Blue Dmod
A Bluetooth audio interface for Ham radio Digital modes like FT8, SSTV, RTTY and more. A DIY Kit with lots of customization options. Choose your own 5VDC power, I/O connectors.
Block Diagram:
V1.1 rev1.3 have fault free PCB “Size:60x60mm” which were in V1.1 rev1.2. Once assembled you can choose whether to power it up straight from 5V (USB/Power bank) have a 5V out battery. I have tested few 3.7V battery charge and 5Vboost circuits but as they have a low current shutoff didn’t work out as they shut down after 10 seconds of boot up. My work around is to buy a cheap power bank which are typically sold at local grocery shops for £5 to £10 they don’t have any low current shut off circuit. I had to remove the casing of power bank to fit in my box which is 115x90x55mm.
How it works:
Audio from Radio (from I/O pin1) is sent to Bluetooth Mic input. Audio from Bluetooth Left channel is used to send data to Radio on I/O pin 2. Audio from Bluetooth Right channel is sent to Pro micro via voltage divider. Pro micro is programmed to sense the voltage rise from Right channel. Once volage cross the threshold PTT is triggered on I/O pin 3. PTT is stay on till the voltage get blow threshold. You can set the time of PTT trigger via 10K pot or default at 1000 ms (2 separate programming files provided).
I/O connector:
You can choose your own connector for I/O from RJ45 Port, GX12, M12 or anything that works for you.
Operation:
Paring (first time):
Make sure radio is not connected with Blue Dmod. Turn on Blue Dmod, on your Smartphone/Tablet/PC turn on Bluetooth. Blue Dmod will show up as “Bluetooth Audio”. Pair it with your device (PTT will trigger once or twice as the Bluetooth have built in sound with triggers the PTT).
Normal operations:
Make sure the radio is not connected to Blue Dmod and turn on the Blue Dmod. PTT will trigger once or twice due to Bluetooth’s internal audio for bootup and connecting toa device. Connected the Radio. Open the app/program you want to use make sure the volume know on the radio is adjusted to proper volume. When you will send data from the app Blue Dmod will automatically trigger PTT of the radio for transmission.
Schematics:
PCB:
Gerber File, BOM and Programming files:
You can Download Gerber and BOM from GitHUB.
Photos internal:
BOX Photos:
Blue Dmod Connected to Wouxun KG-UV9D:
Known Issues:
PTT keep getting triggered:
If Blue Dmod is placed next to Antenna port, the tx radiation might trigger the Blue Dmod on its own until powered off. Also, if the I/O cable is long and is next to transmission line/ antenna it might show abnormal behaviour.
73’s