VK4MWL wrote: ↑
Sun Dec 11, 2022 3:29 am
Can you please post some more details? GPS model and connection. I'm keen to do this mod.
Very long story.
I wanted an extenal GPS module in a weatherproof box. Most of the ones I found online were USB, but the radio needs serial data
I eventually found a Serial RS232 GPS module on AliExpress, so I ordered 2 of them.
When they arrived, I tried connecting them to my PC via a USB to PC converter module, to test the data, but it didnt work.
After a discussion with G4EML, I checked the serial data using a scope and found it was 10V not 5V signal level and also the signal was inverted.
Looked again on AliExpress and found TTL Serial version of the same module , and ordered 2 of those.
As I'm impacient, I decided to break open one of the RS232 serial GPS modules, and see if I could tap into the data at TTL signal levels, and found that the module was not at all waterproof, and I could take the bottom off by undoing 4 screws
Inside the module was GPS module and a RS232 converter chip.
I unsoldered the Tx data wire and connected it directly to the output of the GPS module, after using my scope to find the TTL GPS serial data pin.
The data could now be seen correctly by my PC.
I initially intended to connect wires to the ribbon connector on the main PCB of the MD9600, but I realised that the 3.3V line was constantly powered on, and the GPS would be constantly powered.
So I disconnected and removed the front panel, took the front panel apart, drilled a hole in the back section of the front panel, for the GPS wires
I found the pads on the PCb where the official GPS module is mounted, specifically the +3.3V Gnd and the data.
Then soldered wires to those pads, and ran the wire back out through the hole I drilled.
I refitted the front panel, then ran the GPS wires acorss the main PCB, away from the RF side of the board, and on my MD9600 V5 hardware there is a rubber bung the rear heatsink, which I removed and fitted a small grommit in its place and rang the wires though the grommet.
I refitted the top of the radio and at the moment I'm using a 4 pin inline PCB connector for the GPS connections, but I will switch to a 3 pin inline socket when I get time to replace it
Look for a external GPS module that says its TTL Serial, NOT RS232
I have not received the second batch of gps modules which claim to be TTL so can't post a link until I receive and verify that they work.