Thinking of building another signal tracer. Something no shack should be with out. I lost mine a few years ago when a flood hit the shack. The one I had was built by another ham and was tube type. So looking to build this one in the next day or so: http://www.qsl.net/iz7ath/web/02_brew/15_lab/01_tracer/pag01_eng.htm I would love to build one with a tube but have not looked many designs.