I would like this code to validate the data for all of column F - any
suggestions?

Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo OuttaHere
If Target.Address = "$F$4" Then '<<<< change cell
Application.EnableEvents = False
Dim strText As String
Dim lngN As Long
Const str_Chars As String = "[0-9a-zA-Z ]"
strText = Target.Text

For lngN = 1 To Len(strText)
If Not Mid$(strText, lngN, 1) Like str_Chars Then
MsgBox "Only numbers or alphabetic characters allowed. ", _
vbOKOnly, "Data Validation"
Application.Undo
Exit For
End If
Next 'lngN
End If
OuttaHe
Application.EnableEvents = True
End Sub