Hi Brian, If you want to go straight to the top of the frequency measuring heap, I have a GPS-disciplined Rubidium for sale ;-) It's a NIB Symmetricom StarLoc II Plus, that gives you GPS accuracy when it's locked to the sats, and Rubidium accuracy when it's in holdover.
I've been a ham long enough to remember when I was happy to know that I was inside the band! 73, geo - n4ua On Wed, Jul 20, 2011 at 2:52 PM, Ken Alexander <[email protected]>wrote: > 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 > ______________________________________________________________ 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
