# Port

Connect your K3 via a 9-pin straight-through serial (RS-232) cable to your computer.

If your computer does not have an available serial port, you may use a USB to Serial Adapter such as the Elecraft KUSB.

### Serial Port

Choose the Computer's serial port that is connected to the K3. Click the arrow to open a list of available ports, then select the port you have connected to the K3. See Finding the appropriate serial port for a USB to Serial Adapter if you're using a USB to Serial Adapter and are not sure which port to choose.

### Refresh Port List

Click to update the list of available serial ports, which may be helpful if you plug in a USB to Serial Adapter after the program has started.

### Test Communications

Verifies that the K3 Utility can communicate with your K3 and determine its RS-232 speed.

If you change the K3's RS-232 speed using the K3 front panel CONFIG:RS-232 menu selection or by entering a K3 command in the Command Tester, use this button to allow the K3 Utility to discover the K3's new speed.

Note: If the K3 is already loaded with MCU firmware (as indicated by a VFO frequency in the K3's LCD display), it should respond to Test Communications with an "Information" dialog indicating that the K3 is running the "Main" program. The speed shown should match the K3 CONFIG:RS-232 menu selection.

If the K3 is in a "Boot Loader" state, as indicated by the letters "MCU LD" on the LCD display, the K3 should respond to Test Communications with a "Warning" dialog that looks like this:

If the K3 has a running MCU (as indicated by a valid VFO A display) and Test Communications results in this Warning dialog, the K3 Utility is not communicating with the K3.

A K3 in its boot loader, modems, null modem cables, and defective serial cables can echo whatever is sent to them. The K3 Utility cannot tell what device is attached without sending a block of firmware. If MCU firmware load fails on the first block (address x0800), it is very likely that the communications cable is not correctly attached to your K3, the cable is defective, or the wrong serial port has been chosen.