{"id":128,"date":"2023-01-24T14:29:58","date_gmt":"2023-01-24T13:29:58","guid":{"rendered":"http:\/\/sp5tof.vxm.pl\/?page_id=128"},"modified":"2025-11-21T18:53:32","modified_gmt":"2025-11-21T17:53:32","slug":"yaesu-757-gx2-external-display","status":"publish","type":"post","link":"https:\/\/sp5tof.pl\/?p=128","title":{"rendered":"Yaesu 757 GX2 external display"},"content":{"rendered":"

I have started this project in 2015. \u00a0Finally, after some modifications, I decided to publish it.<\/p>\n

Yaesu 757GX2 is a quite old transceiver. Any repleacements parts are out of stock, no longer manufactured.
\n\"\"<\/p>\n

I have purchased the transceiver with broken VFD display and decided to build the display on my own. It wasn’t simple job to do. In the very beginning, I made a decision of fit\u00a0the LED segment display in\u00a0the trx instead of broken one. Although, I gave up\u00a0with this idea.<\/p>\n

I found some solutions for similar problem in the net, but\u00a0\u00a0neither of them seems to solve my problem: broken VFD, but the processor (TMS2370) was fine.<\/p>\n

Based on 757’s\u00a0\u00a0user manual, espacially the CAT description interface, I decided to build the interface based on my favourite programmable platform – Arduino, to read the TRX status and\u00a0show it on the external display.
\n\"\"<\/p>\n

Before I’ve \u00a0started my fight with 757GX2 CAT interface, I found the James’es (VE3BUX) site with the library of FT-857D dedicated for Arduino to use with CAT interface. Unfortunatelly, this radio has a completely different protocol structure. What is more the software serial library had to be modified additionaly.<\/p>\n

I used 4×20 LCD display. The connector used for CAT interface in 757GX2 is a mini-DIN 6PIN. Be careful, becouse I purchased two types of 6PIN mini-DIN \u00a0! The difference based on the connector’s shape. The 6PIN mini DIN purchased at TME (this one<\/a>) doesn’t fit. The 6PIN mini-DIN SVHS did the job (this one<\/a>). This is the same connector like the PS\/2 keyboard. The power supply(8 or 12V) is taken by RCA connector from TRX.<\/p>\n

\"\"<\/p>\n

CAT socket.\u00a0<\/strong><\/p>\n

S.OUT -> RX_YAESU, S.IN -> TX_YAESU<\/strong><\/p>\n

In the very beginning I was struggling with operate at high power. The LCD display have been showing mess when I had increased power to 50W-100W. I was fighting with it for many weeks and finally found a solution. I used the inductance and tantal capacitor within the power line of uC fo filter undemanded intereferences.<\/p>\n

The whole device is opto-isolated from TRX by using the optocouplers on TX and RX line. The 757GX2 CAT interface is used \u00a0a TTL logic level .<\/p>\n

\"\"<\/p>\n

Please see this device in action:<\/p>\n