Besides having higher voltages, a USB to RS232 signal will be inverted compared with a RS232 TTL signal.

On Tuesday, August 29, 2023 at 10:29:30 AM CDT, Jerry Moyer via groups.io <ac5jm@...> wrote:

Just curious if anyone has seen this and might know what's going on.? Using Putty on the CAT port of a QCX-Mini, the QCX returns a (`) with each character typed.? ?For example, if I type FA; and then ENTER, it returns a ` with each character typed.? I have Putty set to 38400 8,N,1.? I can't remember what flow control was set to but it appears from the manual that it doesn't matter.? The USB to RS232 cable that I'm using outputs 6 volts (unloaded) which I assumed is close enough to TTL level so as not to harm the unit. (did I assume correctly?)? I reversed the tip and ring just to make sure I had it connected correctly and no characters are returned.? I also connected tip and ring together for a loop-back test and characters that I type are returned on the screen on Putty.??

This followed a catastrophic accident just as I finished construction where I dropped a metallic object onto the top of the unit on the pins that connect the LCD to the Micro-Processor.? I replaced the Micro-processor with a new one from QRP Labs.? The LCD only shows only blank (black) characters after the accident.? I have a replacement display on order.? According to the manual, the LCD shares 2 of those pins with the CAT port.

I have verified that VFO tuning works by following the signal on a spectrum analyzer as I tune the frequency by wrapping a wire around the unit to use as an antenna for the spectrum analyzer.??

Thanks,

Jerry AC5JM

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