[Elecraft] USB/3.5mm Extension?

[Andy Durbin]

"Yes. At the point for the extension, the signals are RS-232, not USB. You should be able to use a much longer cable if need-be."

Isn't it true that the KAT500 USB cable uses RS-232 protocol but TTL signal levels?  TTL may not be as tolerant of length extension as true RS-232.   Certainly no problem with about 10 ft extension though as my KAT500 USB/Serial extension is close to that long when my KAT500 is connected to the PC .

The KAT500 PC interface is a bit unusual as it seems to be designed to use TLL but also accepts true RS-232 levels with no problem.   A true RS-232 receiver may not operate with a single ended TTL input.  RS-232 signals swing positive and negative and are only zero volts when the driver is not powered.  TTL swings between 0 V and 5 V.  RS-232 compliant transmitters are also required to tolerate continuous short circuit without damage.

Elecraft was careful not to describe the KAT500 PC port, or the USB cable, as RS-232.

These details will only be of interest to anyone considering making a device that interfaces directly with KAT500.

73,
Andy, k3wyc