Guys, This may be of some use to those interested in locking the K3 to an external source. The issue of what kind of source to used has been the subject of a number of postings.
Clifton labs did the above comparison. Jack's Rb standard came in at about .0004 Hz relative to a GPS DO at 10MHz. I was wondering how accurate the EBAY purchased LPRO-101 Rubidium oscillator was. (I wanted to use it as a master oscillator for my test equipment and perhaps later the K3.) Comparisons to WWV indicated that in all liklihood it was well within 1 Hz. There was no way to determine if it drifted within that range. Curiosity finally got the best of me. I purchased an EBAY Trimble Thunderbolt GSP Disciplined oscillator. Supposedly, it is more accurate than the Rb secondary standard. Assuming it's truth, the Rb secondary standard was evaluated via the phase drift method using a dual channel scope. Out of the box, the Rb standard came in at 0.0075 Hz (10 MHz) of the GPS-D0. With a little tweaking of the ten turn pot in the LPRO-101, the two are well within 0.001 Hz (nominally 0.0008Hz) at 10MHz. There is a small drift component of 0.0002Hz after 3 hours after lock. Tweaking isn't straight forward. The appears to be a few minute latency period after a tweak. One can't simply stop the phase angle from moving by turning the pot. Doing so results in an over correction a few minutes later. It's difficult to tweak the Rb standard beyond this degree of accuracy. It takes more than 20 minutes to determine a data point. To do better would take some automation and a phase detector running for several days to get sufficient statistics. Next project is building a phase detector..... I'm pleased. The Rb standard has lots of advantages: Price, minutes to locking on, portability and simplicity. The next question: How accurate is the GPS-DO? Anybody got a hydrogen maser handy? Now what to do with the GPS-DO? Remember when decent receiver dials had only 5 KHz markings? 73 de Brian/K3KO ----- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1390 / Virus Database: 1518/3776 - Release Date: 07/20/11 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
