> The GPSDO I want to use has an output rich in harmonics. In some> cases that is good, but Murphy rules and in the application I have> today, it is not good.> > I need a 10 MHz Band-Pass Filter, Bandwidth is not critical, something> small with SMA connectors would be ideal, but I can live with BNC.> > Anyone have such a beast or know where I can get one ? I checked Mini-Circuits> and choked on the price !!> > Thanks, Dick, W1KSZ> Hi Dick, There are plans for a simple nine section low pass filter here: http://jwmeng.com/AppNote/AppNote003.html You can also use (I did) a filter from an old 10mbit ethernet network card, as suggested here: http://www.uhf-satcom.com/misc/10MHz_dist/ I joined this list just yesterday, so hello to everyone. I live in Madrid and I'm interested in frequency measurement for HAM purposes. Not understanding most of the things you guys discuss here, I thought I would never have the opportunity to give my 2 cents... I´m currently working on a simple GPSDO that (luckily) some of you may find interesting. I'll send you details in a few days so I can get your opinions and (hopefully) it inspires/helps someone. Bests Regards & 73's Roberto Barrios, EB4EQA Madrid, Spain _________________________________________________________________ See how Windows® connects the people, information, and fun that are part of your life http://clk.atdmt.com/MRT/go/119463819/direct/01/

Roberto Barrios wrote: >> The GPSDO I want to use has an output rich in harmonics. In some> cases that is good, but Murphy rules and in the application I have> today, it is not good.> > I need a 10 MHz Band-Pass Filter, Bandwidth is not critical, something> small with SMA connectors would be ideal, but I can live with BNC.> > Anyone have such a beast or know where I can get one ? I checked Mini-Circuits> and choked on the price !!> > Thanks, Dick, W1KSZ> >> > Hi Dick, > > There are plans for a simple nine section low pass filter here: > http://jwmeng.com/AppNote/AppNote003.html > > You can also use (I did) a filter from an old 10mbit ethernet network card, as suggested here: > http://www.uhf-satcom.com/misc/10MHz_dist/ > > I joined this list just yesterday, so hello to everyone. I live in Madrid and I'm interested in frequency measurement for HAM purposes. Not understanding most of the things you guys discuss here, I thought I would never have the opportunity to give my 2 cents... I´m currently working on a simple GPSDO that (luckily) some of you may find interesting. I'll send you details in a few days so I can get your opinions and (hopefully) it inspires/helps someone. > > Bests Regards & 73's > Roberto Barrios, EB4EQA > Madrid, Spain > > > Roberto But what is the filter phase shift tempco? In the presence of temperature changes the filter phase shift variation is equivalent to phase and frequency modulation of the output of the filter. One cure is to use low tempco filter parts and place the filter in an oven. Bruce

Hi Roberto, Congratulations! On your very first visit here, you have hit the Bruce Effect. Do not be alarmed! Just place your filter in a temperature controlled oven regulated to a change of 1E-99C for external temp changes of -100C to +200C and you may be alright, I did say "may". But then, for ham purposes, the phase/frequency changes should make no difference to you. If you were NIST, well that would be another matter. But this is a time-nuts forum and people here think in the 1E-16 range. Some of us here just strive for the best and find that some of our needs are easily covered with much more modest equipment. That does not mean we are happy to accept this limited capability for projects we may wish to do in the future. You have made a wise choice coming here, it has low noise (accept for my posts) and some of the best minds contributing. Keep watching this space and join in to ask question and give ideas. Do not be put off by any comments on what you post, there are high ideals here and some may not be the most tactful people when they make their comments. You will learn a great deal here and you will certainly get the time bug. 73, Steve - ZL3TUV & G8KVD 2009/1/9 Bruce Griffiths <bruce.griffiths@xtra.co.nz>: > Roberto Barrios wrote: >>> The GPSDO I want to use has an output rich in harmonics. In some> cases that is good, but Murphy rules and in the application I have> today, it is not good.> > I need a 10 MHz Band-Pass Filter, Bandwidth is not critical, something> small with SMA connectors would be ideal, but I can live with BNC.> > Anyone have such a beast or know where I can get one ? I checked Mini-Circuits> and choked on the price !!> > Thanks, Dick, W1KSZ> >>> >> Hi Dick, >> >> There are plans for a simple nine section low pass filter here: >> http://jwmeng.com/AppNote/AppNote003.html >> >> You can also use (I did) a filter from an old 10mbit ethernet network card, as suggested here: >> http://www.uhf-satcom.com/misc/10MHz_dist/ >> >> I joined this list just yesterday, so hello to everyone. I live in Madrid and I'm interested in frequency measurement for HAM purposes. Not understanding most of the things you guys discuss here, I thought I would never have the opportunity to give my 2 cents... I´m currently working on a simple GPSDO that (luckily) some of you may find interesting. I'll send you details in a few days so I can get your opinions and (hopefully) it inspires/helps someone. >> >> Bests Regards & 73's >> Roberto Barrios, EB4EQA >> Madrid, Spain >> >> >> > Roberto > > But what is the filter phase shift tempco? > In the presence of temperature changes the filter phase shift variation > is equivalent to phase and frequency modulation of the output of the filter. > One cure is to use low tempco filter parts and place the filter in an oven. > > Bruce > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW Omnium finis imminet