Message: 2 Date: Wed, 11 Jul 2018 07:54:33 -0500 From: "Don@True-Cal" <t..> To: "'Discussion of precise time and frequency measurement'" <time-nuts@lists.febo.com> Subject: Re: [time-nuts] WTS: Efratom PTB-100 Precision Timebase Message-ID: <015001d41916$5151d780$f3f58680$@gmail.com> Content-Type: text/plain; charset="us-ascii" Thanks everyone for the insightful comments. I've been inspired by off-list help to get this unit working primarily because of the quality of the internal FRK. If nothing else, it has been a tremendous learning experience and after numerous hours studying the manual and bench testing I find myself knowing far more about optical pumping and Rb absorption lines than I thought I ever wanted to know. I keep you posted if I have a breakthrough. Regards, Don Incidentally it might be worth mentioning this. Sulfur is a common breakdown of some encapsulants and atmospheric pollution can be a major headache as H2S though in barely detectable quantities can erode the surface mount and other components if they are exposed. Do any of the components on your unit look even slightly tarnished, if so they will fail soon. I've had this problem with Xbox handsets before possibly due to sulfur from handling. Even a set of digital scales failed due to being in a shed next to PCB etching equipment. I also noticed that sometimes a precision resistor will drift due to heat, as mentioned in the repair guides it can affect even parts near a heat source. -Andre