Re: [time-nuts] Cheap Rubidium (heatpipe cooling for)
At 12:00 PM + 12/27/09, time-nuts-requ...@febo.com wrote: Date: Sat, 26 Dec 2009 17:04:46 -0700 From: Robert Darlington rdarling...@gmail.com Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for) To: Discussion of precise time and frequency measurement time-nuts@febo.com My comments are in-line, below On Fri, Dec 25, 2009 at 4:38 PM, Joe Gwinn joegw...@comcast.net wrote: At 12:45 AM + 12/25/09, time-nuts-requ...@febo.com wrote: Date: Thu, 24 Dec 2009 17:14:38 -0700 From: Robert Darlington rdarling...@gmail.com Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for) To: Discussion of precise time and frequency measurement time-nuts@febo.com On Thu, Dec 24, 2009 at 1:32 PM, Bob Camp li...@cq.nu wrote: Hi A heat pipe might work if the fluid had a sufficiently low boiling point. The working fluid in a heat pipe will boil at every temperature above its melting point. Well, I've been thinking about this, and I used the term heat pipe too loosely. Both the one- and two-pipe systems mentioned here have no wicks, and so technically are two-phase thermosyphons, which depend on gravity to circulate vapor and condensate. A true heat pipe has a wick, and will work in zero gravity. One gets significant heat transfer by phase change so long as the vapor pressure in the heat input end is high enough to generate enough vapor to carry the thermal power flow, and this makes the pipe isothermal. However the temperature (although constant along the pipe) varies with the thermal power flow (in thermal watts) being carried. What I'm looking for is related but different: A device where the heat transfer capacity varies sharply with temperature, so that there is a range of heat transfer rates over which the input-end temperature will be substantially constant. This is why I envision the fluid boiling (versus evaporating), which is actually out of the operating regime of a true heat pipe. I tend to use water because it's cheap, but have made them with 3M engineered fluids, Fluorinert, and denatured alcohol. Fluorinert. I think that's what the expensive commercial CPU-cooling heatpipes use. $1000 a gallon! Or $5 a drum when you buy it at a salvage auction. That explains why low-end heatpipes use alcohol or acetone. Actually, one ought to be able to use the freon intended for automobile air conditioners, for a whole lot less money, even new. I've found that ordinary solder works just fine. A trick to make these things easy to build is to use a ball valve at the top (I'm assuming there is a top and we're going with gravity return because it's simple). I've got a few that are still under vacuum for several years now in this configuration. My giant heat pipe of doom is a 10 foot stick of 1/2 copper with a ball valve at one end and an end cap at the other. There is perhaps 100ml water in there total, and no air. You can either boil the liquid until it builds up a nice head of steam, or go the easy way and pull a vacuum with a pump and just close the valve. I wouldn't have thought that an ordinary ball valve would be tight enough, allowing the water to escape and the air enter, slowly, although I suppose one can replace the water if it comes to that. Mine have been running for a few years with no sign of needing to be pumped down again. They just work. But I think people want to build this exactly once, so I followed refrigeration practice. A properly made hermetically sealed refrigeration system keeps its working fluid essentially forever. I suppose one can use a refrigeration fill valve, say from an automobile air conditioning system, but these all leak to some degree. Is the ball valve anything special? Nope, just whatever was on the shelf at the local hardware store. Stainless ball with brass valve body. Teflon bearing surface. Ahh. A quarter-turn ball valve, used as a cutoff. The term ball valve isn't quite precise in plumbing parlance. These are very good, but still they are not hermetic, and will over decades (if not a few years) lose their working fluid. I bet that while water will be contained, freon will diffuse right through the teflon seal of the ball valve. So, there's the tradeoff. These things are incredible. If you pack snow around the end of this thing, the other end that is ten feet away gets cold almost immediately. They want to stay isothermal and the heat transfer is at the speed of sound through the working fluid. Delays are introduced because you're dealing with a thermal mass of copper pipe that needs to change temperature along with the working fluid so it's not quite instant, but still about 10,000 times faster heat transfer than copper by itself. They are certainly handy for getting heat out of confined spaces. What is the purpose of the heatpipe of doom? Education? Education, fun, and then
[time-nuts] Fluke (Montronics) Model 207-5 WWVB Receiver/Comparator
Hello Group Members, I have a Fluke (Montronics) Model 207-5 WWVB Receiver/Comparator with various problems to many to mention on this list, if someone has any experience with this model and would like to help out please contact me off list salc...@rogers.comthank you for helping out. Sal C. Cornacchia Electronic RF Microwave Engineer (Ret.) ___ 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] Cheap Rubidium (heatpipe cooling for)
Hi The tip it and listen to it slam test is a standard way of checking out a triple point of water cell for basically the same reason (you check the vacuum. Of course since a TWP cell is thin glass and not a nice metal pipe, you *may* break the seal by testing it Bob On Dec 27, 2009, at 9:33 AM, Joe Gwinn wrote: At 12:00 PM + 12/27/09, time-nuts-requ...@febo.com wrote: Date: Sat, 26 Dec 2009 17:04:46 -0700 From: Robert Darlington rdarling...@gmail.com Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for) To: Discussion of precise time and frequency measurement time-nuts@febo.com My comments are in-line, below On Fri, Dec 25, 2009 at 4:38 PM, Joe Gwinn joegw...@comcast.net wrote: At 12:45 AM + 12/25/09, time-nuts-requ...@febo.com wrote: Date: Thu, 24 Dec 2009 17:14:38 -0700 From: Robert Darlington rdarling...@gmail.com Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for) To: Discussion of precise time and frequency measurement time-nuts@febo.com On Thu, Dec 24, 2009 at 1:32 PM, Bob Camp li...@cq.nu wrote: Hi A heat pipe might work if the fluid had a sufficiently low boiling point. The working fluid in a heat pipe will boil at every temperature above its melting point. Well, I've been thinking about this, and I used the term heat pipe too loosely. Both the one- and two-pipe systems mentioned here have no wicks, and so technically are two-phase thermosyphons, which depend on gravity to circulate vapor and condensate. A true heat pipe has a wick, and will work in zero gravity. One gets significant heat transfer by phase change so long as the vapor pressure in the heat input end is high enough to generate enough vapor to carry the thermal power flow, and this makes the pipe isothermal. However the temperature (although constant along the pipe) varies with the thermal power flow (in thermal watts) being carried. What I'm looking for is related but different: A device where the heat transfer capacity varies sharply with temperature, so that there is a range of heat transfer rates over which the input-end temperature will be substantially constant. This is why I envision the fluid boiling (versus evaporating), which is actually out of the operating regime of a true heat pipe. I tend to use water because it's cheap, but have made them with 3M engineered fluids, Fluorinert, and denatured alcohol. Fluorinert. I think that's what the expensive commercial CPU-cooling heatpipes use. $1000 a gallon! Or $5 a drum when you buy it at a salvage auction. That explains why low-end heatpipes use alcohol or acetone. Actually, one ought to be able to use the freon intended for automobile air conditioners, for a whole lot less money, even new. I've found that ordinary solder works just fine. A trick to make these things easy to build is to use a ball valve at the top (I'm assuming there is a top and we're going with gravity return because it's simple). I've got a few that are still under vacuum for several years now in this configuration. My giant heat pipe of doom is a 10 foot stick of 1/2 copper with a ball valve at one end and an end cap at the other. There is perhaps 100ml water in there total, and no air. You can either boil the liquid until it builds up a nice head of steam, or go the easy way and pull a vacuum with a pump and just close the valve. I wouldn't have thought that an ordinary ball valve would be tight enough, allowing the water to escape and the air enter, slowly, although I suppose one can replace the water if it comes to that. Mine have been running for a few years with no sign of needing to be pumped down again. They just work. But I think people want to build this exactly once, so I followed refrigeration practice. A properly made hermetically sealed refrigeration system keeps its working fluid essentially forever. I suppose one can use a refrigeration fill valve, say from an automobile air conditioning system, but these all leak to some degree. Is the ball valve anything special? Nope, just whatever was on the shelf at the local hardware store. Stainless ball with brass valve body. Teflon bearing surface. Ahh. A quarter-turn ball valve, used as a cutoff. The term ball valve isn't quite precise in plumbing parlance. These are very good, but still they are not hermetic, and will over decades (if not a few years) lose their working fluid. I bet that while water will be contained, freon will diffuse right through the teflon seal of the ball valve. So, there's the tradeoff. These things are incredible. If you pack snow around the end of this thing, the other end that is ten feet away gets cold almost immediately. They want to stay isothermal and the heat transfer is at the speed of sound through the working fluid. Delays are introduced because you're dealing with a thermal
Re: [time-nuts] Cheap Rubidium (TEC devices)
Hi Just in case anybody else is also looking for TEC's: The eplace has a number of Asian sellers with 100 to 150 W (power not Q) TEC's in the $3.xx to $5.xx range for 10 to 20 pieces delivered to the US. Assuming they are functional, that looks like better deal than scrapping out brand new gear to get them. Of course garage sale acquisitions probably would be the cheaper still. Bob On Dec 25, 2009, at 10:58 PM, J. Forster wrote: That's a significantly bigger one than I got. -John = See: http://www.walgreens.com/store/catalog/Accessories/Kool-Kaddy-12V-Cooler/ID=prod1833617navCount=0navAction=push-product http://www.walgreens.com/store/catalog/Accessories/Kool-Kaddy-12V-Cooler/ID=prod1833617navCount=0navAction=push-product located using search term: cooler using the search term thermoelectric is even better Bruce Richard W. Solomon wrote: Can you be a little more specific about the cooler ? Walgreens search function is rather laborious and clumsy. Tnx, Dick, W1KSZ -Original Message- From: J. Forsterj...@quik.com Sent: Dec 24, 2009 6:58 PM To: Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: Re: [time-nuts] Cheap Rubidium (heatpipe cooling for) That's why I've been suggesting active control with TE devices. You can buy a small TE cooler at Walgreens for about $20. It's big enough for a 6-pack of Coke cans and already comes in an insulated box. Add a simple temperature control in series w/ the DC supply and you should be well on the way. -John = Hi The original intent was to simply take an existing cheap rubidium and do simple things to it. Tearing it into pieces and redesigning parts of it was not anything I originally contemplated. The tight integration of the physics package to the electronics would make this a fairly involved process. Bob On Dec 24, 2009, at 5:42 PM, Magnus Danielson wrote: Hal Murray wrote: A heat pipe might work if the fluid had a sufficiently low boiling point. The rubidium isn't terribly tolerant of high temperatures, and I'm going to pick up some heat rise as I put it inside some baffles / shields. You need to find something that fits a fairly narrow window. This is all backwards. The main reason the typical Rubidium box needs a serious heat sink is that there is an active heater inside it heating up the lamp to get it up to operating temperature. That part of the system better be tolerant of high (enough) temperature. ... or a less heat-producing alternative could be used. The Rubidium-lamp produces two wavelengths of which one is filtered by a Rubidium-filter which leaves the final pumping wavelength. This is what a laser diode could supply instead. Maybe things would be a lot better/simpler if the heating/cooling we have been discussing were split into two sections. One for the lamp assembly, and a second for the electronics. Most of the discussion has been on thermal isolation of the entier units. Not what needs generates temperature and what requires temperature stability etc. Anybody know what the thermal coefficient of the lamp is relative to the electronics? I am not sure I know what you mean by this... 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. ___ 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. ___ 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] Reminder -- MVUS Frequency Measuring Test begins 1500 UTC Monday
We're all set for the FMT beginning at 1500 UTC tomorrow. A couple of minor changes from the earlier announcement: * The 80M frequency will be around 3583 kHz, not 3577. * The 2M frequency (within 50 Hz) will be 144.2743 MHz. * We'll have a little more power on HF than we thought -- about 15 watts, rather than 5. John Original Message The Midwest VHF/UHF Society (MVUS, located in Southwest Ohio) is pleased to announce that the third MVUS Frequency Measuring Test will be held on December 28-30, 2009. The MVUS Frequency Measuring Test is intended to supplement, not replace, the ARRL FMT. The test will use a novel format. Instead of the usual 5 to 15 minute test, we will transmit simultaneously and continuously on 80, 40, and 20 meters for 48 hours. We hope this long transmission period, which will encompass two full propagation days, will encourage new techniques and experiments. For example, it should be possible to measure Doppler shift caused by ionospheric raising and lowering. The test will begin with a call-up starting at about 1445 UTC (0945 EST) on 28 December. The continuous transmission period will begin at 1500 UTC (1000 EST) on Monday, December 28) and will end at 1500 UTC (1000 EST) on Wednesday, December 30. The signal will be a continuous carrier with CW ID every ten minutes. Transmissions will be from W8KSE in Dayton, Ohio (grid square EM79). Here are more details: Start time 1500 UTC (1000 EST) Monday, December 28, 2009. Nominal frequencies: 3577, 7055, and 14055 kHz, plus or minus QRM. NOTE: Check here right before the test for last minute frequency changes. Power: about 5 watts. Antenna: Vertical on 80M, inverted vee on 40M, and 3 element yagi at about 90 feet, aimed west, on 20 meters, Submit entries by January 15, 2010 using the new, improved submission form at www.febo.com/pages/mvus-fmt/entry_form.html. We hope this FMT will encourage new experiments (and experimenters!) taking advantage of the long transmission duration. Therefore, a prize will be awarded to the most interesting report received, as determined by the MVUS Official Committee on Such Things. We also are planning other performance based prizes, but have not finalized those or the prize categories at this time. We will publish the official frequencies to time-nuts and fmt-nuts shortly after the submission deadline , and will make the full results available on the MVUS FMT web page as soon as we can. Our goal is to transmit a signal known in frequency to parts in 10e-12 (i.e., less than 0.0001 Hz error at 10 MHz) and stable to a similar level during the course of the transmission, as they will be derived from an on-site Cesium-based reference. Frequencies will be measured at the transmitter site with a system capable of microHertz resolution referenced to a GPS disciplined oscillator, and will also be monitored by another station in groundwave range that can measure the frequencies with similar accuracy. Further information will be posted at http://www.febo.com/time-freq/mvus-fmt. For discussion about off-air frequency measurement, we suggest you check out the FMT-nuts mailing list, sponsored by Connie Marshall, K5CM. For details, go to http://tech.groups.yahoo.com/group/FMT-nuts. If you have any questions, please send them to f...@mvus.org. Looking forward to a fun event! ___ 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] Timenoob - Cheap and simple 10MHz reference
Hi all, just subscribed, I would like a quick advice on a 10MHz reference for calibrating my instruments and for fun. In particular, I would like to know if you could give me advice on EFRATOM FRS-A,FRS-C, DATUM LPRO-101, Thunderbolt and such. I would prefer a GPSDO (like the Thunderbolt), but budget is very tight (about 100EUR), so I am searching old surplus stuff on Ebay. Some examples: http://cgi.ebay.com/Thunderbolt-PRECISION-GPS-10mhz-FREQUENCY-TIME-Standard_W0QQitemZ270504461779QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d3 http://cgi.ebay.com/EFRATOM-10MHZ-LPRO-101-Rubidium-Frequency-Standard_W0QQitemZ270504461780QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d4 Any caveat, anything I should ask to the seller? Minimal fw version for the Thunderbolt (2.2 is okay)? Thanks in advance, Giuseppe PS: I am in Italy ___ 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] Timenoob - Cheap and simple 10MHz reference
Hi Your budget is going to make things tough. A Thunderbolt needs a triple supply (+12, -12, and +5) to operate. It also needs a GPS antenna of some sort. The Rubidiums all need a supply and a heat sink. Some of them like the FRS-A need unusual connectors. They all need to be operated continuously to get the best accuracy. That makes powering them with a shared lab supply impractical. The Thunderbolt is accurate as a stand alone device because it uses GPS. The rubidiums are all fairly accurate by design, but they would need to be calibrated against something else to be as accurate as the Thunderbolt. Simple look at it: If you need ~ 3x10-9 accuracy, then the rubidiums are all fine. If you need 2 x10-10 accuracy, then the Thunderbolt is your only choice. In between those two limits, it depends on a lot of details like how long between calibrations, environment (like temperature), and sources of calibration. Even at the limits I've mentioned, what you are calibrating might impact the choice. If you have a spare triple output supply already, Then the Thunderbolt is inside your budget. If you do not have a supply, you probably can pick up the pieces on individual auctions with some luck and patience. If you go with a rubidium, look for a dealer who will include the connectors for the device. One last point: The Thunderbolt *probably* will run for a very long time. The rubidiums may also run for a long time, or they may die 5 or 10 years from now due to lamp wear out. Lots to think about. Bob On Dec 27, 2009, at 4:12 PM, Giuseppe Marullo wrote: Hi all, just subscribed, I would like a quick advice on a 10MHz reference for calibrating my instruments and for fun. In particular, I would like to know if you could give me advice on EFRATOM FRS-A,FRS-C, DATUM LPRO-101, Thunderbolt and such. I would prefer a GPSDO (like the Thunderbolt), but budget is very tight (about 100EUR), so I am searching old surplus stuff on Ebay. Some examples: http://cgi.ebay.com/Thunderbolt-PRECISION-GPS-10mhz-FREQUENCY-TIME-Standard_W0QQitemZ270504461779QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d3 http://cgi.ebay.com/EFRATOM-10MHZ-LPRO-101-Rubidium-Frequency-Standard_W0QQitemZ270504461780QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d4 Any caveat, anything I should ask to the seller? Minimal fw version for the Thunderbolt (2.2 is okay)? Thanks in advance, Giuseppe PS: I am in Italy ___ 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] Timenoob - Cheap and simple 10MHz reference
And started down the dark path you have. You will not have to wait long before you completely succumb to the dark side. Jim Palfreyman 2009/12/28 Bob Camp li...@cq.nu: Hi Your budget is going to make things tough. A Thunderbolt needs a triple supply (+12, -12, and +5) to operate. It also needs a GPS antenna of some sort. The Rubidiums all need a supply and a heat sink. Some of them like the FRS-A need unusual connectors. They all need to be operated continuously to get the best accuracy. That makes powering them with a shared lab supply impractical. The Thunderbolt is accurate as a stand alone device because it uses GPS. The rubidiums are all fairly accurate by design, but they would need to be calibrated against something else to be as accurate as the Thunderbolt. Simple look at it: If you need ~ 3x10-9 accuracy, then the rubidiums are all fine. If you need 2 x10-10 accuracy, then the Thunderbolt is your only choice. In between those two limits, it depends on a lot of details like how long between calibrations, environment (like temperature), and sources of calibration. Even at the limits I've mentioned, what you are calibrating might impact the choice. If you have a spare triple output supply already, Then the Thunderbolt is inside your budget. If you do not have a supply, you probably can pick up the pieces on individual auctions with some luck and patience. If you go with a rubidium, look for a dealer who will include the connectors for the device. One last point: The Thunderbolt *probably* will run for a very long time. The rubidiums may also run for a long time, or they may die 5 or 10 years from now due to lamp wear out. Lots to think about. Bob On Dec 27, 2009, at 4:12 PM, Giuseppe Marullo wrote: Hi all, just subscribed, I would like a quick advice on a 10MHz reference for calibrating my instruments and for fun. In particular, I would like to know if you could give me advice on EFRATOM FRS-A,FRS-C, DATUM LPRO-101, Thunderbolt and such. I would prefer a GPSDO (like the Thunderbolt), but budget is very tight (about 100EUR), so I am searching old surplus stuff on Ebay. Some examples: http://cgi.ebay.com/Thunderbolt-PRECISION-GPS-10mhz-FREQUENCY-TIME-Standard_W0QQitemZ270504461779QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d3 http://cgi.ebay.com/EFRATOM-10MHZ-LPRO-101-Rubidium-Frequency-Standard_W0QQitemZ270504461780QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d4 Any caveat, anything I should ask to the seller? Minimal fw version for the Thunderbolt (2.2 is okay)? Thanks in advance, Giuseppe PS: I am in Italy ___ 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] chip scale atomic clock
On Dec 26, 2009, at 10:36 AM, Robert Lutwak wrote: I pay pretty close attention to what people in this field are saying, and I've never heard anyone say we'll get to 1e-11 short term stability at 1 second real soon now. 1e-11 at 1 second is the XPRO spec (and 2X better than LPRO or PRS10). There are good (physics) reasons why those units all draw 100X more power than a CSAC. CSAC is intended for portable battery-powered operation. Surely your basement has the space and wallplug power to support an LPRO. (p.s. don't cool the damn thing, heat it). The cats were much happier during the CsIII development (see http:// home.comcast.net/~rlutwak). It was bigger and warmer. Any Cat-Nuts out there who can help me find one with significantly lower SWAP? You know, that gives me an idea...I could justify some interesting equipment if I assured the XYL that it was simply a cat bed heater. As for this heat sinking of a Rb, might it be better to use a refrigerator? More practical. Tom Frank, KA2CDK ___ 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] Notes on the Driscoll VHF Overtone Crystal Oscillator
Interesting read on a low phase noise oscillator by Chris Bartram GW4DGU http://www.christopherbartramrfdesign.com/blaenffos/oscillator/VLNO.pdf ___ 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] Timenoob - Cheap and simple 10MHz reference
Thanks a lot to all for your quick answer. Rubinium should be good for my needs, but buying it surplus makes me think I could get something very used (and abused) and it does not have the self correcting thing thunderbolt has. GPSDO gives me also the time, maybe with a supercool LCD display. A Thunderbolt needs a triple supply (+12, -12, and +5) to operate. It also needs a GPS antenna of some sort. Do you know exactly the power requirement? On Ebay I read 15W then few mA on each branch (board only). Something is not clear to me. The dark side of the noon already embraced I have Giuseppe PS: I am experiencing mail problems for the first time in many years, please anyone willing to contact me directly do cc copy also this other email address: giuseppe.maru...@iname.com while my ISP gathers back all the bits they lost (2 days of emails vanished from my IMAP account under my eyes, literally) ___ 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] Notes on the Driscoll VHF Overtone Crystal Oscillator
Tom Clifton wrote: Interesting read on a low phase noise oscillator by Chris Bartram GW4DGU http://www.christopherbartramrfdesign.com/blaenffos/oscillator/VLNO.pdf There are several VHF crystal Oscillators designed by M Driscoll. The one shown is merely derived from one variant. It has an unecessary constraint on setting the crystal current. Much better results are obtained by implementing the diode clamp as a capacitively coupled peak to peak detector the output of which is connected to a low noise dc source. The crystal current can then be adjusted by varying the dc source voltage. 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] Timenoob - Cheap and simple 10MHz reference
giuse...@marullo.it said: Do you know exactly the power requirement? On Ebay I read 15W then few mA on each branch (board only). Something is not clear to me. http://www.leapsecond.com/pages/tbolt/power.htm Lots more Thunderbolt info here: http://www.leapsecond.com/pages/tapr-tbolt/ -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] Timenoob - Cheap and simple 10MHz reference
Hi Giuseppe, I think you would be better served with the Thunderbolt as it is both a GPS and an oscillator, that is it is a GPSDO. Last I remember, an eBay user Flukel (the last character is a lower case L) was spoken of, on this list, as being a reliable Chinese vendor. He had oscillators, Rubidiums and Thunderbolts. That said, a power supply is easy to construct from many other dead chasis parts and if needed the regulator chips are pretty cheap (well here in the USA anyway). If you do go that way and have trouble scrounging some parts for the power suppply, perhaps some of us here can help with that. BillWB6BNQ Giuseppe Marullo wrote: Thanks a lot to all for your quick answer. Rubinium should be good for my needs, but buying it surplus makes me think I could get something very used (and abused) and it does not have the self correcting thing thunderbolt has. GPSDO gives me also the time, maybe with a supercool LCD display. A Thunderbolt needs a triple supply (+12, -12, and +5) to operate. It also needs a GPS antenna of some sort. Do you know exactly the power requirement? On Ebay I read 15W then few mA on each branch (board only). Something is not clear to me. The dark side of the noon already embraced I have Giuseppe PS: I am experiencing mail problems for the first time in many years, please anyone willing to contact me directly do cc copy also this other email address: giuseppe.maru...@iname.com while my ISP gathers back all the bits they lost (2 days of emails vanished from my IMAP account under my eyes, literally) ___ 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] Notes on the Driscoll VHF Overtone Crystal Oscillator
Hi The feedback network in the Fig 7 schematic makes a lot more sense than the network in the first Fig 7 Bob On Dec 27, 2009, at 7:19 PM, Tom Clifton wrote: Interesting read on a low phase noise oscillator by Chris Bartram GW4DGU http://www.christopherbartramrfdesign.com/blaenffos/oscillator/VLNO.pdf ___ 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] Timenoob - Cheap and simple 10MHz reference
Hi The simple answer on the supply is that there are a couple of answers. Very little current is pulled from the -12 supply. I can not imagine a supply that would not keep up with the -12 requirement. The +12 supply mainly runs the OCXO in the unit. Since it's running an oven, the power will drop off after warmup. It will also be lower at higher temperatures. Depending on exactly which OCXO you get in your unit, the power may be a little higher or a little lower. A 5V supply that can furnish 300 ma should be adequate. All of the supplies needed *could* be pulled off of a typical desk top PC power supply. If you do go that way, be sure to put some simple RF filtering in the supply leads. The unit it's self has a fairly basic case. Enclosing even in a simple pine box should improve it's performance. It would also protect the leads from getting damaged in use. The enclosure does not need to be elaborate. You should be able to make it for free from scrap materials. I have bought Thunderbolts from several dealers on eBay over the last month. All of them seem to be supplying the same product (same date codes, and firmware). They all seem to be from 2003 or 2004. Some dealers ship faster than others, some include a HF power splitter, some include a power connector. I have not had any of the units on power long enough to know if some are actually better than others. Good Luck! Bob On Dec 27, 2009, at 7:56 PM, Giuseppe Marullo wrote: Thanks a lot to all for your quick answer. Rubinium should be good for my needs, but buying it surplus makes me think I could get something very used (and abused) and it does not have the self correcting thing thunderbolt has. GPSDO gives me also the time, maybe with a supercool LCD display. A Thunderbolt needs a triple supply (+12, -12, and +5) to operate. It also needs a GPS antenna of some sort. Do you know exactly the power requirement? On Ebay I read 15W then few mA on each branch (board only). Something is not clear to me. The dark side of the noon already embraced I have Giuseppe PS: I am experiencing mail problems for the first time in many years, please anyone willing to contact me directly do cc copy also this other email address: giuseppe.maru...@iname.com while my ISP gathers back all the bits they lost (2 days of emails vanished from my IMAP account under my eyes, literally) ___ 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] Notes on the Driscoll VHF Overtone Crystal Oscillator
An inductor in series with the 220 ohm emitter resistor will improve the phase noise floor. The MMIC output amplifier has a wider bandwidth than necessary and doesn't have a particularly high reverse isolation. One could improve this by substituting a CB cascade or other discrete amplifier cascade. Alternative methods of extracting the signal from the collector of the second transistor may be more effective in maintaining a low phase nose floor. Bruce Bob Camp wrote: Hi The feedback network in the Fig 7 schematic makes a lot more sense than the network in the first Fig 7 Bob On Dec 27, 2009, at 7:19 PM, Tom Clifton wrote: Interesting read on a low phase noise oscillator by Chris Bartram GW4DGU http://www.christopherbartramrfdesign.com/blaenffos/oscillator/VLNO.pdf ___ 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.
