Hi Brian, Interesting post. I've read of others using GPS this way, but what does this kind of accuracy buy you when maybe 1 in 100,000 other hams go to this kind of trouble?
73, Ken Alexander VE3HLS --- On Wed, 7/20/11, Brian Alsop <[email protected]> wrote: > From: Brian Alsop <[email protected]> > Subject: [Elecraft] Rb & GPS DO comparison > To: [email protected] > Date: Wednesday, July 20, 2011, 2:41 PM > 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 > ______________________________________________________________ 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
