Connecting SkyDemon to a Trig/Funkwerke radio

For anyone wishing to upgrade their radio to take advantage of the latest SkyDemon addition whereby you can tap a frequency on the screen, and it sends it to your radio standby function without having to manually select it on the radio (shaky fingers in flight), here is the procedure.

This is for a TRIG TY91 radio that comprises 2 parts: The main VHF head and separate panel controller.

The Funke type ATR833 is an all in one unit and on a recent install we found a separate 9 way D data connector on a flying lead which you plug the BT578 module directly in to. Note you will still require power in for the BT578 module via a USB 5V source. Cable comes with it.

If you cannot locate a separate data cable, then it appears to be pin 9 (RS232 data in) located on the main 25 way D connector on the rear of the unit. WARNING: Do check the wiring pin out for your model of radio to confirm correct pin for data and 0V. As stated further on you can pick up a 0V from a more convenient point if required.

You require an RS232 module (IRXON BT578 V3 RS232 serial port Bluetooth adaptor) obtainable from AliExpress for around £23 inc postage (1 week delivery time).

Also required is a 9 way D connector (socket) from eBay, https://www.ebay.co.uk/itm/321481513060

Cost £2.79 inc postage

2 lengths of thin wire which you can twist together, ideally 2 different colours, say red and black.

Soldering iron and solder, a couple of cable ties and a small bit of dual velcro adhesive backed.

The BT 578 module comes with a fixed 9 way D plug (male) which you plug your newly acquired 9 way D socket in to. (The spare male to female adaptor also supplied from AliExpress is not required)

You now solder the 2 wires to the purchased Ebay 9 way D connector.

Pin 3 is the RS232 Data out

Pin 5 is 0V

You now plug in your 9 way D connector to the BT578 module. It is a good fit but as the securing screws are likely incompatible then you should use 2 cable ties as shown to secure the items together.

Now find a suitable place as near to the radio as practical and secure using Velcro or Cable ties as applicable.

The 2 flying leads are now required to be connected to the rear of the radio.

If wiring to a Trig radio, you will note that it comprises of a main VHF radio module and a separate front panel controller. On the rear of the panel controller is a 15 way D connector. By unscrewing this you can get access to it and take off the top shell to reveal the already connected wiring. You now need to locate the 2 required pins

Pin 6 RS232 Data in

Pin 7 0V (pins 1,4,7 and 10 are all 0V)

With a standard Trig loom, the located pins will already have wires attached so you will need to trace them to their destination whereby they (should) be sitting without anything connected.

In the install that I recently did (Pipistrel Alpha) the wires were marked RS232. Although not to be fooled as one wire was RS232 data in and one data out. So, by checking continuity (resistance meter) between each pin and ground (0V) it was determined that there wasn’t a ground pin present. In which case the

ground required was taken from a nearby 0V buss and the other wire to the data in.

Should you not be able to locate the wires to their end you will need to splice the wires on to the already installed loomed ones at a suitable point.

The BT578 module has an internal (li-ion rechargeable) battery and on/off switch which you can power up on delivery. However, do not use this on your installation else the unit will be on all the time (not good) and be recharging.

Instead, just rely on the provided power cable which plugs in to a USB outlet (assuming you have one) else you will also need to obtain a fused inline 12V to USB (5V) out adaptor.

Now all being well make sure the switch on the BT578 is set to M (male) and the module has power then switch on your tablet or phone and set Bluetooth to be on. You should now be able to locate the BT578. Select this and it will likely say pairing not compatible; just ignore this and go to “connectivity” on the Skydemon app and find BT578; also select the confirm button “for use with radio”. And select Garmin radio.

All being well you are now good to go by pressing anywhere that you see a frequency on screen.

That little essay was based on a Trig radio; having fitted one to a Funke also, there was a 9 way D data flying lead connector already present that the BT578 module plugged in to and the whole thing worked straight out of the box !