09-06-2018, 05:52 PM
I spent a few frustrating hours **** around with the interface board I had knocked up. While the system works with the mixing board, sometimes RF gets into it and it goes crazy.
I appears that the headphones I was using to monitor things are themselves an antenna. A few turns through a toroid ferrite helped, until the cat decided to help and knocked the headphones off the bench, shattering the ferrite...
So still no joy with the DIY interface.
I have pared it back to a DIN connector, some cable, vero board with two 3k Ohm 1:1 transformers, some more cable, 3.5 mm connectors.
The Rx signal is quite low but gets from one end to the other. The Tx gets to the board, but not to the radio. I even soldered jumpers to bypass the transformer with no luck.
All that is left to swap out is the DIN connector and I don't have one to hand, a visit to Jaycar is in my future I guess.
Normally, at this juncture, I'd borrow a CRO and signal generator from work and start tracing. Unfortunately where I work these days doesn't have such things. (an unforeseen downside to moving to a less technical role I suppose).
Anyhoo, it has 'forced' me to order one of the little TFT LCD Oscilloscope kits from fleabay (https://www.ebay.com.au/itm/282873100082) for about $30. I have a couple of audio projects on the workbench, so it might be useful elsewhere. Other than replacing the DIN connector, I guess this task is on hold until I get and build the CRO.
I appears that the headphones I was using to monitor things are themselves an antenna. A few turns through a toroid ferrite helped, until the cat decided to help and knocked the headphones off the bench, shattering the ferrite...
So still no joy with the DIY interface.
I have pared it back to a DIN connector, some cable, vero board with two 3k Ohm 1:1 transformers, some more cable, 3.5 mm connectors.
The Rx signal is quite low but gets from one end to the other. The Tx gets to the board, but not to the radio. I even soldered jumpers to bypass the transformer with no luck.
All that is left to swap out is the DIN connector and I don't have one to hand, a visit to Jaycar is in my future I guess.
Normally, at this juncture, I'd borrow a CRO and signal generator from work and start tracing. Unfortunately where I work these days doesn't have such things. (an unforeseen downside to moving to a less technical role I suppose).
Anyhoo, it has 'forced' me to order one of the little TFT LCD Oscilloscope kits from fleabay (https://www.ebay.com.au/itm/282873100082) for about $30. I have a couple of audio projects on the workbench, so it might be useful elsewhere. Other than replacing the DIN connector, I guess this task is on hold until I get and build the CRO.