On my 6700 I cannot get the GPSDO to work.The factory just installed the optional GPSDO.I tried the supplied antenna, waited an hour, no luck. I tried a Tram Model 1655 no luck. My Sat look angle outside looks good.I looked for + 3 DC volts on the antenna line and their was none. I tried rebooting the software & hardware several times no luck. I tried clicking the GPS software Install and uninstall several times as suggested and rebooting... no luck. I checked the Internal GPS antenna and 10 MHz cables and they don't show shorted and do show continuity. I opened the GPSDO cover and I do see +3Volts on a couple test points on the GPSDO board?? Other than that the radio works fine. I am on version 184.108.40.206 Any suggestions you have would be greatly appreciated. Thank you, Jerry Dixon KC0KW.