Re: [time-nuts] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] On 7/7/07, Dr Bruce Griffiths [EMAIL PROTECTED] wrote: With suitable modifications to allow individual adjustement/selection of the bias for each JFET a pair of the more readily obtainable J310's can be substituted for the U431. Vishay Siliconix U431 JFET pairs are available in single quantities from www.newark.com for ~$8. ___ 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Hi Bruce, With a quick search of the NIST site, I couldn't find any mention of this, and the circuit diagram in your GIF was a little small and fuzzy: is that a crystal on the centre-tap of the secondary of the first transformer? Would it be tuned to the input or output frequency? And would you know the values of the components? Thanks, Peter The schematic for a NIST developed, low phase noise frequency doubler is attached. This device appears to perform significantly better than the Wenzel FET doubler specifications at least in the flicker noise region. With suitable modifications to allow individual adjustement/selection of the bias for each JFET a pair of the more readily obtainable J310's can be substituted for the U431. 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Peter Vince wrote: Hi Bruce, With a quick search of the NIST site, I couldn't find any mention of this, and the circuit diagram in your GIF was a little small and fuzzy: is that a crystal on the centre-tap of the secondary of the first transformer? Would it be tuned to the input or output frequency? And would you know the values of the components? Thanks, Peter Peter It just an RF bypass capacitor to ground. This circuit was embedded in a very small section of a much larger paper, so its difficult to find. You may even have read the paper and not have noticed the mixer circuit. The resistor from the centre tap to ground is selected so that the peak drain current is around 28mA or so when the RF is applied RF input ~ 13dBm. Input transformer 1:4 turns ratio (or thereabouts) centre tapped secondary. Output transformer 2:1 turns ratio (or thereabouts). RF bypass capacitor depends on input frequency typically 100nF or so. 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] In a message dated 7/9/2007 01:59:46 Pacific Daylight Time, [EMAIL PROTECTED] writes: It just an RF bypass capacitor to ground. This circuit was embedded in a very small section of a much larger paper, so its difficult to find. You may even have read the paper and not have noticed the mixer circuit. The resistor from the centre tap to ground is selected so that the peak drain current is around 28mA or so when the RF is applied RF input ~ 13dBm. Input transformer 1:4 turns ratio (or thereabouts) centre tapped secondary. Output transformer 2:1 turns ratio (or thereabouts). RF bypass capacitor depends on input frequency typically 100nF or so. Bruce Hi Bruce, nice circuit. Many questions: I wonder how well it works to get a 5MHz source up to 10MHz? Also, would you have recommendations on the transformer part numbers? (MiniCircuits, MaCom, etc)? I think the transformers are probably key to getting good phase noise (preventing them from saturating, crosstalk, etc). Do you have a suggestion on who makes the best (lowest-noise) JFets? Where could we find the original paper's PDF? Lastly, how much fundamental attenuation would you expect from such a circuit? Thanks! Said ** See what's free at http://www.aol.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.
Re: [time-nuts] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Where does one find this circuit ? Thanks, Dick, W1KSZ [EMAIL PROTECTED] wrote: In a message dated 7/9/2007 01:59:46 Pacific Daylight Time, [EMAIL PROTECTED] writes: It just an RF bypass capacitor to ground. This circuit was embedded in a very small section of a much larger paper, so its difficult to find. You may even have read the paper and not have noticed the mixer circuit. The resistor from the centre tap to ground is selected so that the peak drain current is around 28mA or so when the RF is applied RF input ~ 13dBm. Input transformer 1:4 turns ratio (or thereabouts) centre tapped secondary. Output transformer 2:1 turns ratio (or thereabouts). RF bypass capacitor depends on input frequency typically 100nF or so. Bruce Hi Bruce, nice circuit. Many questions: I wonder how well it works to get a 5MHz source up to 10MHz? Also, would you have recommendations on the transformer part numbers? (MiniCircuits, MaCom, etc)? I think the transformers are probably key to getting good phase noise (preventing them from saturating, crosstalk, etc). Do you have a suggestion on who makes the best (lowest-noise) JFets? Where could we find the original paper's PDF? Lastly, how much fundamental attenuation would you expect from such a circuit? Thanks! Said ** See what's free at http://www.aol.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. -- 73, Dick, W1KSZ ___ 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] From: Dick, W1KSZ [EMAIL PROTECTED] Subject: Re: [time-nuts] NIST frequency doubler Date: Mon, 09 Jul 2007 19:42:23 -0400 Message-ID: [EMAIL PROTECTED] ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Where does one find this circuit ? http://tf.nist.gov/general/pdf/977.pdf and referenced is this paper: http://tf.nist.gov/timefreq/general/pdf/891.pdf http://feltondesign.com/slpnfed.pdf 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Hi Bruce, nice circuit. Many questions: I wonder how well it works to get a 5MHz source up to 10MHz? Also, would you have recommendations on the transformer part numbers? (MiniCircuits, MaCom, etc)? I think the transformers are probably key to getting good phase noise (preventing them from saturating, crosstalk, etc). Do you have a suggestion on who makes the best (lowest-noise) JFets? Where could we find the original paper's PDF? Lastly, how much fundamental attenuation would you expect from such a circuit? Thanks! Said Said Embedded in: 1992 IEEE FREQUENCY CONTROL SYMPOSIUM ULTRA-HIGH STABILITY SYNTHESIZER FOR DIODE LASER PUMPED RUBIDIUM John P. Lowe, F. L. Walls, and R. E. Drullinger Time and Frequency Division National Institute of Standards and Technology 325 Broadway Boulder, CO 80303 There is little more than the image I extracted. This circuit had been developed somewhat earlier and as far as I have been able to tell hasn't appeared anywhere else. It has also been used for a 5MHz to 10MHz doubler. (Wenzels 5- 20MHz JFET doublers are supposed to be derivatives of a NIST design) There is no fundamental reason that it cant be used at even lower frequencies, provided suitable transformers can be built/obtained. The real question is perhaps who make JFETS (especially matched ones) anymore. JFET matched pairs: Interfet http://www.interfet.com/ Linear systems http://www.linearsystems.com Other JFETs: Vishay/Siliconix http://www.vishay.com/fets-small-signal/SSFsgnchjampP/ Onsemiconductor: http://www.onsemi.com/PowerSolutions/parametrics.do?id=806 Fairchild semiconductor http://www.fairchildsemi.com/sitesearch/fsc.jsp?command=eqattr1=AAAFamilyattr2=Junction+FET+%28JFET%29 http://www.fairchildsemi.com/sitesearch/fsc.jsp?command=eqattr1=AAAFamilyattr2=Junction+FET+%28JFET%29 Various other suppliers Hitachi Sony etc. Noise specifications are similar for all manufacturers, however to achieve the stated phase noise performance testing and selection of JFETS may be required. At lower frequencies higher capacitance JFETS should be usable. a pair of J310s can be substituted for the U431 but some matching of the JFETS is desirable The fundamental attenuation depends on the matching of the 2 FETs and the input transformer. I would expect 20dB suppression of the fundamental to be easy and perhaps 40dB if the circuit is modified slightly to allow compensation for residual JFET mismatch. Transformers: There should not be any great problem with input transformer saturation as the dc current flowing in the secondary due to FET mismatch will be small. The output transformer has dc current flowing in the primary (~20mA for 28mA peak JFET currents) this doesn't appear to exceed the specified limits for most Minicircuits transformers, however these limits aren't well specified in the datasheets (it does make a difference if it is flowing in the secondary or primary of a transformer with a turns ratio of other than 1:1, Minicircuits do not specify which winding the dc limit refers to). NIST regularly drive the primary of Minicircuits 2:1 stepdown (200:50 ohm) transformers without difficulties due to transformer saturation. The best turns ratio for the input transformer is best determined by a combination of simulation and testing to achieve the desired JFET peak drain currents. 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] In a message dated 7/9/2007 17:20:56 Pacific Daylight Time, [EMAIL PROTECTED] writes: The best turns ratio for the input transformer is best determined by a combination of simulation and testing to achieve the desired JFET peak drain currents. Bruce Thanks for the info Bruce, Magnus, I will be reading the Felton paper to get more info. With a bit of trickery, I bet this circuit can be used with Bipolar transistors. bye, Said ** See what's free at http://www.aol.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.
Re: [time-nuts] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] In a message dated 7/9/2007 18:34:30 Pacific Daylight Time, [EMAIL PROTECTED] writes: Since JFETS have a relatively large spread in characteristics individual adjustments are required. Bruce Thanks again Bruce, I am not a big fan of Jfets... Prefer Mosfets or Bipolars.. There are some ultra-low-noise Audio Jfets such as the dual LSK389: _http://www.linearsystems.com/products.html#GlossD_ (http://www.linearsystems.com/products.html#GlossD) I wonder if these work well at 5/10MHz... bye, Said ** See what's free at http://www.aol.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.
Re: [time-nuts] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Said To give some idea of the transformer ratios required a simulation using pSpice shows that: When using 2 x 2N4393's connected in parallel (limited choice of JFETs available) for each JFET in the NIST circuit, an input transformer with a 1:2 turns ratio with centre-tapped secondary and an output with a 2:1 turns ratio is about optimum. Input is fed from a 5MHz 2Vrms source with a 50 ohm source impedance (develops 1V rms in a 50 ohm load) source resistor is 100 ohms. Input transformer primary magnetising inductance was 50uH. Output transformer secondary magnetising inductance was 50uH. Output is 1V rms into a 50 ohm load. Output transformer primary dc current is ~ 20mA. To allow adjustment for individual FET characteristics the input transformer secondary centre tap can be grounded and a capacitively bypassed resistor connected in series with the source of each JFET. The resistor values are then selected/adjusted to achieve the desired output and minimise the fundamental component in the output. Trimpots can be used, initially adjust the trimpots to the required value whilst the specified input is applied, then measure each trimpot's resistance setting and replace it with a fixed resistor. Since JFETS have a relatively large spread in characteristics individual adjustments are required. 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] NIST frequency doubler
[EMAIL PROTECTED] wrote Thanks for the info Bruce, Magnus, I will be reading the Felton paper to get more info. With a bit of trickery, I bet this circuit can be used with Bipolar transistors. bye, Said Said You mean like the circuit in the attached file? Input transformer configuration is the only way I can simulate a centre-tapped transformer. 1 ohm resistors are merely present to keep the simulator happy with transformer primaries connected in parallel. The circuit is far more predictable than the JFET version, however there is no data on the close in phase noise performance. Whilst this circuit will work with the 2N3904's shown, with higher ft transistors the emitter base reverse voltage ratings may be exceeded. At least with JFETS the gate source reverse breakdown voltage is relatively high. Bruce BJTCommonBaseFrequencyDoubler.pdf Description: Adobe PDF document ___ 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: ); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] In a message dated 7/9/2007 18:34:30 Pacific Daylight Time, [EMAIL PROTECTED] writes: Since JFETS have a relatively large spread in characteristics individual adjustments are required. Bruce Thanks again Bruce, I am not a big fan of Jfets... Prefer Mosfets or Bipolars.. There are some ultra-low-noise Audio Jfets such as the dual LSK389: _http://www.linearsystems.com/products.html#GlossD_ (http://www.linearsystems.com/products.html#GlossD) I wonder if these work well at 5/10MHz... bye, Said Said Probably not as they tend to have relatively large gate source capacitances especially the lower noise ones. MOSFETS tend to have excessive flicker noise for this application. 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] NIST frequency doubler
The schematic for a NIST developed, low phase noise frequency doubler is attached. This device appears to perform significantly better than the Wenzel FET doubler specifications at least in the flicker noise region. With suitable modifications to allow individual adjustement/selection of the bias for each JFET a pair of the more readily obtainable J310's can be substituted for the U431. Bruce inline: NISTFreqDoubler.gif___ 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Interesting. Diode doublers of this configuration have been around for about 40 years, and of course so have their FET counterparts. While I never did an investigation on any additive residual noise, since typically the 6 dB was enough to mask it, how is this better than the plain jane full wave diode doubler? 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dr Bruce Griffiths Sent: Saturday, July 07, 2007 10:37 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] NIST frequency doubler The schematic for a NIST developed, low phase noise frequency doubler is attached. This device appears to perform significantly better than the Wenzel FET doubler specifications at least in the flicker noise region. With suitable modifications to allow individual adjustement/selection of the bias for each JFET a pair of the more readily obtainable J310's can be substituted for the U431. 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Mike Feher wrote: Interesting. Diode doublers of this configuration have been around for about 40 years, and of course so have their FET counterparts. While I never did an investigation on any additive residual noise, since typically the 6 dB was enough to mask it, how is this better than the plain jane full wave diode doubler? 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 It has lower phase noise especially at lower frequency offsets. About 10-12dB lower (@75Hz offset, 10MHz input) than a typical frequency multiplier according to NIST. 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Well, I guess that is according to NIST. I do not see how an active doubler can have lower noise than a passive one, especially when the original signal has already been degraded by 20log2, or 6 dB so the contribution of the doubler would not even be noticed unless the source was so much better. Regardless, an interesting observation, but I am skeptical. I have seen other stupid measurement procedures come out of these high ranking so called official institutions over the past 40 years. There are a couple I am fighting right now, one regarding measurement of AM/PM conversion and the other basing oscillator long time ageing on short term measurements. Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dr Bruce Griffiths Sent: Saturday, July 07, 2007 11:10 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] NIST frequency doubler Mike Feher wrote: Interesting. Diode doublers of this configuration have been around for about 40 years, and of course so have their FET counterparts. While I never did an investigation on any additive residual noise, since typically the 6 dB was enough to mask it, how is this better than the plain jane full wave diode doubler? 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 It has lower phase noise especially at lower frequency offsets. About 10-12dB lower (@75Hz offset, 10MHz input) than a typical frequency multiplier according to NIST. 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] NIST frequency doubler
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Mike Feher wrote: Well, I guess that is according to NIST. I do not see how an active doubler can have lower noise than a passive one, especially when the original signal has already been degraded by 20log2, or 6 dB so the contribution of the doubler would not even be noticed unless the source was so much better. Regardless, an interesting observation, but I am skeptical. I have seen other stupid measurement procedures come out of these high ranking so called official institutions over the past 40 years. There are a couple I am fighting right now, one regarding measurement of AM/PM conversion and the other basing oscillator long time ageing on short term measurements. Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 However, it apparently makes a detectable (10x) improvement to the short term stability of an atomic frequency standard. Diode frequency doublers do need an amplifier to produce a doubled frequency output at the same level as a JFET frequency doubler. 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.
