hi again bob i carnt receive any signal on 10 meg . thansk ian ----- Original Message ----- From: "ian wells" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Saturday, December 06, 2003 3:33 PM Subject: Re: [Repeater-Builder] Re: crystal alignment (how accurate is accurate)
> ok thanks bob i will give it a go > ian > ----- Original Message ----- > From: "Robert D. Mantell" <[EMAIL PROTECTED]> > To: <[email protected]> > 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/ > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
