ok thanks bob i will give it a go ian ----- Original Message ----- From: "Robert D. Mantell" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Saturday, December 06, 2003 11:23 AM Subject: Re: [Repeater-Builder] Re: crystal alignment (how accurate is accurate)
> It never fails - pose a simple question, and you get a series of overly > complicated answers involving > expensive equipment. To calibrate a local frequency standard, one needs > a short wave rx with an > s meter (mechanical type), and a means of balancing the local standard > signal level with that of WWV > at 10 MHz. All you need to do is adjust the local standard while > watching the s meter. As it is > adjusted, you will notice the s meter flutter at a decreasing rate as > you reach 10 Mhz. When you > are dead on, the s meter will drift slower and finally stop. You are > there. And please, do not argue > about doppler, selective fading, etc. Sure you will be able to see > these effects, but they will not affect > the accuracy of this operation. Just watch for the response when the > WWV or whatever signal is steady. > > I hope this helps > > Bob - W3TGG > > [EMAIL PROTECTED] wrote: > > >Ian, you should have time standard frequencies in Australia on 5 10 and 15 > >MHz. If you have a secondary receiver, tune in the 10 MHz and compare it to the > >output of the 10 MHz timebase in your service monitor. > > > >This has been one of my obsessions for a while now, to find a way of more > >accurately setting my 10 MHz timebase in my service monitor. > > > >Zero beating with our WWV signal will only get you within a cycle or so. > >(i.e., one cycle off at 10 MHz equals 40 hertz error at 400 MHz) And then there's > >trying to find a time when the signal is strong and doesn't fade too much. > >Since I live about 50 miles south of Ft Collins you would think I would have a > >strong signal all the time, but no. > > > >So I figure there must be a way to use a scope to compare two audio signals > >(X/Y like we do with PL tones) and be able to set it more accurately. I have > >tried comparing the 1000 cycle audio tone from an external receiver when I > >generate a signal from the service monitor I kc off frequency from WWV. Then > >comparing that to the 1kc tone generated from the monitors own PL tone generator > >(phase locked to the 10 MHz time bases). You should be able to see a slow drift > >between the two on the oscilloscope but so far no success, too much noise to > >see much. > > > >Does someone have a way of getting closer than 1 cycle? (no I haven't bought > >a GPS timebase receiver yet but have drooled over them on Ebay. > > > >I've always wondered if a tuned RF receiver using 10 MHz crystals for IF > >filters would give you a strong 10 MHz carrier that could be used for calibration. > > > >Hopefully this is still somewhat on topic since we all need to set our > >repeaters on frequency. > > > >Art - KC7GF > >Golden, CO > > > > > > > > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
