Mike Granby wrote:
I find myself holding a 747 transponder control head that I bought on
eBay as a toy for the kids. But, with echos of Spinal Tap's guitarist
in my head, I notice that the selector knobs allow the digits 0 thru 8
to be selected. What gives?

Just curious - but does it look like either of these:
http://www.angelfire.com/il2/aphs/txp2.jpg
http://www.angelfire.com/il2/aphs/txp.jpg

Or is it a LED display?