Hi all, Many thanks to everyone who responded so far. I am taking notes and will be trying all of the ideas as soon as possible. I'll report results to the group.
Jim Robbins, N1JR -----Original Message----- >From: [EMAIL PROTECTED] >Sent: Jun 6, 2008 11:41 PM >To: [email protected] >Subject: time-nuts Digest, Vol 47, Issue 16 > >Send time-nuts mailing list submissions to > [email protected] > >To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >or, via email, send a message with subject or body 'help' to > [EMAIL PROTECTED] > >You can reach the person managing the list at > [EMAIL PROTECTED] > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of time-nuts digest..." > > >Today's Topics: > > 1. Re: Measuring Rubidium frequencies (Magnus Danielson) > 2. Re: Measuring Rubidium frequencies (David C. Partridge) > 3. Re: Measuring Rubidium frequencies (Adrian) > 4. Re: Measuring Rubidium frequencies (David C. Partridge) > 5. Re: Measuring Rubidium frequencies (Bill Hawkins) > 6. Re: Measuring Rubidium frequencies (David C. Partridge) > 7. pcb question ([EMAIL PROTECTED]) > > >---------------------------------------------------------------------- > >Message: 1 >Date: Fri, 06 Jun 2008 18:30:16 +0200 (CEST) >From: Magnus Danielson <[EMAIL PROTECTED]> >Subject: Re: [time-nuts] Measuring Rubidium frequencies >To: [email protected], [EMAIL PROTECTED] >Message-ID: <[EMAIL PROTECTED]> >Content-Type: Text/Plain; charset=us-ascii > >From: "Jim Robbins" <[EMAIL PROTECTED]> >Subject: [time-nuts] Measuring Rubidium frequencies >Date: Fri, 6 Jun 2008 09:01:48 -0400 >Message-ID: <[EMAIL PROTECTED]> > >Jim, > >> I have a problem which I am unable to understand and need some help. I have >> two M100 Rubidiums, a Racal 1992 counter, a factory standard T'Bolt and a >> Symmetricom Starloc II. When I set up either GPSDO as the External Timebase >> for the 1992 and measure either Rubidium, I get the same reading of >> 9.99998278. When I use the 1992's Internal Timebase, I get 9.99999995. All >> equipment has warmed up. The antenna is a Symmetricom HP 58532A on the >> roof. On a few occasions I have seen the frequency drift up to >> 0.00001722. I would have expected that both Rubies would have read >> 0.00000000. Any ideas would be much appreciated. > >Do you have propper levels at the reference input? >If you have a too weak signal you may miss a cycle every now and then. > >The same can happend if your measurement input has the trigger point in the >wrong spot. However, I suspect the reference input is much sparser in design >than the measurement input. This put more requirements on the signal and >"should not be a problem". > >This would however make your counter show larger numbers. > >The best thing you can do is to take a RF generator, dial it to 10 MHz and >dial the amplitude to different levels while feeding the reference input. >Watch for the same kind of anomalies. > >Another thing which may kill you is interference. Additive interference can add >additional cycles. Now, for a frequency counter and its reference input >it produces the interesting feature of showing lower numbers than it should, >since your actual reference runs at a higher frequency than you think. > >So, given that it is the external references which produces lower numbers, I'd >bet that you have additive interference on the 10 MHz signal. I'd suspect a >lower frequency than 10 MHz. Putting an RF-choke on the cable may help. >If you have a spectrum analyzer at hand, use that, but for the signal to have >impact it needs to be fairly strong, so scoping it may do the trick. However, >you must scope it with the counter connected to recreate the same environment. > >It may very well be a switching supply that upsets you. One trick would be to >isolate the parts so that they are not part of a larger interfering >environment. Another trick is to just turn off everything not needed for the >measurement. Regardless, it seems like additive interference. > >One counter-action you can take is to convert your 10 MHz to a squarewave. >The slewrate of the square leaves less time for the interference to interact >with the signal. RF chokes in addition may help. > >Cheers, >Magnus > > > >------------------------------ > >Message: 2 >Date: Fri, 6 Jun 2008 17:45:23 +0100 >From: "David C. Partridge" <[EMAIL PROTECTED]> >Subject: Re: [time-nuts] Measuring Rubidium frequencies >To: "'Discussion of precise time and frequency measurement'" > <[email protected]> >Message-ID: <[EMAIL PROTECTED]> >Content-Type: text/plain; charset="US-ASCII" > >Curious also that 9.99998278 +.00001722 = 10.000000000 > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >Behalf Of Jim Robbins >Sent: 06 June 2008 14:02 >To: [email protected] >Subject: [time-nuts] Measuring Rubidium frequencies > >Hi all, > >I have a problem which I am unable to understand and need some help. I have >two M100 Rubidiums, a Racal 1992 counter, a factory standard T'Bolt and a >Symmetricom Starloc II. When I set up either GPSDO as the External Timebase >for the 1992 and measure either Rubidium, I get the same reading of >9.99998278. When I use the 1992's Internal Timebase, I get 9.99999995. All >equipment has warmed up. The antenna is a Symmetricom HP 58532A on the >roof. On a few occasions I have seen the frequency drift up to >0.00001722. I would have expected that both Rubies would have read >0.00000000. Any ideas would be much appreciated. > >many thanks, >Jim Robbins >_______________________________________________ >time-nuts mailing list -- [email protected] To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > > > > >------------------------------ > >Message: 3 >Date: Fri, 06 Jun 2008 19:10:18 +0200 >From: Adrian <[EMAIL PROTECTED]> >Subject: Re: [time-nuts] Measuring Rubidium frequencies >To: Discussion of precise time and frequency measurement > <[email protected]> >Message-ID: <[EMAIL PROTECTED]> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed > >Jim, > >it might be much easier than you're thinking... > >Are you sure the GPDSO's are locked? >Are you sure the rubidium oscillators are locked? >What is the reading of your GPDSO's when you measure them with the >internal counter time base? > >I would say that neither 0.00001722 nor 0.00000000 can be correct for a >10.000,000 MHz signal. >Something with your figures appears to be dead wrong, IMO. > >Adrian > > >Jim Robbins schrieb: >> Hi all, >> >> I have a problem which I am unable to understand and need some help. I have >> two M100 Rubidiums, a Racal 1992 counter, a factory standard T'Bolt and a >> Symmetricom Starloc II. When I set up either GPSDO as the External Timebase >> for the 1992 and measure either Rubidium, I get the same reading of >> 9.99998278. When I use the 1992's Internal Timebase, I get 9.99999995. All >> equipment has warmed up. The antenna is a Symmetricom HP 58532A on the >> roof. On a few occasions I have seen the frequency drift up to >> 0.00001722. I would have expected that both Rubies would have read >> 0.00000000. Any ideas would be much appreciated. >> >> many thanks, >> Jim Robbins >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > > > >------------------------------ > >Message: 4 >Date: Fri, 6 Jun 2008 20:41:07 +0100 >From: "David C. Partridge" <[EMAIL PROTECTED]> >Subject: Re: [time-nuts] Measuring Rubidium frequencies >To: "'Discussion of precise time and frequency measurement'" > <[email protected]> >Message-ID: <[EMAIL PROTECTED]> >Content-Type: text/plain; charset="US-ASCII" > >The 1992 doesn't display the leading 1 when its in when in maximum accuracy >mode. So for 0.0000 read 10.0000 and of course apply the 10**6 multiplier. > >Dave > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >Behalf Of Adrian >Sent: 06 June 2008 18:10 >To: Discussion of precise time and frequency measurement >Subject: Re: [time-nuts] Measuring Rubidium frequencies > >Jim, > >it might be much easier than you're thinking... > >Are you sure the GPDSO's are locked? >Are you sure the rubidium oscillators are locked? >What is the reading of your GPDSO's when you measure them with the internal >counter time base? > >I would say that neither 0.00001722 nor 0.00000000 can be correct for a >10.000,000 MHz signal. >Something with your figures appears to be dead wrong, IMO. > >Adrian > > >Jim Robbins schrieb: >> Hi all, >> >> I have a problem which I am unable to understand and need some help. I >have two M100 Rubidiums, a Racal 1992 counter, a factory standard T'Bolt and >a Symmetricom Starloc II. When I set up either GPSDO as the External >Timebase for the 1992 and measure either Rubidium, I get the same reading of >9.99998278. When I use the 1992's Internal Timebase, I get 9.99999995. All >equipment has warmed up. The antenna is a Symmetricom HP 58532A on the >roof. On a few occasions I have seen the frequency drift up to >0.00001722. I would have expected that both Rubies would have read >0.00000000. Any ideas would be much appreciated. >> >> many thanks, >> Jim Robbins >> _______________________________________________ >> time-nuts mailing list -- [email protected] To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > >_______________________________________________ >time-nuts mailing list -- [email protected] To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > > > > >------------------------------ > >Message: 5 >Date: Fri, 6 Jun 2008 14:44:26 -0500 >From: "Bill Hawkins" <[EMAIL PROTECTED]> >Subject: Re: [time-nuts] Measuring Rubidium frequencies >To: "'Discussion of precise time and frequency measurement'" > <[email protected]> >Message-ID: <[EMAIL PROTECTED]> >Content-Type: text/plain; charset="us-ascii" > >It might be even easier than that. > >As a long-time user of the 1992, I know I'll get weird results >if I fail to turn on the 50 ohm terminator for the input(s). > >Your 1992 will also do phase A-B measurements. This is a great >way to compare standards if you don't have the expensive stuff. >Don't know about the terminator for the external standard since >I don't use it, using phase instead. > >Bill Hawkins > > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >Behalf Of Adrian >Sent: Friday, June 06, 2008 12:10 PM >To: Discussion of precise time and frequency measurement >Subject: Re: [time-nuts] Measuring Rubidium frequencies > >Jim, > >it might be much easier than you're thinking... > >Are you sure the GPDSO's are locked? >Are you sure the rubidium oscillators are locked? >What is the reading of your GPDSO's when you measure them with the >internal counter time base? > >I would say that neither 0.00001722 nor 0.00000000 can be correct for a >10.000,000 MHz signal. >Something with your figures appears to be dead wrong, IMO. > >Adrian > > >Jim Robbins schrieb: >> Hi all, >> >> I have a problem which I am unable to understand and need some help. >I have two M100 Rubidiums, a Racal 1992 counter, a factory standard >T'Bolt and a Symmetricom Starloc II. When I set up either GPSDO as the >External Timebase for the 1992 and measure either Rubidium, I get the >same reading of 9.99998278. When I use the 1992's Internal Timebase, I >get 9.99999995. All equipment has warmed up. The antenna is a >Symmetricom HP 58532A on the roof. On a few occasions I have seen >the frequency drift up to 0.00001722. I would have expected that both >Rubies would have read 0.00000000. Any ideas would be much appreciated. >> >> many thanks, >> Jim Robbins > > > > > >------------------------------ > >Message: 6 >Date: Fri, 6 Jun 2008 21:34:05 +0100 >From: "David C. Partridge" <[EMAIL PROTECTED]> >Subject: Re: [time-nuts] Measuring Rubidium frequencies >To: "'Discussion of precise time and frequency measurement'" > <[email protected]> >Message-ID: <[EMAIL PROTECTED]> >Content-Type: text/plain; charset="US-ASCII" > >>As a long-time user of the 1992, I know I'll get weird results if I fail to >turn on the 50 ohm terminator for the input(s). > >Oh yes indeed! > >Dave > > > > >------------------------------ > >Message: 7 >Date: Fri, 6 Jun 2008 23:41:20 EDT >From: [EMAIL PROTECTED] >Subject: [time-nuts] pcb question >To: [EMAIL PROTECTED], [email protected] >Message-ID: <[EMAIL PROTECTED]> >Content-Type: text/plain; charset="us-ascii" > >Hello Norm, > >yes, you are right, that's the way I do it. You can see that on the two >attached pics. You can also see that I sometimes cut small islands into the >Copper with an Exacto knife to solder down through hole parts and Tantalum >caps >for example. > >For SMD IC's I solder down the GND pins, then use small caps from the board >to the power pins, and wire the VCC with rework wire. > >Excuse the poor picture/board quality, these are the only two boards I had >able to be photographed - I usually use thermal glue to seal the finished >boards. > >This is a very quick and dirty, and surprisingly good electrical way to >build something. I've done circuits with over 1GHz like this! > >Hope that helps, >bye, >Said > > >In a message dated 6/6/2008 15:50:40 Pacific Daylight Time, SAIDJACK writes: > > > >____________________________________ > From: [EMAIL PROTECTED] >To: [EMAIL PROTECTED] >Sent: 6/6/2008 14:15:10 Pacific Daylight Time >Subj: pcb question > > >Said, >I subscribe to the timenuts reflector. A few days ago(June 2), you >described a method of dead bug construction using SMT IC's and discrete >components. Do you have any pics of the details? How exactly do you >attach the bypass caps to the power pins? >My assumption is you're using single sided fr4 and the copper is ground, >with vcc wired as needed. > >This will be my first try at SMT. I've played a bit with wire wrap and >plugboard. > >This will be used for a pulse shaper/divider network. >Thank you for any help! >Norm n3ykf > > > > > > >**************Get trade secrets for amazing burgers. Watch "Cooking with >Tyler Florence" on AOL Food. >(http://food.aol.com/tyler-florence?video=4?&NCID=aolfod00030000000002) >-------------- next part -------------- >A non-text attachment was scrubbed... >Name: SMD.jpg >Type: image/jpeg >Size: 43646 bytes >Desc: not available >Url : >http://www.febo.com/pipermail/time-nuts/attachments/20080606/d5b8e86c/attachment.jpg > >-------------- next part -------------- >A non-text attachment was scrubbed... >Name: smd2.jpg >Type: image/jpeg >Size: 47615 bytes >Desc: not available >Url : >http://www.febo.com/pipermail/time-nuts/attachments/20080606/d5b8e86c/attachment-0001.jpg > > >------------------------------ > >_______________________________________________ >time-nuts mailing list >[email protected] >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >End of time-nuts Digest, Vol 47, Issue 16 >***************************************** _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
