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ALL TECHNICAL INFORMATION AND SOFTWARE ON THIS PAGE IS USED ON YOUR OWN RISK!!!
YOU HAVE BEEN WARNED. LIVE WITH IT...
The cat interface on the FT-757 is a standard Mini-DIN 6 pin (PS2-style) connector with TTL levels.
An RS232 converter like the MAX232 or similar (I use MAX233) can be used to interface a computer.
Adding a simple opto coupler to this to control the PTT also found in this jack and a 78L05 to supply the
power from the 8V or 13.5V RCA jacks makes this a complete cat interface.
People often use darlington opto-couplers but the 4n35 will probably work just fine.
ONE IMPORTANT THING: If you have problems getting data through from the tranciever to the computer you might
have to add a pull-down resistor to the TTL serial output of the cat connector. About 2K will do. Apparently the 757
does not have any external or internal pull-down resistors on this output.
The problem can apparently be found on other Yaesu rigs as well.
I have bodged together a simple control software for the FT-757GXII. It is freeware and source code is available
on request. It was made using Visual Basic 2005 Express and requires .NET 2.0.
Features include:
Mode and frequency setting
Split mode toggle
Clarifier mode toggle
Gen/ham step toggle
Dial lock toggle
VFO A/B selection
Band Up/Down buttons
Memory Up/Down when in Memory Mode
Status polling of all these values and TX status
Switching between VFO and memory mode - Thanks to Robert, N2JTX.
Bugs are included at no extra cost.
Download: Updated EXE 2009-09-07 v1.1.0.0
Download: Installation package v1.0.0.6
Download: Old EXE file v1.0.0.6