Sure, you can use a custom Validate script for the text field that looks like:
// Custom Validate script
getField("checkbox1").value = event.value ? "Yes" : "Off";
Replace "Yes" with the actual export value of the check box (which defaults to "Yes") and "checkbox1" with the actual name of the corresponding check box.
Do you want to do this when any text is filled-in the field, or just when some specific text is entered into it?
Thanks for the relay, any text. The above post solved my issue
Thanks for your help. It worked
A better code, one that is not dependent on the export value of the check-box, is: