Hi Jerry, SIW uses a double-ovenized OCXO source to drive a DDS and put the frequency at 185.2993 kHz. It should stay quite close to that (until something fails, of course!). And to Dex, thanks for the report from NC. NDBs in that direction are coming in here well tonight so it's not surprising SIW is making it down your way too. 73, Garry, K3SIW, EN52ta, Elgin, IL