Re: [time-nuts] Rubidium stability
On 07/22/11 11:48 PM, Perry Sandeen wrote: List, Someone asked about surplus rubidium stability. It was me. Here are my results. I had five Lucent Rubidium’s. Three were from RDR in centennial, CO and two were from the Huntsville hamfest. Before measuring stability, I ran them for a week on the bench. Using A Lucent GPS and a HP 5370B counter I found all of mine between 200 to 800 pico-seconds above or below 10 Mhz. Like someone else, I'm not sure what you mean by ps in this context. Dave ___ 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.
[time-nuts] Rubidium stability
List, Someone asked about surplus rubidium stability. Here are my results. I had five Lucent Rubidium’s. Three were from RDR in centennial, CO and two were from the Huntsville hamfest. Before measuring stability, I ran them for a week on the bench. Using A Lucent GPS and a HP 5370B counter I found all of mine between 200 to 800 pico-seconds above or below 10 Mhz. BTW one can still get the Lucent units (Rubidium and GPS) for $79 and shipping from RDR. I’m not knocking any other supplier but I feel that the Lucent units have more space for hacking so one could discipline the rubidium first and then apply it to the crystal Osc for better phase noise if needed. One pays their money and makes their choices. Regards, Perrier ___ 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.
Re: [time-nuts] Rubidium stability
Perrier: Can you clarify your results? What do you mean by 200 to 800ps above or below 10MHz? Is that how much they gained or lost in a one second period (meaning 2 to 8E-10 error)? Or was it error in period measurement (hopefully not, 8E-3 error). Jose -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Perry Sandeen Sent: Friday, July 22, 2011 3:49 PM To: time-nuts@febo.com Subject: [time-nuts] Rubidium stability List, Someone asked about surplus rubidium stability. Here are my results. I had five Lucent Rubidium’s. Three were from RDR in centennial, CO and two were from the Huntsville hamfest. Before measuring stability, I ran them for a week on the bench. Using A Lucent GPS and a HP 5370B counter I found all of mine between 200 to 800 pico-seconds above or below 10 Mhz. BTW one can still get the Lucent units (Rubidium and GPS) for $79 and shipping from RDR. I’m not knocking any other supplier but I feel that the Lucent units have more space for hacking so one could discipline the rubidium first and then apply it to the crystal Osc for better phase noise if needed. One pays their money and makes their choices. Regards, Perrier ___ 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. ___ 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.
[time-nuts] Rubidium stability
Hi Group, I'm a newbiew and just bought a Lucent RFG-RB rubidium source on Ebay from a reliable seller. I am observing a daily variability of about 80Hz and hourly variability of a few Hz with a calibrated HP 5334B counter (with oven oscillator option). The counter and rubidium source have been powered on for over a week in my basement workgroup which has a stable ambient temperature. I'm using a cannnibalized power supply from an HP-5328A (all the caps replaced) for the 24v rubidium power source ... its supposed to be a quite stable PSU. Is this variability more likely due to the rubidium source (failing bulb) or due to problems with the 5334B counter? Any advice appreciated. Jerry K1JOS ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Rubidium stability
Jerry, 80 Hz is much more than either device should exhibit. There is something seriously wrong, and if you have a short wave receiver that can receive WWV at 10 MHz (AM is fine), you should try to listen to the beat frequency between WWV and either oscillator. That will tell you which is off. You may have to use a small piece of wire plugged into the BNC of either oscillator as an antenna. adjust the length and/or separation with your receiver to adjust the level so that you hear a beat frequency with WWV. Alternately, try to borrow a known good counter from someone local. In either case, an oscilloscope would help check the outputs. When an oscillator is way off in frequency, the signal may not look right on the scope. Didier JOS Earthlink wrote: Hi Group, I'm a newbiew and just bought a Lucent RFG-RB rubidium source on Ebay from a reliable seller. I am observing a daily variability of about 80Hz and hourly variability of a few Hz with a calibrated HP 5334B counter (with oven oscillator option). The counter and rubidium source have been powered on for over a week in my basement workgroup which has a stable ambient temperature. I'm using a cannnibalized power supply from an HP-5328A (all the caps replaced) for the 24v rubidium power source ... its supposed to be a quite stable PSU. Is this variability more likely due to the rubidium source (failing bulb) or due to problems with the 5334B counter? Any advice appreciated. Jerry K1JOS ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Rubidium stability
Jerry, Is this variability more likely due to the rubidium source (failing bulb) or due to problems with the 5334B counter? Obviously you need a third source for comparison while locking your counter to the Rb source. I gather from the web that the Lucent unit uses an Efratom module in which case there should be a lamp voltage display or at least a measurement pin for it available somewhere. I posted an old Efratom FRK manual to BAMA some time ago which may give you a clue. A good lamp will show better than 5V although this is actually the voltage on the output of the photo-detector amp. New lamps are available on the web although I replaced mine in a Racal 9475 Rb standard some time ago with no obvious improvement; it still reads 5.8V when the manual says it should be between 6 and 12V. I was told once that varnish can slowly evaporate onto the cell window thus reducing optical transparency. Don't know if this is true but it is a thought. Cheers - Joe G3LLV ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Rubidium stability
Jerry, Do you have a heat sink mounted to the Rb source ? It sounds, possibly, like a heater not reaching equilibrium. Didier's suggestion of comparing against WWV would be a good start to find who is at fault. Your counter time base may have an unknown problem. BillWB6BNQ Didier Juges wrote: Jerry, 80 Hz is much more than either device should exhibit. There is something seriously wrong, and if you have a short wave receiver that can receive WWV at 10 MHz (AM is fine), you should try to listen to the beat frequency between WWV and either oscillator. That will tell you which is off. You may have to use a small piece of wire plugged into the BNC of either oscillator as an antenna. adjust the length and/or separation with your receiver to adjust the level so that you hear a beat frequency with WWV. Alternately, try to borrow a known good counter from someone local. In either case, an oscilloscope would help check the outputs. When an oscillator is way off in frequency, the signal may not look right on the scope. Didier JOS Earthlink wrote: Hi Group, I'm a newbiew and just bought a Lucent RFG-RB rubidium source on Ebay from a reliable seller. I am observing a daily variability of about 80Hz and hourly variability of a few Hz with a calibrated HP 5334B counter (with oven oscillator option). The counter and rubidium source have been powered on for over a week in my basement workgroup which has a stable ambient temperature. I'm using a cannnibalized power supply from an HP-5328A (all the caps replaced) for the 24v rubidium power source ... its supposed to be a quite stable PSU. Is this variability more likely due to the rubidium source (failing bulb) or due to problems with the 5334B counter? Any advice appreciated. Jerry K1JOS ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
