[aprssig] has anyone built/modified a USB to TTL level converter??

[Greg D]

Hi Bob,

Uh, let me see if I have this right...

You are trying to drive your IC706 rig from a computer. The computer has 
a regular (RS-232) serial port (or you can make one with a standard 
dongle), and the radio needs TTL. You want to connect the two, right?

A TTL "high" signal (+3v or so) translates to a negative half dozen 
volts or so on RS-232, and a TTL "low" (0v) maps to a positive half 
dozen volts or so on RS-232. You don't need to make this any more 
complicated than it is.

If you're halfway handy with a soldering iron, to drive the rig from the 
computer, all you need is a transistor, diode, and a resistor or two. 
Let me know if you are interested and I can dig up the schematic. I 
drive my Yaesu FT-736R like this, and it works great.

To drive the computer from the rig, it's something equally simple. The 
Yaesu rig doesn't talk back to the computer (really annoying!), but I 
think the diagram I'm remembering has both directions covered. If you 
can find the schematic for the original FODTrack satellite tracking 
controller, I believe it's in there.

Greg KO6TH


Bob wrote:
> I need TTL.
> I have RS232
> I have USB
> I do not have a RS232 port. Rules out the standard USB to RS232 dongle.
>
> I think that I want to take an old cell phone to computer interface that has
> a USB to RS232 level converter. It is a common chip, and I have the drivers.
>
> I want to take the RS232 from the cell phone cable and feed it to a MAX233
> to get TTL in/out.
>
> Then use the TTL to talk to the IC706m2g to control the radio.
>
> Without reinventing the wheel, is there a "better way"?
>
> Bob K8YS
>
>
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