Remove space from text output

Hi,
I have this small macro which saves results of two columns in excel to a text file - each 5 seconds. It separates the columns with the space- but for some reason it adds the space BEFORE 1st column. I wonder if it can be changed to remove the first SPACE:

Sub TEST()
    Dim c As Range, r As Range
    Dim output As String
    Calculate
    For Each r In Range("A1:B20").Rows
        For Each c In r.Cells
            output = output & " " & c.Value
        Next c
        output = output & vbNewLine
    Next r
    Open "C:\DATA\signals.txt" For Output As #1
    Print #1, output
    Close
End Sub

Thanks a lot!