Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
I've posted some General Radio notes and specifications on their Model 1115-B oscillator, hoping there might be some relevance to the Model 1120. Product specific information starts on page 8. http://www.ni6e.com/genrad/ Regards, Peter NI6E Max Robinson wrote: There must have been several different versions of this unit. The oscillator I have is 5 MHz. The frequency dividers in the rack I got it out of were discrete transistor construction. Seems to me the clock used a 25L6 although I don't remember how they derived the heater voltage. There was also a phase locked frequency multiplier with outputs at 10 MHz, 100 MHz and 1 GHz. The frequency divider module had outputs down to 1 PPS. After typing that I'm not sure the oscillator frequency is right. Maybe it's 1 MHz. I'm sure it's not 100 kHz. Regards. Max. K 4 O D S. ___ 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] Restoring GR 1120-AB Frequency Standard
Peter, Thanks for the posting and the link. I believe that the 1115-B was the successor to the GR 1113-A that I am restoring. It combines a number of the features of the 1113-A and 1114-A in the same chassis along with a self-contained 24 emergency power supply. Note that the crystal oven design was completely revamped. No double oven. Lower power requirements. The 1120 was described in the April 1961 issue of GR Experimenter. Best Regards, Russ WA3FRP -Original Message- From: Peter Putnam [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sat, 23 Aug 2008 6:47 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard I've posted some General Radio notes and specifications on their Model 1115-B oscillator, hoping there might be some relevance to the Model 1120. Product specific information starts on page 8. http://www.ni6e.com/genrad/ Regards, Peter NI6E Max Robinson wrote: There must have been several different versions of this unit. The oscillator I have is 5 MHz. The frequency dividers in the rack I got it out of were discrete transistor construction. Seems to me the clock used a 25L6 although I don't remember how they derived the heater voltage. There was also a phase locked frequency multiplier with outputs at 10 MHz, 100 MHz and 1 GHz. The frequency divider module had outputs down to 1 PPS. After typing that I'm not sure the oscillator frequency is right. Maybe it's 1 MHz. I'm sure it's not 100 kHz. Regards. Max. K 4 O D S. ___ 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Bruce Griffiths [EMAIL PROTECTED] wrote: Max A capacitance bridge using a transformer would be a lot more stable than merely using the capacitance to vary the frequency of an LC oscillator. The advantage of a capacitive sensing technique over a light beam is that it has much simpler and potentially more stable mechanical system than when a the mercury colum interrupts a light beam. Unless of course on has the Mercury column move a moire grating or similar setup such as making the top of the mercury column a reflector in an interferometer system. Bruce Very clever! According to this web page, interferometry could give a resolution of 0.15 nm, or close to the radius of a silver atom: http://www.aerotech.com/products/engref/intexe.html This video shows the basic principle in case you want to make your own: http://www.metacafe.com/watch/1381543/laser_interferometer_homemade_for_20/ You can see from the movement of the fringes how sensitive interferometry can be. This should give unprecedented temperature control, so maybe someone has already done it. A google search gives lots of hits, but it is difficult to distinguish between controlling the termperature of something, and the need for accurate control of temperature to get stable fringes! Great idea! Regards, Mike Monett ___ 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] Restoring GR 1120-AB Frequency Standard
Gentlemen, Original poster is trying to RESTORE this entire old General Radio Standard ( a rack of equipment) to it's original glory. He simply needs a part, a unique thermoswitch or a way to fix it, not retrofit an atomic engine! This is a museum class instrument, 100kc. May I suggest start a new thread on the better/best merits/design of temperature control. Makes it rather difficult to follow a thread as the subject has changed. Respectfully Phil - Original Message - From: Mike Monett [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Friday, August 22, 2008 9:20 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Bruce Griffiths [EMAIL PROTECTED] wrote: Max A capacitance bridge using a transformer would be a lot more stable than merely using the capacitance to vary the frequency of an LC oscillator. The advantage of a capacitive sensing technique over a light beam is that it has much simpler and potentially more stable mechanical system than when a the mercury colum interrupts a light beam. Unless of course on has the Mercury column move a moire grating or similar setup such as making the top of the mercury column a reflector in an interferometer system. Bruce Very clever! According to this web page, interferometry could give a resolution of 0.15 nm, or close to the radius of a silver atom: http://www.aerotech.com/products/engref/intexe.html This video shows the basic principle in case you want to make your own: http://www.metacafe.com/watch/1381543/laser_interferometer_homemade_for_20/ You can see from the movement of the fringes how sensitive interferometry can be. This should give unprecedented temperature control, so maybe someone has already done it. A google search gives lots of hits, but it is difficult to distinguish between controlling the termperature of something, and the need for accurate control of temperature to get stable fringes! Great idea! Regards, Mike Monett ___ 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
phil wrote: Gentlemen, Original poster is trying to RESTORE this entire old General Radio Standard ( a rack of equipment) to it's original glory. He simply needs a part, a unique thermoswitch or a way to fix it, not retrofit an atomic engine! This is a museum class instrument, 100kc. May I suggest start a new thread on the better/best merits/design of temperature control. Makes it rather difficult to follow a thread as the subject has changed. My proposal to use capacitive sensing rather than conductive sensing would handle the electrode oxide issue. It is meant as a means to go around the sensing issue with parts at hand and only some new electronic design of very simple form, not the means to supercalibrate something. I guess this only shows that time-nuts are time-nuts... Cheers, Magnus ___ 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] Restoring GR 1120-AB Frequency Standard
Well, I won't cross that bridge until I am forced to. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] - Original Message - From: Bruce Griffiths [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, August 22, 2008 12:28 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Max A capacitance bridge using a transformer would be a lot more stable than merely using the capacitance to vary the frequency of an LC oscillator. The advantage of a capacitive sensing technique over a light beam is that it has much simpler and potentially more stable mechanical system than when a the mercury colum interrupts a light beam. Unless of course on has the Mercury column move a moire grating or similar setup such as making the top of the mercury column a reflector in an interferometer system. 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. ___ 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] Restoring GR 1120-AB Frequency Standard
- Original Message - From: Magnus Danielson [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, August 22, 2008 5:25 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard phil wrote: Gentlemen, Original poster is trying to RESTORE this entire old General Radio Standard ( a rack of equipment) to it's original glory. He simply needs a part, a unique thermoswitch or a way to fix it, not retrofit an atomic engine! This is a museum class instrument, 100kc. May I suggest start a new thread on the better/best merits/design of temperature control. Makes it rather difficult to follow a thread as the subject has changed. My proposal to use capacitive sensing rather than conductive sensing would handle the electrode oxide issue. It is meant as a means to go around the sensing issue with parts at hand and only some new electronic design of very simple form, not the means to supercalibrate something. I guess this only shows that time-nuts are time-nuts... Cheers, Magnus Magnus, Perhaps this will help understand why I made that comment. That old primary standard was quite a contraption. This things heyday was in the order of 1950's and used up into the 60's and some models into early 70's. Of course it was all tube equipment. My unit model was possibly a 620, it predated what Russ has (1100) but was quite similar in design. Russ's unit has all the multivibrators in one housing where mine was each separate. I think his is a 100kc oscillator and mine was 50kc. As I remember the one I had was in two 7-foot racks, a standard side and frequency measuring side. My oscillator was 50KC though about 300 dollars in the mid 6o's would have bought a 100kc quartz bar to upgrade it The unit had each module or circuit in a separate 19 rack space all averaging 8 inch high The main components, a power supply, oscillator (about 20 plus rack inches high by itself), separate multivibrators of 100kc, 10kc, 1kc, and 100 cycles. Yes they were called multivibrators though all tube. It also had a syncronometer at the top of the rack, better known as a clock. Apparently the crystal was rich in harmonics and they made use of it in this assembly. That clock ran off of the 1 kc output. The heart of the oscillator, main part of this contraption used a quartz bar about 3/8 of an inch square and about 2 inches long suspended on 4 springs. If I recall it was a single oven but it's specs called for about .01-degree regulation. I don't remember all the fine details, but it had many other components (all seperate rack units), a separate 5kc interpolation oscillator, amplifier, and even an 8-inch speaker to zero beat the standard to another unit, talking about phase lock! So as you can see, these vintage units only use/value is that of an antique or conversation piece. A 10811 would blow it away performance wise. Now with an understanding of that old antique, that discussion was like putting an electronic ignition in place of the old Ford Model T spark coil. You could, but .. You just search for the part. So it's not a time-nut issue as such other than appreciating the history or the evolution of time. I can see from the varied posts this is one heck of a super talented group. I guess we all get involved in something interesting and easily get carried away, as in the discussion. Granted you can do a given task many ways, and bantering ideas around is how things are born and perfected. Only problem is, it doesn't locate an original antique part, what he stated he wanted! That old GR stuff does occasionally show up, most free to haul off it's so massive. A bunch of the old vintage GR standard parts was listed as a lot on ebay some months ago. Someone asked what happened to my old GR stuff. I disposed of over 100 tons of old electronics that had accumulated including this old GR stuff. One of my sidelines was the used equipment business and the sales of tube stuff died. I had some 15,000 feet of junk as I call all this stuff. By the way, according to Bruce, that design of the old thermoswitch achieved resolutions as fine as .001 degrees. It would be hard to build any electronic sensor of any design that is that reliable and repeatable (.001 degree) with a one-time factory calibration good for a life exceeding 50 years without using a similar sensor design. The unit in question with the electrode in mercury design lasted about 50 years before showing it's age and misbehaving. Phil ___ 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] Restoring GR 1120-AB Frequency Standard
There must have been several different versions of this unit. The oscillator I have is 5 MHz. The frequency dividers in the rack I got it out of were discrete transistor construction. Seems to me the clock used a 25L6 although I don't remember how they derived the heater voltage. There was also a phase locked frequency multiplier with outputs at 10 MHz, 100 MHz and 1 GHz. The frequency divider module had outputs down to 1 PPS. After typing that I'm not sure the oscillator frequency is right. Maybe it's 1 MHz. I'm sure it's not 100 kHz. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] - Original Message - From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, August 22, 2008 10:15 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard - Original Message - From: Magnus Danielson [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, August 22, 2008 5:25 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard phil wrote: Gentlemen, Original poster is trying to RESTORE this entire old General Radio Standard ( a rack of equipment) to it's original glory. He simply needs a part, a unique thermoswitch or a way to fix it, not retrofit an atomic engine! This is a museum class instrument, 100kc. May I suggest start a new thread on the better/best merits/design of temperature control. Makes it rather difficult to follow a thread as the subject has changed. My proposal to use capacitive sensing rather than conductive sensing would handle the electrode oxide issue. It is meant as a means to go around the sensing issue with parts at hand and only some new electronic design of very simple form, not the means to supercalibrate something. I guess this only shows that time-nuts are time-nuts... Cheers, Magnus Magnus, Perhaps this will help understand why I made that comment. That old primary standard was quite a contraption. This things heyday was in the order of 1950's and used up into the 60's and some models into early 70's. Of course it was all tube equipment. My unit model was possibly a 620, it predated what Russ has (1100) but was quite similar in design. Russ's unit has all the multivibrators in one housing where mine was each separate. I think his is a 100kc oscillator and mine was 50kc. As I remember the one I had was in two 7-foot racks, a standard side and frequency measuring side. My oscillator was 50KC though about 300 dollars in the mid 6o's would have bought a 100kc quartz bar to upgrade it The unit had each module or circuit in a separate 19 rack space all averaging 8 inch high The main components, a power supply, oscillator (about 20 plus rack inches high by itself), separate multivibrators of 100kc, 10kc, 1kc, and 100 cycles. Yes they were called multivibrators though all tube. It also had a syncronometer at the top of the rack, better known as a clock. Apparently the crystal was rich in harmonics and they made use of it in this assembly. That clock ran off of the 1 kc output. The heart of the oscillator, main part of this contraption used a quartz bar about 3/8 of an inch square and about 2 inches long suspended on 4 springs. If I recall it was a single oven but it's specs called for about .01-degree regulation. I don't remember all the fine details, but it had many other components (all seperate rack units), a separate 5kc interpolation oscillator, amplifier, and even an 8-inch speaker to zero beat the standard to another unit, talking about phase lock! So as you can see, these vintage units only use/value is that of an antique or conversation piece. A 10811 would blow it away performance wise. Now with an understanding of that old antique, that discussion was like putting an electronic ignition in place of the old Ford Model T spark coil. You could, but .. You just search for the part. So it's not a time-nut issue as such other than appreciating the history or the evolution of time. I can see from the varied posts this is one heck of a super talented group. I guess we all get involved in something interesting and easily get carried away, as in the discussion. Granted you can do a given task many ways, and bantering ideas around is how things are born and perfected. Only problem is, it doesn't locate an original antique part, what he stated he wanted! That old GR stuff does occasionally show up, most free to haul off it's so massive. A bunch of the old vintage GR standard parts was listed as a lot on ebay some months ago. Someone asked what happened to my old GR stuff. I disposed of over 100
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Mike Monett wrote: [EMAIL PROTECTED] wrote: Phil, I didn't believe that the thermoswitch was the problem, at first, chiefly because of the simplicity of operation. Eventually, after checking wiring, a carbon resistor that is in series with the thermoswitch, and components around the inner oven control circuitry, I removed the thermoswitch to the bench. After hooking up to a ohmmeter and using a 60 watt light bulb as the heat source, I found that I could duplicate the a pulsating open / close as before. I first focused on the bulb leads and eventually completely removed the old leads and rebuilt each one and did all new soldering under magnification. The problem remains the same. I'm ready to move on at this point noting that this component failure has me stumped and that the fault is most likely internal to the thermoswitch (as strange as this seems). Years ago, when I first saw how internal temperature worked using the mercury thermometer switch, I remarked that it was one component that would never fail. HA! That statement came back to haunt me. Best, Russ I have been following this thread with some interest, as I expect to have similar equipment in the future. What is amazing is how you discovered the problem! Like you, I would not have believed a mercury switch could fail. But a quick search showed the contact can oxidize, and gave several patents aimed at solving the problem: 1. Reduction of oxides in a fluid-based switch - US Patent 7071432, 07/04/2006 Often, oxides may form within the switch and inhibit proper functioning of the switch. For example, the oxides may increase or decrease the surface tension of the liquid metal, which may increase or decrease the energy required for the switch to change state. Oxides can lead to poor switch performance, and even switch failure, because they lessen or prevent a switching fluid from wetting surfaces it is supposed to wet. Hmm... but capacitive sensing should still work well. Cheer, Magnus ___ 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] Restoring GR 1120-AB Frequency Standard
When I was at the university I saw and worked on a thermostatic switch that used a standard mercury thermometer. The little thing that clipped on to the thermometer was the capacitor in an oscillator. The detector for opening and closing the relay was a high Q tuned circuit. I saw them regularly because I had to keep teaching lab instructors how to tune them up before each use. In a controlled environment it might be possible to optimize such a circuit for stable operation and tight control. My intuition tells me that 1 degree is about as fine a control as you could get unless you had a very narrow range thermometer with a small capillary. You might be able to convert the existing thermostat to capacitive sensing. That is apparently what Magnus is suggesting. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] - Original Message - From: Magnus Danielson [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, August 21, 2008 12:00 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Mike Monett wrote: [EMAIL PROTECTED] wrote: Phil, I didn't believe that the thermoswitch was the problem, at first, chiefly because of the simplicity of operation. Eventually, after checking wiring, a carbon resistor that is in series with the thermoswitch, and components around the inner oven control circuitry, I removed the thermoswitch to the bench. After hooking up to a ohmmeter and using a 60 watt light bulb as the heat source, I found that I could duplicate the a pulsating open / close as before. I first focused on the bulb leads and eventually completely removed the old leads and rebuilt each one and did all new soldering under magnification. The problem remains the same. I'm ready to move on at this point noting that this component failure has me stumped and that the fault is most likely internal to the thermoswitch (as strange as this seems). Years ago, when I first saw how internal temperature worked using the mercury thermometer switch, I remarked that it was one component that would never fail. HA! That statement came back to haunt me. Best, Russ I have been following this thread with some interest, as I expect to have similar equipment in the future. What is amazing is how you discovered the problem! Like you, I would not have believed a mercury switch could fail. But a quick search showed the contact can oxidize, and gave several patents aimed at solving the problem: 1. Reduction of oxides in a fluid-based switch - US Patent 7071432, 07/04/2006 Often, oxides may form within the switch and inhibit proper functioning of the switch. For example, the oxides may increase or decrease the surface tension of the liquid metal, which may increase or decrease the energy required for the switch to change state. Oxides can lead to poor switch performance, and even switch failure, because they lessen or prevent a switching fluid from wetting surfaces it is supposed to wet. Hmm... but capacitive sensing should still work well. Cheer, Magnus ___ 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Max Robinson [EMAIL PROTECTED] wrote: When I was at the university I saw and worked on a thermostatic switch that used a standard mercury thermometer. The little thing that clipped on to the thermometer was the capacitor in an oscillator. The detector for opening and closing the relay was a high Q tuned circuit. I saw them regularly because I had to keep teaching lab instructors how to tune them up before each use. In a controlled environment it might be possible to optimize such a circuit for stable operation and tight control. My intuition tells me that 1 degree is about as fine a control as you could get unless you had a very narrow range thermometer with a small capillary. You might be able to convert the existing thermostat to capacitive sensing. That is apparently what Magnus is suggesting. Regards. Max. K 4 O D S. Optical might work better. Maybe use the lens and laser from an old CDROM. It might be fun getting it to focus on the mercury column through a round glass tube. Or maybe the glass wouldn't even pass the infrared. I got a bad burn once picking up an empty wine glass that was sitting beside a fireplace. But I understand new systems use a blue laser, which might work even better. I wonder what kind of temperature control it would give, and what the long-term drift might be. Sounds like a fun project. Regards, Mike Monett ___ 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] Restoring GR 1120-AB Frequency Standard
Hmmm. That sounds like something to be stored away for the day when my thermostat goes bad. Sounds like it would work. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] - Original Message - From: Mike Monett [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Thursday, August 21, 2008 2:07 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Max Robinson [EMAIL PROTECTED] wrote: When I was at the university I saw and worked on a thermostatic switch that used a standard mercury thermometer. The little thing that clipped on to the thermometer was the capacitor in an oscillator. The detector for opening and closing the relay was a high Q tuned circuit. I saw them regularly because I had to keep teaching lab instructors how to tune them up before each use. In a controlled environment it might be possible to optimize such a circuit for stable operation and tight control. My intuition tells me that 1 degree is about as fine a control as you could get unless you had a very narrow range thermometer with a small capillary. You might be able to convert the existing thermostat to capacitive sensing. That is apparently what Magnus is suggesting. Regards. Max. K 4 O D S. Optical might work better. Maybe use the lens and laser from an old CDROM. It might be fun getting it to focus on the mercury column through a round glass tube. Or maybe the glass wouldn't even pass the infrared. I got a bad burn once picking up an empty wine glass that was sitting beside a fireplace. But I understand new systems use a blue laser, which might work even better. I wonder what kind of temperature control it would give, and what the long-term drift might be. Sounds like a fun project. Regards, Mike Monett ___ 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Max A capacitance bridge using a transformer would be a lot more stable than merely using the capacitance to vary the frequency of an LC oscillator. The advantage of a capacitive sensing technique over a light beam is that it has much simpler and potentially more stable mechanical system than when a the mercury colum interrupts a light beam. Unless of course on has the Mercury column move a moire grating or similar setup such as making the top of the mercury column a reflector in an interferometer system. 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Phil, The details of the thermoswitch failure are not completely clear. Intermittently, the mercury column will pass the 78C point without causing circuit closure. Instead, a pulsating open / close with an internal resistance of 50K - 300K is observed. Circuit closure eventually happens at a temperature above 82C. Once an external failure, i.e. lead wiring, was ruled out, I used a borrowed microscope to view the internal structure of the thermoswitch. Unfortunately, this did not reveal the failure source. Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 9:33 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Neville, good answer. Perhaps the original poster could supply a photo of his switch, perhaps more suggestions could be made. I think we had an old gr-1100 at one time, it was a 100kc unit. Needless to say it was scrapped years ago and I'm sure it's been melted down and sent back to the usa in tin cans or cars by now! I'm curious as to how the switch failed. I'm assuming it was a sealed unit. Phil - Original Message - From: Neville Michie [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, August 19, 2008 7:46 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Hi, this is a second attempt at an answer, the first seemed to evaporate. Mercury-in -glass thermometers have formed the basis of a system of thermostats used constant temperature systems of very high performance. A major producer of contact thermometers was Jumo (maybe German). These thermometers had a thin wire that went down the capillary and contacted the mercury at the set temperature. The system could be accurate to 0.005 degree. The control algorithm is alien to modern EEs but used a large thermal mass and a fixed rate of heating to produce a slow temperature ramp. Fast response by the thermometer switching kept overshoot down to millidegrees. A cycle time of 5 or 10 seconds kept a very low amplitude temperature ramp running up and down with mean temperature held quite close. Locating the thermometer close to the heater caused a little over control which reduced overshoot and cycle amplitude. The thermometers had up to 30 mA run through the wire, but more modern units reduced this to 1mA. If the tip is corroded on your thermometer contact, maybe a higher resistance measuring circuit may still operate reliably. Good Luck with the unit, Neville Michie On 20/08/2008, at 9:17 AM, Mark Sims wrote: I suspect the only place you would find a replacement themoswitch is in another unit. I also doubt that any current mechanical switch will be anywhere near stable and accurate enough. I stand by my original comments: Built a solid state functional replacement in the same form factor as the original unit. It will be hidden inside the oven assembly where only you will know of the dastardly deed that you did. If you ever find a replacement switch, you can install it and bask in its originality. Until then, bask in its solid state patch enabled oscillatude. A non-original part that restores a device to operating condition is far superior to a dead unit... particularly if the part is not visible. There are lots of zillion dollar antique cars winning best-of-show with modern internal engine components (not to mention bondo and fiberglass under the paint). _ Be the filmmaker you always wanted to beearn how to burn a DVD with Windows. http://clk.atdmt.com/MRT/go/108588797/direct/01/ ___ 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 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Hi Neville, Voltage across the thermoswitch contacts in less than 10VAC. Current is 6-8 mA. Once in failure mode, the mercury column passes the 78C point without causing circuit closure. Instead, a rapidly pulsating open / close with an internal resistance of 50K - 300K is observed. Circuit closure eventually happens at a temperature above 82C. After this overtemp condition, the thermoswitch will perform normally for numerous cycles before going back into failure mode. Once I detected the intermittent thermoswitch failure, I increased voltage and current to see if this would restore reliability. Failures went from minutes and hours to about 12 hours and occasionally days but not good enough to declare success. I haven't increased voltage and current further as I feel that it better to replace the failing component. Thanks, Russ -Original Message- From: Neville Michie [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 7:46 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Hi, this is a second attempt at an answer, the first seemed to evaporate. Mercury-in -glass thermometers have formed the basis of a system of thermostats used constant temperature systems of very high performance. A major producer of contact thermometers was Jumo (maybe German). These thermometers had a thin wire that went down the capillary and contacted the mercury at the set temperature. The system could be accurate to 0.005 degree. The control algorithm is alien to modern EEs but used a large thermal mass and a fixed rate of heating to produce a slow temperature ramp. Fast response by the thermometer switching kept overshoot down to millidegrees. A cycle time of 5 or 10 seconds kept a very low amplitude temperature ramp running up and down with mean temperature held quite close. Locating the thermometer close to the heater caused a little over control which reduced overshoot and cycle amplitude. The thermometers had up to 30 mA run through the wire, but more modern units reduced this to 1mA. If the tip is corroded on your thermometer contact, maybe a higher resistance measuring circuit may still operate reliably. Good Luck with the unit, Neville Michie On 20/08/2008, at 9:17 AM, Mark Sims wrote: I suspect the only place you would find a replacement themoswitch is in another unit. I also doubt that any current mechanical switch will be anywhere near stable and accurate enough. I stand by my original comments: Built a solid state functional replacement in the same form factor as the original unit. It will be hidden inside the oven assembly where only you will know of the dastardly deed that you did. If you ever find a replacement switch, you can install it and bask in its originality. Until then, bask in its solid state patch enabled oscillatude. A non-original part that restores a device to operating condition is far superior to a dead unit... particularly if the part is not visible. There are lots of zillion dollar antique cars winning best-of-show with modern internal engine components (not to mention bondo and fiberglass under the paint). _ Be the filmmaker you always wanted to beearn how to burn a DVD with Windows. http://clk.atdmt.com/MRT/go/108588797/direct/01/ ___ 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 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] Restoring GR 1120-AB Frequency Standard
Russ, In other words, you sound like you are not 100% sure it's the switch. A shame you couldn't graph voltage and current going to the switch as it cycles. Is it possible a cap or something else is intermittently failing in the circuit. Again I'm assuming with that resistance there is something between it and the heater. Though I had one, I don't think I ever looked inside the thing. I have seen some similar units (I think what you have) that use an almost paper thin column of mercury. I would guess that is how they can achieve the fine resolution/precision. Phil - Original Message - From: [EMAIL PROTECTED] To: time-nuts@febo.com Cc: [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 2:34 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Phil, The details of the thermoswitch failure are not completely clear. Intermittently, the mercury column will pass the 78C point without causing circuit closure. Instead, a pulsating open / close with an internal resistance of 50K - 300K is observed. Circuit closure eventually happens at a temperature above 82C. Once an external failure, i.e. lead wiring, was ruled out, I used a borrowed microscope to view the internal structure of the thermoswitch. Unfortunately, this did not reveal the failure source. Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 9:33 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Neville, good answer. Perhaps the original poster could supply a photo of his switch, perhaps more suggestions could be made. I think we had an old gr-1100 at one time, it was a 100kc unit. Needless to say it was scrapped years ago and I'm sure it's been melted down and sent back to the usa in tin cans or cars by now! I'm curious as to how the switch failed. I'm assuming it was a sealed unit. Phil - Original Message - From: Neville Michie [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, August 19, 2008 7:46 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Hi, this is a second attempt at an answer, the first seemed to evaporate. Mercury-in -glass thermometers have formed the basis of a system of thermostats used constant temperature systems of very high performance. A major producer of contact thermometers was Jumo (maybe German). These thermometers had a thin wire that went down the capillary and contacted the mercury at the set temperature. The system could be accurate to 0.005 degree. The control algorithm is alien to modern EEs but used a large thermal mass and a fixed rate of heating to produce a slow temperature ramp. Fast response by the thermometer switching kept overshoot down to millidegrees. A cycle time of 5 or 10 seconds kept a very low amplitude temperature ramp running up and down with mean temperature held quite close. Locating the thermometer close to the heater caused a little over control which reduced overshoot and cycle amplitude. The thermometers had up to 30 mA run through the wire, but more modern units reduced this to 1mA. If the tip is corroded on your thermometer contact, maybe a higher resistance measuring circuit may still operate reliably. Good Luck with the unit, Neville Michie On 20/08/2008, at 9:17 AM, Mark Sims wrote: I suspect the only place you would find a replacement themoswitch is in another unit. I also doubt that any current mechanical switch will be anywhere near stable and accurate enough. I stand by my original comments: Built a solid state functional replacement in the same form factor as the original unit. It will be hidden inside the oven assembly where only you will know of the dastardly deed that you did. If you ever find a replacement switch, you can install it and bask in its originality. Until then, bask in its solid state patch enabled oscillatude. A non-original part that restores a device to operating condition is far superior to a dead unit... particularly if the part is not visible. There are lots of zillion dollar antique cars winning best-of-show with modern internal engine components (not to mention bondo and fiberglass under the paint). _ Be the filmmaker you always wanted to beearn how to burn a DVD with Windows. http://clk.atdmt.com/MRT/go/108588797/direct/01/ ___ 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
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Russ, Also could it be a cold solder joint on the tubes connections, possibly look good but have a high resistance. That could account for an intermittent as you are describing. Sometimes we overlook the simplest of things. Phil - Original Message - From: phil [EMAIL PROTECTED] To: time-nuts@febo.com; [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 3:26 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Russ, In other words, you sound like you are not 100% sure it's the switch. A shame you couldn't graph voltage and current going to the switch as it cycles. Is it possible a cap or something else is intermittently failing in the circuit. Again I'm assuming with that resistance there is something between it and the heater. Though I had one, I don't think I ever looked inside the thing. I have seen some similar units (I think what you have) that use an almost paper thin column of mercury. I would guess that is how they can achieve the fine resolution/precision. Phil - Original Message - From: [EMAIL PROTECTED] To: time-nuts@febo.com Cc: [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 2:34 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Phil, The details of the thermoswitch failure are not completely clear. Intermittently, the mercury column will pass the 78C point without causing circuit closure. Instead, a pulsating open / close with an internal resistance of 50K - 300K is observed. Circuit closure eventually happens at a temperature above 82C. Once an external failure, i.e. lead wiring, was ruled out, I used a borrowed microscope to view the internal structure of the thermoswitch. Unfortunately, this did not reveal the failure source. Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 9:33 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Neville, good answer. Perhaps the original poster could supply a photo of his switch, perhaps more suggestions could be made. I think we had an old gr-1100 at one time, it was a 100kc unit. Needless to say it was scrapped years ago and I'm sure it's been melted down and sent back to the usa in tin cans or cars by now! I'm curious as to how the switch failed. I'm assuming it was a sealed unit. Phil - Original Message - From: Neville Michie [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, August 19, 2008 7:46 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Hi, this is a second attempt at an answer, the first seemed to evaporate. Mercury-in -glass thermometers have formed the basis of a system of thermostats used constant temperature systems of very high performance. A major producer of contact thermometers was Jumo (maybe German). These thermometers had a thin wire that went down the capillary and contacted the mercury at the set temperature. The system could be accurate to 0.005 degree. The control algorithm is alien to modern EEs but used a large thermal mass and a fixed rate of heating to produce a slow temperature ramp. Fast response by the thermometer switching kept overshoot down to millidegrees. A cycle time of 5 or 10 seconds kept a very low amplitude temperature ramp running up and down with mean temperature held quite close. Locating the thermometer close to the heater caused a little over control which reduced overshoot and cycle amplitude. The thermometers had up to 30 mA run through the wire, but more modern units reduced this to 1mA. If the tip is corroded on your thermometer contact, maybe a higher resistance measuring circuit may still operate reliably. Good Luck with the unit, Neville Michie On 20/08/2008, at 9:17 AM, Mark Sims wrote: I suspect the only place you would find a replacement themoswitch is in another unit. I also doubt that any current mechanical switch will be anywhere near stable and accurate enough. I stand by my original comments: Built a solid state functional replacement in the same form factor as the original unit. It will be hidden inside the oven assembly where only you will know of the dastardly deed that you did. If you ever find a replacement switch, you can install it and bask in its originality. Until then, bask in its solid state patch enabled oscillatude. A non-original part that restores a device to operating condition is far superior to a dead unit... particularly if the part is not visible. There are lots of zillion dollar antique cars winning best-of-show with modern internal engine components (not to mention bondo and fiberglass under the paint). _ Be the filmmaker you always wanted to beearn how to burn a DVD
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Phil, I didn't believe that the thermoswitch was the problem, at first, chiefly because of the simplicity of operation. Eventually, after checking wiring, a carbon resistor that is in series with the thermoswitch, and components around the inner oven control circuitry, I removed the thermoswitch to the bench. After hooking up to a ohmmeter and using a 60 watt light bulb as the heat source, I found that I could duplicate the a pulsating open / close as before. I first focused on the bulb leads and eventually completely removed the old leads and rebuilt each one and did all new soldering under magnification. The problem remains the same. I'm ready to move on at this point noting that this component failure has me stumped and that the fault is most likely internal to the thermoswitch (as strange as this seems). Years ago, when I first saw how internal temperature worked using the mercury thermometer switch, I remarked that it was one component that would never fail. HA! That statement came back to haunt me. Best, Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wed, 20 Aug 2008 3:45 am Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Russ, Also could it be a cold solder joint on the tubes connections, possibly look good but have a high resistance. That could account for an intermittent as you are describing. Sometimes we overlook the simplest of things. Phil - Original Message - From: phil [EMAIL PROTECTED] To: time-nuts@febo.com; [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 3:26 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Russ, In other words, you sound like you are not 100% sure it's the switch. A shame you couldn't graph voltage and current going to the switch as it cycles. Is it possible a cap or something else is intermittently failing in the circuit. Again I'm assuming with that resistance there is something between it and the heater. Though I had one, I don't think I ever looked inside the thing. I have seen some similar units (I think what you have) that use an almost paper thin column of mercury. I would guess that is how they can achieve the fine resolution/precision. Phil - Original Message - From: [EMAIL PROTECTED] To: time-nuts@febo.com Cc: [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 2:34 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Phil, The details of the thermoswitch failure are not completely clear. Intermittently, the mercury column will pass the 78C point without causing circuit closure. Instead, a pulsating open / close with an internal resistance of 50K - 300K is observed. Circuit closure eventually happens at a temperature above 82C. Once an external failure, i.e. lead wiring, was ruled out, I used a borrowed microscope to view the internal structure of the thermoswitch. Unfortunately, this did not reveal the failure source. Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 9:33 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Neville, good answer. Perhaps the original poster could supply a photo of his switch, perhaps more suggestions could be made. I think we had an old gr-1100 at one time, it was a 100kc unit. Needless to say it was scrapped years ago and I'm sure it's been melted down and sent back to the usa in tin cans or cars by now! I'm curious as to how the switch failed. I'm assuming it was a sealed unit. Phil - Original Message - From: Neville Michie [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, August 19, 2008 7:46 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Hi, this is a second attempt at an answer, the first seemed to evaporate. Mercury-in -glass thermometers have formed the basis of a system of thermostats used constant temperature systems of very high performance. A major producer of contact thermometers was Jumo (maybe German). These thermometers had a thin wire that went down the capillary and contacted the mercury at the set temperature. The system could be accurate to 0.005 degree. The control algorithm is alien to modern EEs but used a large thermal mass and a fixed rate of heating to produce a slow temperature ramp. Fast response by the thermometer switching kept overshoot down to millidegrees. A cycle time of 5 or 10 seconds kept a very low amplitude temperature ramp running up and down with mean temperature held quite close. Locating the thermometer close to the heater caused a little over control which reduced overshoot and cycle amplitude. The thermometers had up to 30 mA run through the wire, but more modern units reduced
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
[EMAIL PROTECTED] wrote: Phil, I didn't believe that the thermoswitch was the problem, at first, chiefly because of the simplicity of operation. Eventually, after checking wiring, a carbon resistor that is in series with the thermoswitch, and components around the inner oven control circuitry, I removed the thermoswitch to the bench. After hooking up to a ohmmeter and using a 60 watt light bulb as the heat source, I found that I could duplicate the a pulsating open / close as before. I first focused on the bulb leads and eventually completely removed the old leads and rebuilt each one and did all new soldering under magnification. The problem remains the same. I'm ready to move on at this point noting that this component failure has me stumped and that the fault is most likely internal to the thermoswitch (as strange as this seems). Years ago, when I first saw how internal temperature worked using the mercury thermometer switch, I remarked that it was one component that would never fail. HA! That statement came back to haunt me. Best, Russ I have been following this thread with some interest, as I expect to have similar equipment in the future. What is amazing is how you discovered the problem! Like you, I would not have believed a mercury switch could fail. But a quick search showed the contact can oxidize, and gave several patents aimed at solving the problem: 1. Reduction of oxides in a fluid-based switch - US Patent 7071432, 07/04/2006 Often, oxides may form within the switch and inhibit proper functioning of the switch. For example, the oxides may increase or decrease the surface tension of the liquid metal, which may increase or decrease the energy required for the switch to change state. Oxides can lead to poor switch performance, and even switch failure, because they lessen or prevent a switching fluid from wetting surfaces it is supposed to wet. 2. Preventing corrosion degradation in a fluid-based switch - United States Patent 6781074, 08/24/2004 Liquid metal switches rely on the cleanness of the liquid metal for good performance. If the liquid metal forms oxide films or other types of corrosion product buildup within the switch, the proper functioning or performance of the switch may degrade or be inhibited. For example, the oxide film or other corrosion products may increase the surface tension of the liquid metal, which may increase the energy required for the switch to change state. Films of oxide and other corrosion products may increase the tendency for the liquid metal to wet to the substrate between switch contacts, thereby increasing undesirable short circuits in the switching operation. Build up of oxide and other corrosion products may also degrade the ability of the liquid metal to wet to the switch contacts, and thereby may increase the probability of undesirable open circuits in the switching operation. This is very interesting. Thanks for posting your experience. Best Regards, Mike Monett ___ 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] Restoring GR 1120-AB Frequency Standard
Russ Do you have a photo, would it be possible to build? I have a few flasks of mercury and a few 10's of thousands of mercury wetted relays that some could be cannibalized for electrodes. The trick here is how thin is that column of mercury. My guess the thinner the column, the finer the resolution or the more it will travel with a small temp swing. Better yet, possible to cut that thing open and fix it. I know that's more time than it's worth. Another thought, if the contacts have corroded in the mercury, perhaps from contamination, would it be possible to burn the contamination off. Thinking of excessive voltage/current. Perhaps making it arc internally. Trick would be to limit current not to explode the thing, perhaps using a charged capacitor. Just a thought. Oh, do you have the whole rack, all dividers and the clock? I bet the old clock alone is worth a thousand bucks today. Seems like it was driven by 1 KC. My old standard was complete, a 5 or 6 foot rack and came out of an old Hamerland Radio plant. phil - Original Message - From: [EMAIL PROTECTED] To: time-nuts@febo.com Cc: [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 4:16 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Phil, I didn't believe that the thermoswitch was the problem, at first, chiefly because of the simplicity of operation. Eventually, after checking wiring, a carbon resistor that is in series with the thermoswitch, and components around the inner oven control circuitry, I removed the thermoswitch to the bench. After hooking up to a ohmmeter and using a 60 watt light bulb as the heat source, I found that I could duplicate the a pulsating open / close as before. I first focused on the bulb leads and eventually completely removed the old leads and rebuilt each one and did all new soldering under magnification. The problem remains the same. I'm ready to move on at this point noting that this component failure has me stumped and that the fault is most likely internal to the thermoswitch (as strange as this seems). Years ago, when I first saw how internal temperature worked using the mercury thermometer switch, I remarked that it was one component that would never fail. HA! That statement came back to haunt me. Best, Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wed, 20 Aug 2008 3:45 am Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Russ, Also could it be a cold solder joint on the tubes connections, possibly look good but have a high resistance. That could account for an intermittent as you are describing. Sometimes we overlook the simplest of things. Phil - Original Message - From: phil [EMAIL PROTECTED] To: time-nuts@febo.com; [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 3:26 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Russ, In other words, you sound like you are not 100% sure it's the switch. A shame you couldn't graph voltage and current going to the switch as it cycles. Is it possible a cap or something else is intermittently failing in the circuit. Again I'm assuming with that resistance there is something between it and the heater. Though I had one, I don't think I ever looked inside the thing. I have seen some similar units (I think what you have) that use an almost paper thin column of mercury. I would guess that is how they can achieve the fine resolution/precision. Phil - Original Message - From: [EMAIL PROTECTED] To: time-nuts@febo.com Cc: [EMAIL PROTECTED] Sent: Wednesday, August 20, 2008 2:34 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Phil, The details of the thermoswitch failure are not completely clear. Intermittently, the mercury column will pass the 78C point without causing circuit closure. Instead, a pulsating open / close with an internal resistance of 50K - 300K is observed. Circuit closure eventually happens at a temperature above 82C. Once an external failure, i.e. lead wiring, was ruled out, I used a borrowed microscope to view the internal structure of the thermoswitch. Unfortunately, this did not reveal the failure source. Russ -Original Message- From: phil [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 9:33 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard Neville, good answer. Perhaps the original poster could supply a photo of his switch, perhaps more suggestions could be made. I think we had an old gr-1100 at one time, it was a 100kc unit. Needless to say it was scrapped years ago and I'm sure it's been melted down and sent back to the usa in tin cans or cars by now! I'm curious as to how the switch failed. I'm assuming it was a sealed unit. Phil
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
phil wrote: Russ Do you have a photo, would it be possible to build? I have a few flasks of mercury and a few 10's of thousands of mercury wetted relays that some could be cannibalized for electrodes. The trick here is how thin is that column of mercury. My guess the thinner the column, the finer the resolution or the more it will travel with a small temp swing. Better yet, possible to cut that thing open and fix it. I know that's more time than it's worth. Another thought, if the contacts have corroded in the mercury, perhaps from contamination, would it be possible to burn the contamination off. Thinking of excessive voltage/current. Perhaps making it arc internally. Trick would be to limit current not to explode the thing, perhaps using a charged capacitor. Just a thought. Oh, do you have the whole rack, all dividers and the clock? I bet the old clock alone is worth a thousand bucks today. Seems like it was driven by 1 KC. My old standard was complete, a 5 or 6 foot rack and came out of an old Hamerland Radio plant. phil Phil NBS used platinum wires in their mercury toluene thermoregulators. These were constructed from pyrex as it proved more stable than stainless steel. These themoregulators had a sensitivity of about 0.001C and were used to regulate the temperature of oil baths, 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
phil wrote: Bruce, what was the diameter or how was the column situated to give those resolutions. Phil The thermoregulator consisted of a horizontal ring tube filled with toluene connected to a 13 long J -tube filled with mercury and containing a capillary section at the top. The top contact consisted of platinum wire within and parallel to the capillary section, the mercury entered the capillary section and made contact with the tip of the vertical platinum wire therein. The other contact was made via a piece of platinum wire sealed through the side of the glass tube below the capillary section. Thus the top contact platinum wire fine enough to fit within the capillary section of the J tube and to a first approximation the diameter has no effect on the sensitivity which is due to the relatively high thermal expansion of the (highly flammable and somewhat toxic) toluene. Platinum and iron have the advantage that they do not directly form amalgams on contact with mercury and are thus not embrittled by amalgamation. However amalgams of platinum and iron can be formed electrochemically. I have a couple of illustrations of such thermoregulators which I can scan if you wish. 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
Bruce, nuf said, in that case it's the expansion of toluene, not the mercury. Can easily see how that would work, actually rather ingenious. As always, more than one way to do something. Thanks, Phil - Original Message - From: Bruce Griffiths [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, August 20, 2008 7:05 AM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard phil wrote: Bruce, what was the diameter or how was the column situated to give those resolutions. Phil The thermoregulator consisted of a horizontal ring tube filled with toluene connected to a 13 long J -tube filled with mercury and containing a capillary section at the top. The top contact consisted of platinum wire within and parallel to the capillary section, the mercury entered the capillary section and made contact with the tip of the vertical platinum wire therein. The other contact was made via a piece of platinum wire sealed through the side of the glass tube below the capillary section. Thus the top contact platinum wire fine enough to fit within the capillary section of the J tube and to a first approximation the diameter has no effect on the sensitivity which is due to the relatively high thermal expansion of the (highly flammable and somewhat toxic) toluene. Platinum and iron have the advantage that they do not directly form amalgams on contact with mercury and are thus not embrittled by amalgamation. However amalgams of platinum and iron can be formed electrochemically. I have a couple of illustrations of such thermoregulators which I can scan if you wish. 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. ___ 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] Restoring GR 1120-AB Frequency Standard
Hi Mike, Yes I feel that you have nailed the root cause of the failure. That explains the failures observed here. Thanks and Best Regards, Russ -Original Message- From: Mike Monett [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Wed, 20 Aug 2008 5:14 am Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard [EMAIL PROTECTED] wrote: Phil, I didn't believe that the thermoswitch was the problem, at first, chiefly because of the simplicity of operation. Eventually, after checking wiring, a carbon resistor that is in series with the thermoswitch, and components around the inner oven control circuitry, I removed the thermoswitch to the bench. After hooking up to a ohmmeter and using a 60 watt light bulb as the heat source, I found that I could duplicate the a pulsating open / close as before. I first focused on the bulb leads and eventually completely removed the old leads and rebuilt each one and did all new soldering under magnification. The problem remains the same. I'm ready to move on at this point noting that this component failure has me stumped and that the fault is most likely internal to the thermoswitch (as strange as this seems). Years ago, when I first saw how internal temperature worked using the mercury thermometer switch, I remarked that it was one component that would never fail. HA! That statement came back to haunt me. Best, Russ I have been following this thread with some interest, as I expect to have similar equipment in the future. What is amazing is how you discovered the problem! Like you, I would not have believed a mercury switch could fail. But a quick search showed the contact can oxidize, and gave several patents aimed at solving the problem: 1. Reduction of oxides in a fluid-based switch - US Patent 7071432, 07/04/2006 Often, oxides may form within the switch and inhibit proper functioning of the switch. For example, the oxides may increase or decrease the surface tension of the liquid metal, which may increase or decrease the energy required for the switch to change state. Oxides can lead to poor switch performance, and even switch failure, because they lessen or prevent a switching fluid from wetting surfaces it is supposed to wet. 2. Preventing corrosion degradation in a fluid-based switch - United States Patent 6781074, 08/24/2004 Liquid metal switches rely on the cleanness of the liquid metal for good performance. If the liquid metal forms oxide films or other types of corrosion product buildup within the switch, the proper functioning or performance of the switch may degrade or be inhibited. For example, the oxide film or other corrosion products may increase the surface tension of the liquid metal, which may increase the energy required for the switch to change state. Films of oxide and other corrosion products may increase the tendency for the liquid metal to wet to the substrate between switch contacts, thereby increasing undesirable short circuits in the switching operation. Build up of oxide and other corrosion products may also degrade the ability of the liquid metal to wet to the switch contacts, and thereby may increase the probability of undesirable open circuits in the switching operation. This is very interesting. Thanks for posting your experience. Best Regards, Mike Monett ___ 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] Restoring GR 1120-AB Frequency Standard - Need assist...
I am in the last stage of restoring a 1964 General Radio Frequency Standard Model 1120-AB. I'm having trouble getting the inner oven to work propoerly and the problem has been traced to a defective thermostat in the inner oven. In checking, the thermostat is a thermoswitch manufactured by Princo and is no longer available. My options appear to be: 1. locate a working GR Standard Frequency Oscillator (1113-A) and replace the entire chassis. 2. locate a non-working GR Frequency Oscillator and part it out as needed 3. find a suitable replacement for the original thermoswitch (78 C - closes circuit when temperature is reached) I was wondering if anyone on this list has any sources or leads for #1 and #2 and any opinions on a source for #3. Thanks Russ WA3FRP ___ 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] Restoring GR 1120-AB Frequency Standard - Need assist...
Hello Russ, Well, depending upon the size requirement of the thermal switch, I would consider trying to retro-fit. One company that makes such things is TEMPCO [ [1]http://www.tempco.com ]. They have several different kinds and even one model that is adjustable. There is a nice pictorial short-form PDF catalog that gives a clear picture of their temperature switches. Here is the URL for that : [2]http://www.tempco.com/Intro2008small.pdf See the 31st page. No doubt there are other manufacturers but this is the only one that comes to mind at the moment. As for #1 or #2 questions, I would think of those as a last ditch effort. BillWB6BNQ [EMAIL PROTECTED] wrote: I am in the last stage of restoring a 1964 General Radio Frequency Standard Model 1120-AB. I'm having trouble getting the inner oven to work propoerly and the problem has been traced to a defective thermostat in the inner oven. In checking, the thermostat is a thermoswitch manufactured by Princo and is no longer available. My options appear to be: 1. locate a working GR Standard Frequency Oscillator (1113-A) and replace the entire chassis. 2. locate a non-working GR Frequency Oscillator and part it out as needed 3. find a suitable replacement for the original thermoswitch (78 C - closes circuit when temperature is reached) I was wondering if anyone on this list has any sources or leads for #1 and #2 and any opinions on a source for #3. Thanks Russ WA3FRP ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to [3]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. References 1. http://www.tempco.com/ 2. http://www.tempco.com/Intro2008small.pdf 3. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ 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] Restoring GR 1120-AB Frequency Standard - Need
The original thermoswitch sounds like is is a mechanical switch, so it can't be all that accurate or stable. I would use something like one of those TO-92 temperature sensor chips. I would probably use a 8 pin micro with an A/D to read it and drive a reed relay (or transistor). Analog people would use a comparator and voltage reference chip/pot. _ See what people are saying about Windows Live. Check out featured posts. http://www.windowslive.com/connect?ocid=TXT_TAGLM_WL_connect2_082008 ___ 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] Restoring GR 1120-AB Frequency Standard - Need
Sorry for missing enough detail on the original thermoswitch. The original thermoswitch was a unique design that I have not seen elsewhere. The Princo thermoswitch was a modified mercury thermometer with two electrodes installed. When the temperature rises, the column of mercury comes into contact with both electrodes and completes the electric circuit. The inner oven stays within +/-0.05 degree C of 78C. Since the design involved a mercury thermometer, the form factor is 0.25 by 4.25 inches. -Original Message- From: Mark Sims [EMAIL PROTECTED] To: time-nuts@febo.com Sent: Tue, 19 Aug 2008 1:54 pm Subject: [time-nuts] Restoring GR 1120-AB Frequency Standard - Need The original thermoswitch sounds like is is a mechanical switch, so it can't be all that accurate or stable. I would use something like one of those TO-92 temperature sensor chips. I would probably use a 8 pin micro with an A/D to read it and drive a reed relay (or transistor). Analog people would use a comparator and voltage reference chip/pot. _ See what people are saying about Windows Live. Check out featured posts. http://www.windowslive.com/connect?ocid=TXT_TAGLM_WL_connect2_082008 ___ 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.
Re: [time-nuts] Restoring GR 1120-AB Frequency Standard - Needassist...
Hi Bill, The Tempco units look great. My original Google search came up with similar Fenwal units that are a bit larger sizewise. The size of the Tempco units appears to be a fit into the space reserved for the original thermoswitch. Thanks for the assist! 73 Russ WA3FRP -Original Message- From: WB6BNQ [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tue, 19 Aug 2008 2:06 pm Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard - Needassist... Russ, Here is the actual catalog PDF page [1]http://www.tempco.com/Catalog/Section%2013-pdf/Surface_Mount_Thermos tats.pdf Their site sucks for navigation and is very unclear, at first blush, on how to get to the meat. But I finally did find it. The above link has all the data on the variable model and the one I was thinking of (second item) which is the surface mount model. BillWB6BNQ Bill WB6BNQ wrote: Hello Russ, Well, depending upon the size requirement of the thermal switch, I would consider trying to retro-fit. One company that makes such things is TEMPCO [ [1][2]http://www.tempco.com ]. They have several different kinds and even one model that is adjustable. There is a nice pictorial short-form PDF catalog that gives a clear picture of their temperature switches. Here is the URL for that : [2][3]http://www.tempco.com/Intro2008small.pdf See the 31st page. No doubt there are other manufacturers but this is the only one that comes to mind at the moment. As for #1 or #2 questions, I would think of those as a last ditch effort. BillWB6BNQ [EMAIL PROTECTED] wrote: I am in the last stage of restoring a 1964 General Radio Frequency Standard Model 1120-AB. I'm having trouble getting the inner oven to work propoerly and the problem has been traced to a defective thermostat in the inner oven. In checking, the thermostat is a thermoswitch manufactured by Princo and is no longer available. My options appear to be: 1. locate a working GR Standard Frequency Oscillator (1113-A) and replace the entire chassis. 2. locate a non-working GR Frequency Oscillator and part it out as needed 3. find a suitable replacement for the original thermoswitch (78 C - closes circuit when temperature is reached) I was wondering if anyone on this list has any sources or leads for #1 and #2 and any opinions on a source for #3. Thanks Russ WA3FRP ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to [3][4]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. References 1. [5]http://www.tempco.com/ 2. [6]http://www.tempco.com/Intro2008small.pdf 3. [7]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to [8]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. References 1. http://www.tempco.com/Catalog/Section%2013-pdf/Surface_Mount_Thermostats.pdf 2. http://www.tempco.com/ 3. http://www.tempco.com/Intro2008small.pdf 4. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts 5. http://www.tempco.com/ 6. http://www.tempco.com/Intro2008small.pdf 7. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts 8. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ 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.
