Re: [time-nuts] 510 doubler and old Toko RF catalogue (Cirkit 2nd ed.1994)
Hi Andrea I have here a Cirkit 2nd edition Toko catalogue dated 1993 (a firm local to me I dealt with quite a lot) The cat is in good condition but it is 128 pages and a glued spine so scanning risks breaking it up. However the 10k range occupies just one page and if the part adjacent to the spine does not copy well all you will lose is the 100off price column (and I dont think you can buy them for that now 20 years on :-)) ) Give me a little time and I will do you a scan of the page, and mail it direct as a PDF. I might actually have some new Toko coils in the component drawers but they may not be 10K. However I also have a lot of 5MHz OCXOs including Racal an Toyocom so I might have something useful if you dont find a source nearer to you. Best Wishes Alan G3NYK - Original Message - From: Andrea Baldoni erm1ea...@ermione.com To: time-nuts@febo.com Sent: Tuesday, January 27, 2015 3:53 PM Subject: [time-nuts] 510 doubler and old Toko RF catalogue (Cirkit 2nd ed.1994) Hello All. Now I have some 5MHz DOCXO. I have started to experiment with them and I would like to build a frequency doubler. I already saw the very nice circuit from Gerhard Hoffmann for the Lucent, I saw some diode circuits from Wenzel (my oscillators output around 1.5Vpp loaded, too scarce for diodes alone; I used a 1:2 transformer just to try and I obtained the 10MHz but not good for anything) and I saw the doubler circuit Racal Dana used in some counters I attached. I would like to build something like one of those; it's a full wave rectifier made by a differential amplifier and two diodes, followed by a 10MHz amp/filter chain much like the IF of FM radios (with AGC too!). I don't know if it's adequate for serious use; I also saw the Z3811-80007 doubler board used in Z3815A and Z3805A according to the seller, much more modern and surely better, but I have not its schematic. Someone knows it? I have bought one of the Racal units, just to have the opportunity to fiddle with an already working one; I identified the IF transformers used there and are Toko common 10.7MHz Q=80 unit. They are not built anymore but it's possible to find similar ones in Internet; however it happens to me frequently to need information about the old Toko 10K series and there is not any comprehensive source. I saw I share this frustration with many people in the electronics newsgroups. Finally I found that a (fairly) complete Toko catalog existed, it was sold by Cirkit in '94 and it's not available anymore. Someone has it in PDF form, or want to borrow it to me to scan it? By the way, I see that really many of the 10MHz reference out there, are in effect doubled 5MHz ones so build a doubler seems reasonable for me. Best regards, Andrea Baldoni ___ 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] 510 doubler
Andrea wrote: Now I have some 5MHz DOCXO. I have started to experiment with them and I would like to build a frequency doubler. * * * By the way, I see that really many of the 10MHz reference out there, are in effect doubled 5MHz ones so build a doubler seems reasonable for me. One thing to watch for is the 5MHz leakage component. If you are going to use the 10MHz standard for time-nuts experiments, the 5MHz component needs to be WAY down ( -80dBc) or you will get funny periodic ripples in stability plots. Despite having two 5MHz traps, one recently published design suppresses the 5MHz component only about 52dB below the 10MHz output, and the 20MHz and 30MHz components are also only -50 to -55dB. For this reason (and some others, see discussions over the last several months in the archives) I prefer a doubler built with a quadrature hybrid coupler and a balanced mixer. There is a write-up here: http://www.ko4bb.com/manuals/download.php?file=02_GPS_Timing/4_App_Notes_and_Articles/Frequency_doubler_quadrature_DBM.pdf I recently revived an old, stalled project to develop a JFET push-push doubler for use at 5MHz (see schematic below). FETs with very high transconductance and very small pinchoff voltage (what a tube designer would call a sharp cutoff characteristic) (e.g., 2SK369, BF862, etc.) are attractive on first look because they can operate with lower conversion loss or even some conversion gain. However, they are not well suited for doubler duty for two reasons: (i) their characteristics have a very short range of 2nd-order curvature, so in order to keep noise down they must be driven into regions of higher-order distortion and therefore generate lots of spurious energy; and (ii) they are devilishly hard to match well enough to suppress the input frequency feedthrough. Note that you also need to put enough voltage on the FET drains to get them well into the saturation region -- a Vcc of 5v is not enough. Again, the penalty is lots of spurious energy. So, the lower conversion loss of sharp-cutoff FETs is not the benefit it might at first appear to be -- it is much easier to add gain after the doubler than to remove unwanted spurious mixing products. The design below uses medium-cutoff FETs and a Vcc of 15v (I found that J111 and J310 work best and can be matched sufficiently with a one-point match; 2N4416 and others also work, but are fussier and would benefit from a 2- or 3-point match). At an input of 500mVrms, their long 2nd-order characteristic is used efficiently to generate 10MHz with relatively little spurious energy. I had no problem finding one or more FET pairs matched to within 1mV, given 20 devices from the same lot (YMMV). With properly adjusted traps at 5, 20, and 30MHz, all spurious responses were below -80dBc. The inductors can be commercial RF parts with Q of 200 or so (I used some high-quality through-hole RF inductors I had on hand -- I doubt any SMD inductors will work). The trap capacitors should be C0G/NP0 ceramics for the bulk of the capacitance, plus very small trimmers (I used 27pF, 27pF, and 100pF plus 0.2--6pF glass piston trimmers). I wound the two transformers on Mix-61 toroid cores (each winding is 20 turns on a FT37-61 core -- the inductance is a little lower than called out). Mini-Circuits parts (or equivalents) may also work. Best regards, Charles ___ 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] SR620 question
Hi, fellow time nuts, I have some questions regarding the Stanford SR620: 1. Is it a drawback wrt ADEV when a SR620 does not have have the opt. oven if I have an ultra clean external reference? Does it use the external ref directly or does it just pull the own reference to the external value in the long run, no matter if it's the good or the bad oscilator? 2 I have seen that the manual has a parts list and references the circuit diagrams, but they are not included in the pdf. Are the circuits somewhere out there? My 5370A has become so unreliable that it needs replacement. regards, Gerhard ___ 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] 510 doubler
Using the square law characteristic will inevitably increase the phase noise floor particularly in the flicker region with respect to just using the switching characteristic of a JFET, diode or BJT (non saturated).The only viable solution is to use better filtering of the output of a switching multiplier.If you intend to use a diode ring based mixer configuration diode connected (collector shorted to base) npns such as 2N222's are significantly quieter (as shown by NIST) than schottky diodes for frequencies below 40MHz or so. Bruce. On Wednesday, 28 January 2015 8:25 AM, Charles Steinmetz csteinm...@yandex.com wrote: Andrea wrote: Now I have some 5MHz DOCXO. I have started to experiment with them and I would like to build a frequency doubler. * * * By the way, I see that really many of the 10MHz reference out there, are in effect doubled 5MHz ones so build a doubler seems reasonable for me. One thing to watch for is the 5MHz leakage component. If you are going to use the 10MHz standard for time-nuts experiments, the 5MHz component needs to be WAY down ( -80dBc) or you will get funny periodic ripples in stability plots. Despite having two 5MHz traps, one recently published design suppresses the 5MHz component only about 52dB below the 10MHz output, and the 20MHz and 30MHz components are also only -50 to -55dB. For this reason (and some others, see discussions over the last several months in the archives) I prefer a doubler built with a quadrature hybrid coupler and a balanced mixer. There is a write-up here: http://www.ko4bb.com/manuals/download.php?file=02_GPS_Timing/4_App_Notes_and_Articles/Frequency_doubler_quadrature_DBM.pdf I recently revived an old, stalled project to develop a JFET push-push doubler for use at 5MHz (see schematic below). FETs with very high transconductance and very small pinchoff voltage (what a tube designer would call a sharp cutoff characteristic) (e.g., 2SK369, BF862, etc.) are attractive on first look because they can operate with lower conversion loss or even some conversion gain. However, they are not well suited for doubler duty for two reasons: (i) their characteristics have a very short range of 2nd-order curvature, so in order to keep noise down they must be driven into regions of higher-order distortion and therefore generate lots of spurious energy; and (ii) they are devilishly hard to match well enough to suppress the input frequency feedthrough. Note that you also need to put enough voltage on the FET drains to get them well into the saturation region -- a Vcc of 5v is not enough. Again, the penalty is lots of spurious energy. So, the lower conversion loss of sharp-cutoff FETs is not the benefit it might at first appear to be -- it is much easier to add gain after the doubler than to remove unwanted spurious mixing products. The design below uses medium-cutoff FETs and a Vcc of 15v (I found that J111 and J310 work best and can be matched sufficiently with a one-point match; 2N4416 and others also work, but are fussier and would benefit from a 2- or 3-point match). At an input of 500mVrms, their long 2nd-order characteristic is used efficiently to generate 10MHz with relatively little spurious energy. I had no problem finding one or more FET pairs matched to within 1mV, given 20 devices from the same lot (YMMV). With properly adjusted traps at 5, 20, and 30MHz, all spurious responses were below -80dBc. The inductors can be commercial RF parts with Q of 200 or so (I used some high-quality through-hole RF inductors I had on hand -- I doubt any SMD inductors will work). The trap capacitors should be C0G/NP0 ceramics for the bulk of the capacitance, plus very small trimmers (I used 27pF, 27pF, and 100pF plus 0.2--6pF glass piston trimmers). I wound the two transformers on Mix-61 toroid cores (each winding is 20 turns on a FT37-61 core -- the inductance is a little lower than called out). Mini-Circuits parts (or equivalents) may also work. Best regards, Charles ___ 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] Unique TBolt GPS characteristics
Every GPS receiver calculates its clock offset (phase error, in time-nut terms) as part of its four-dimensional position fix. It can apply almost the same math to calculate its clock rate (frequency error) as part of a four-dimensional velocity fix. In position hold mode, the Thunderbolt calculates its timing errors (both phase and frequency) using similar one-dimensional algorithms. The accuracy of these measurements is determined by all the factors that affect GPS, but the precision (resolution) of these measurements is effectively infinite, limited only by IEEE double-precision floating-point math. Almost every other GPSDO uses a hardware time-to-digital converter (TDC, interpolator, etc) to compare the OCXO timebase to the PPS output of a separate GPS receiver. The PPS/TDC scheme has four disadvantages relative to the Trimble scheme: A) The resolution of the phase error measurement is limited by the TDC hardware. For example, the HP Z38xx units appear to have 10ns resolution. B) The accuracy of the phase error measurement may be degraded by analog effects in the PPS connection. C) The phase error measurement must be compensated by a software sawtooth correction for best accuracy, because the PPS output is quantized by the receiver clock. D) Frequency error cannot be measured directly, but must be derived from successive phase measurements. The derivative process introduces noise, so the derived frequency error must be heavily filtered. Unfortunately, the Trimble scheme is only available to GPSDO builders who have access to the internal architecture of their GPS receiver. Historically, among the major players, only Trimble and perhaps Zyfer did. Even mighty HP did not. Fortunately, SwiftNav is now selling a (mostly) open-source GPS receiver. Only the FPGA correlator chip is closed-source, and that can be ignored for timing purposes. One would need to build a VCXO-based synthesizer to create the SwiftNav receiver clock frequency from a good OCXO, add a DAC to control the OCXO, and do some software work to add timing functions to the receiver firmware. Adding WAAS corrections to this hypothetical open-source GPSDO could make it noticeably more accurate than a Thunderbolt. Cheers! --Stu ___ 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] question Alan deviation measured with Timelab and counters
Thanks a lot for your comment Bruce, I need to feel a bit deeper the ins and outs of the methods so I guess I will anyway implement both methods on an evaluation PCB and characterize each method. This will bring to me some actual data to compare. I will share the results of course. The plan is to have an eval PCB with 4 independant 10 MHz squarers, isolation amplifiers, mixers, low pass filters and multistage limiting amplifier. Each block will have input/output connectors so that I can combine any architecture with these blocks. The PCB will receive a low noise PSU as well. Before I start the design if one thinks about something to add in the evaluation, this is very welcome. Stephane On Tue, 27 Jan 2015 03:24:44 + (UTC), Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: The performance of the 2 systems should be comparable provided the similar equivalent noise bandwidths are used.Every 10Mhz edge needs to be timestamped with ps resolution and the resulting phase samples low pass filtered and decimated to achieve this.The 10MSPS picosecond or better resolution time stamping with femtosecond integral linearity will be a bit of a challenge to achieve. Bruce On Tuesday, 27 January 2015 3:26 PM, Stéphane Rey steph@wanadoo.fr wrote: I do understand. Has anyone already compared the performances of squaring the 10 MHz vs squaring the IF ? Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Bob Camp Envoyé : dimanche 25 janvier 2015 19:01 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi The approach in the original NIST paper below was sort of a “best guess” about how to do the limiting and filtering. When the paper was presented, a number of us questioned how that part of the circuit was arrived at. The conversation more or less ended up with “that’s something we can investigate further”. The Collins paper (and Bruce’s work based on it) is a much better way to look at the 10 Hz squaring process. At 10 MHz, that stuff is not needed. Bob On Jan 25, 2015, at 10:44 AM, Stéphane Rey steph@wanadoo.fr wrote: Hi everyone. Many thanks for your very useful comments. I had already seen most of the documents you were pointing but not on the collins and Bruce discussion around the multistage filter. However I've already seen this approach in the document from Allan (http://tf.nist.gov/timefreq/general/pdf/84.pdf) At first I had in mind to square the 10 MHz but this is the aim of the evaluation board to evaluate various architectures. So I will implement several squarers including the Collins Approach both at 10 MHz and 100 Hz and all the blocks will have input and output connectors so that I will be able to test several layouts. I will show you the final design. Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Charles Steinmetz Envoyé : dimanche 25 janvier 2015 08:08 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Stephane wrote: I'm now trying to evaluate various architectures of 2-channels squarers and a DMDT. For that I'm designing a PCB with 4 squarers : simple 74ac04 gate biased at VCC/2, a LT1016 comparator, the transistor based differential amplifier from Winzel and the one from Charles. Note that squaring a 10MHz sine wave and squaring a 10 or 100Hz mixer output are two very different tasks. If you start at baseband, a Collins-style multi-stage limiting amp is a great benefit. That is generally not necessary if you start at 10MHz (or if you do use a Collins-style limiter it needs far fewer stages). All of the squarers you mention work well at 10MHz, but not as well at baseband. The LT1719 is easier to apply and faster than the LT1016. You may want to use that instead of the 1016. The LT1719 and LT1715 datasheets show the simplest possible implementation (see below). The MPSH81 devices in my version are available in surface-mount (MMBTH81) if that is more convenient. Other fast transistors will also work (BFT92, BFT93, BFG31). Best regards, Charles --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. http://www.avast.com ___ 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. --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. http://www.avast.com
[time-nuts] 510 doubler and old Toko RF catalogue (Cirkit 2nd ed. 1994)
Hello All. Now I have some 5MHz DOCXO. I have started to experiment with them and I would like to build a frequency doubler. I already saw the very nice circuit from Gerhard Hoffmann for the Lucent, I saw some diode circuits from Wenzel (my oscillators output around 1.5Vpp loaded, too scarce for diodes alone; I used a 1:2 transformer just to try and I obtained the 10MHz but not good for anything) and I saw the doubler circuit Racal Dana used in some counters I attached. I would like to build something like one of those; it's a full wave rectifier made by a differential amplifier and two diodes, followed by a 10MHz amp/filter chain much like the IF of FM radios (with AGC too!). I don't know if it's adequate for serious use; I also saw the Z3811-80007 doubler board used in Z3815A and Z3805A according to the seller, much more modern and surely better, but I have not its schematic. Someone knows it? I have bought one of the Racal units, just to have the opportunity to fiddle with an already working one; I identified the IF transformers used there and are Toko common 10.7MHz Q=80 unit. They are not built anymore but it's possible to find similar ones in Internet; however it happens to me frequently to need information about the old Toko 10K series and there is not any comprehensive source. I saw I share this frustration with many people in the electronics newsgroups. Finally I found that a (fairly) complete Toko catalog existed, it was sold by Cirkit in '94 and it's not available anymore. Someone has it in PDF form, or want to borrow it to me to scan it? By the way, I see that really many of the 10MHz reference out there, are in effect doubled 5MHz ones so build a doubler seems reasonable for me. Best regards, Andrea Baldoni ___ 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.
