I guess I now need to figure out a different way to wire the relay switch contraption, because whatever I had wired up before won't work. Not even sure where to start on this. I've read that "Straight keys are just a short to ground", so I'm assuming I have to mess with Ground somehow.

Anyway, was a bit bummed at the results last night, but I'll hopefully get this sorted out.


Separately, I've got all the components together for a digital-mode beacon, so that'll be written up here later. Fortunately this one is a little easier - Everything is plug-and-play, other than having to write a little bit of code.

« Last Edit: August 12, 2022, 1224 UTC by 737999 »

Offline 737999

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Re: So You Want To Build A Beacon - My Gongshow
« Reply #17 on: August 13, 2022, 0239 UTC »
Hi internet,

Well I fixed the keyer issue. And now feel dumb. I guess why I couldn't figure my way through this was because I have a background in old cars. So "Short to ground" means sparks and welding stuff and fried electronics. Turns out in radio, that's exactly what you're supposed to do I guess: short to ground. Solution = wire up the keyer relay as follows:

What happens in the above circuit is every time the Arduino pulses Pin 13, the relay "connects" ground to the 12v coming through the 3.5mm tip. This keys the Forty 9er. I'm sure the real radio guys out there are shaking their heads at my amateur-hour nonsense, but even to a dummy like me, connecting a red wire to a black wire is a strange way to do things...

Anyway, after getting that sorted, I was able to assemble all the various parts I've accumulated and get a test unit built:

Everything appears to do what it's supposed to. Solar controller does its thing, the low-voltage cut-off does its thing. Arduino seems to bang out CW on the correct schedule. So I'd say proof of concept is good to go.

I've got a bunch of stuff to do tonight, so I'll save the full write-up/how to for later this weekend.

Thinking ahead, I'd love to have the Arduino run the back end of a telemetry beacon, but I'm not smart enough to code that. Over on the Raspberry Pi platform, I've assembled enough code to patch together the workings for a telemetry beacon, so that'll be next. The Arduino would be preferable though, as it consumes 1/3 the power that a Pi does. But as that Clint Eastwood dude said "A man's gotta know his limitations."

« Last Edit: August 13, 2022, 0245 UTC by 737999 »

Offline Teotwaki

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Re: So You Want To Build A Beacon - My Gongshow
« Reply #18 on: March 15, 2023, 1819 UTC »
Any updates?
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half


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