Re: [time-nuts] Phase noise measurement (was - no subject)
Bob Camp wrote: Hi If you start with a mixer that runs 500 mV / radian (an RPD-1 at the typical 8 mV / degree + 10%) then -180 below that would be 0.5 nV. Since noise it coherent close in, the DSB to SSB process nets you 1 nV out when you have -180 dbc noise. With a capacitive IF port termination the mixer sensitivity increases somewhat. It increases more when using something like an HP10514 or 10534 than with an RPD-1. Such a termination isnt particularly useful for offsets much above 100kHz or so. If one terminates all mixer ports in 50 ohms as some insist is the best method, then the mixer phase sensitivity is much lower, in which case a somewhat lower noise preamp may be required. The posted plot does show (together with the noise plot for the HPS5.1 preamp) that the 2SK369 and the IF9030 have much lower flicker noise than the BF862. On Aug 22, 2010, at 10:51 AM, Bruce Griffiths wrote: So everything above (and an AD797 and likely an OP-37) will do better than 2 nV / Hz into 1K Hz. That would let you check oscillators in the below -170, but not below -180 range. You might or might not find such an oscillator in your junk box. They certainly do exist. On the plot above, both devices would let you do the same thing at 10 Hz. Now you are into the range of highly unlikely to find. At reasonable frequencies, -135 is doing pretty well at 10 Hz. Bragging rights start at about -140. Highly unlikely cuts in much past that 10 Hz offset. I'm not talking about a one of a kind piece of magic at NIST, but about what's in your junk box. The 2SK369 is still holding ok for -170 at 1 Hz. Even for one of a kind magic, that's pretty crazy. Unlikely to find (and really tough to measure) cuts in at about -120 at 1 Hz. At 0.1 Hz offset, you will need to run an instrument bandwidth below 0.01 Hz to get anything close to a good approximation to the noise. Most lab analyzers run 100X t to get enough data. That puts you out around 10,000 seconds for the run. That's a crazy long time. DC coupled offsets are likely to nuke that run just about every time. I'm by no means knocking the idea of having a good preamp. I'm only trying to point out that the numbers above are *way* past what a reasonable person might need to sort through their basement oscillator collection. 50 db is a lot of margin. Bob For an AC coupled sound card based spectrum analyser dc frequencies much below 2Hz or so are of little interest. Being able to calibrate the preamp + sound card frequency response using the thermal noise of a resistor is convenient. This is more difficult to achieve with a bipolar input stage as the amplifier input current noise is significant. 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] Phase noise measurement (was - no subject)
Hi I've always calibrated my phase noise setups to the phase slope of the mixer I'm using. It does involve switching gains, but it's a direct system calibration. Beat note is 360 degrees, so this chunk is x degrees and you got y mv over that chunk. Check the slope on the other side of the beat note to make sure it's the same. Do some math and you have a radian to volt transfer function. If you are sorting junk box OCXO's it's a pretty good way to do it. The only added steps are an independent measurement of the switched gain / gain flatness and a short circuit input check to estimate the noise floor. Both are an initial setup / one time only sort of thing with most amps. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Tuesday, August 24, 2010 3:25 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Phase noise measurement (was - no subject) Bob Camp wrote: Hi CHOP Being able to calibrate the preamp + sound card frequency response using the thermal noise of a resistor is convenient. This is more difficult to achieve with a bipolar input stage as the amplifier input current noise is significant. 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] Phase noise measurement (was - no subject)
Having a simple method of determining the preamp frequency response can be a useful diagnostic tool during development, particularly if one uses componets like super capacitors in the amplifier signal path. If one doesnt have a suitable offset source handy the mixer ports can be driven in near quadrature by the same signal and the dc output as a function of the relative phase shift between the 2 mixer inputs can be used. However neither method calibrates the phase noise frequency response of the system. Adding RF noise to one of the mixer inputs can be used to measure the frequency response of the system. If the RF noise source is uncalibrated but stable then it can be used to measure the relative frequency response. The results of a dc (or beat frequency) measurement of the gain can then be used to correct the results to obtain a calibrated frequency response. If one is using a capacitive or other non conventional mixer IF port termination, then knowing the relative frequency response can be vital. Bruce Bob Camp wrote: Hi I've always calibrated my phase noise setups to the phase slope of the mixer I'm using. It does involve switching gains, but it's a direct system calibration. Beat note is 360 degrees, so this chunk is x degrees and you got y mv over that chunk. Check the slope on the other side of the beat note to make sure it's the same. Do some math and you have a radian to volt transfer function. If you are sorting junk box OCXO's it's a pretty good way to do it. The only added steps are an independent measurement of the switched gain / gain flatness and a short circuit input check to estimate the noise floor. Both are an initial setup / one time only sort of thing with most amps. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Tuesday, August 24, 2010 3:25 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Phase noise measurement (was - no subject) Bob Camp wrote: Hi CHOP Being able to calibrate the preamp + sound card frequency response using the thermal noise of a resistor is convenient. This is more difficult to achieve with a bipolar input stage as the amplifier input current noise is significant. 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] Phase noise measurement (was - no subject)
Hi For a one time frequency response check, a directional coupler and a signal generator do a pretty good job of creating a useful test tone. Bob On Aug 24, 2010, at 4:03 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Having a simple method of determining the preamp frequency response can be a useful diagnostic tool during development, particularly if one uses componets like super capacitors in the amplifier signal path. If one doesnt have a suitable offset source handy the mixer ports can be driven in near quadrature by the same signal and the dc output as a function of the relative phase shift between the 2 mixer inputs can be used. However neither method calibrates the phase noise frequency response of the system. Adding RF noise to one of the mixer inputs can be used to measure the frequency response of the system. If the RF noise source is uncalibrated but stable then it can be used to measure the relative frequency response. The results of a dc (or beat frequency) measurement of the gain can then be used to correct the results to obtain a calibrated frequency response. If one is using a capacitive or other non conventional mixer IF port termination, then knowing the relative frequency response can be vital. Bruce Bob Camp wrote: Hi I've always calibrated my phase noise setups to the phase slope of the mixer I'm using. It does involve switching gains, but it's a direct system calibration. Beat note is 360 degrees, so this chunk is x degrees and you got y mv over that chunk. Check the slope on the other side of the beat note to make sure it's the same. Do some math and you have a radian to volt transfer function. If you are sorting junk box OCXO's it's a pretty good way to do it. The only added steps are an independent measurement of the switched gain / gain flatness and a short circuit input check to estimate the noise floor. Both are an initial setup / one time only sort of thing with most amps. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Tuesday, August 24, 2010 3:25 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Phase noise measurement (was - no subject) Bob Camp wrote: Hi CHOP Being able to calibrate the preamp + sound card frequency response using the thermal noise of a resistor is convenient. This is more difficult to achieve with a bipolar input stage as the amplifier input current noise is significant. 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] Phase noise measurement (was - no subject)
Von: Bob Camp li...@rtty.us If you start with a mixer that runs 500 mV / radian (an RPD-1 at the typical 8 mV / degree + 10%) then -180 below that would be 0.5 nV. Since noise it coherent close in, the DSB to SSB process nets you 1 nV out when you have -180 dbc noise. Adding the two sidebands may double the power, but not the voltage? 73, 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] Phase noise measurement (was - no subject)
Hi If the sidebands are un-correlated noise then they add as power (3db). If they are correlated they add as voltage (6db). Noisy modulation processes produce correlated sidebands. Close in noise likely comes from a modulation process. Far removed noise is unlikely to be a result of modulation. Bob On Aug 24, 2010, at 4:24 PM, dk...@arcor.de wrote: Von: Bob Camp li...@rtty.us If you start with a mixer that runs 500 mV / radian (an RPD-1 at the typical 8 mV / degree + 10%) then -180 below that would be 0.5 nV. Since noise it coherent close in, the DSB to SSB process nets you 1 nV out when you have -180 dbc noise. Adding the two sidebands may double the power, but not the voltage? 73, 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. ___ 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] Phase noise measurement (was - no subject)
NXP BF862, available from digi-key. Don't these devices have relatively high flicker noise? 1/f corner is well below 100 Hz. Look at the noise voltage plots of that audio guy I cited. My results for the BF862 were the same shape, absolutely somewhat worse in amplitude because I wanted a differential input and less FETs in parallel. Most of my BF862 had abt. 12 mA IDss, btw. The input capacitance is relatively noncritical in this application (phase noise measurement) since it is shunted by the much larger output capacitance of the low pass filter at the mixer IF port. The 300 pF Cin of a single IF3602 could seriously detune the input low pass and the 200 pF feedback capacitance in a stage with substantial voltage gain would destroy the bandwidth unless cascoding is provided. I think, I'll test some Analog Devices ADA9848-2 in parallel. It's hard to beat that combination of noise, 1/f, bandwidth, offset stability and price. Such a preamp can be used as an add-on to a scope or FFT-Analyzer, too, to characterize power supplies, references or oscillator bias circuits. It's fun to enter 60 dB probe gain into a scope channel menu and still see usable traces with uV/div scale factors. ( with a low pass, of course) There are noise nuts, too! ;-) Gerhard One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 ___ 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] Phase noise measurement (was - no subject)
I think, I'll test some Analog Devices ADA9848-2 in parallel. It's hard to beat that combination of noise, 1/f, bandwidth, offset stability and price. Oooops, ADA4898-2 http://www.analog.com/en/amplifiers-and-comparators/operational-amplifiers-op-amps/ada4898-2/products/product.html sorry for the confusion, Charles! 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] Phase noise measurement (was - no subject)
The link isnt particularly useful as guests cant view the attachments and registration is disabled Bruce dk...@arcor.de wrote: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. 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] Phase noise measurement (was - no subject)
http://www.synaesthesia.ca/LNschematics.html Is a better link, in that one can actually view the circuit schematics. There are a few simple refinements that will dramatically improve the low frequency PSRR of the single ended JFET circuits in the HPS5.1: 1) split the 3k3 resistor feeding the green LEDs into into 2 series 1k6 resistors and bypass the common node of these 2 resistors to ground. This low pass filters the noise current flowing in the LEDs due to power supply noise. 2) It would probably be even more effective if the base of the cascode transistor were driven by a voltage equal to the JFET source voltage plus about 3.7V. It should, for example, be possible to use a selected JFET to do this. 3) The output servo should drive the noninverting input of the opamp via a CBCS cascode (or equivalent) with a load resistor connected to the input stage positive supply rail. This should improve the PSRR dramatically. I use something similar in one of my low noise preamps albeit with a few LEDs in series with the resistor to provide most of the voltage drop as in my case the required voltage drop is reasonably predictable. This reduces the noise contribution from the servo integrator. Bruce Bruce Griffiths wrote: The link isnt particularly useful as guests cant view the attachments and registration is disabled Bruce dk...@arcor.de wrote: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. 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. ___ 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] Phase noise measurement (was - no subject)
The noise measurements for the HPSs 5.1 preamp: http://www.synaesthesia.ca/LNmeasurements.html indicate that while the high frequency noise is about 2.2x lower than an optimised single ended 2SK369 preamp its flicker noise is far higher. If one uses 5 2SK369's connected in parallel the flicker noise should be even lower whilst the high frequency noise will be comparable/ If the feedback resistor values are reduced perhaps 3 @SK369BLs will suffice. Even lower flicker noise should be achievable if IF9030s are substituted for the 2SK369s. Bruce Bruce Griffiths wrote: http://www.synaesthesia.ca/LNschematics.html Is a better link, in that one can actually view the circuit schematics. There are a few simple refinements that will dramatically improve the low frequency PSRR of the single ended JFET circuits in the HPS5.1: 1) split the 3k3 resistor feeding the green LEDs into into 2 series 1k6 resistors and bypass the common node of these 2 resistors to ground. This low pass filters the noise current flowing in the LEDs due to power supply noise. 2) It would probably be even more effective if the base of the cascode transistor were driven by a voltage equal to the JFET source voltage plus about 3.7V. It should, for example, be possible to use a selected JFET to do this. 3) The output servo should drive the noninverting input of the opamp via a CBCS cascode (or equivalent) with a load resistor connected to the input stage positive supply rail. This should improve the PSRR dramatically. I use something similar in one of my low noise preamps albeit with a few LEDs in series with the resistor to provide most of the voltage drop as in my case the required voltage drop is reasonably predictable. This reduces the noise contribution from the servo integrator. Bruce Bruce Griffiths wrote: The link isnt particularly useful as guests cant view the attachments and registration is disabled Bruce dk...@arcor.de wrote: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. 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] Phase noise measurement (was - no subject)
Hi I have the Hp phase noise system with the 35601A but use most the time the Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? Thanks Bert Kehren In a message dated 8/20/2010 6:54:05 P.M. Eastern Daylight Time, jmi...@pop.net writes: Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? You can always build HF isolation amps by rigging MMICs and attenuators together, but this will not reliably get you below -160 dBc/Hz. Bruce G. has given some good advice in this regard, with some circuit designs at http://www.ko4bb.com/~bruce/IsolationAmplifiers.html and elsewhere. I'm a fan of this version (also from Bruce): http://www.ke5fx.com/norton.htm This one has the advantage of simplicity. No weird parts, nothing that is likely to be out of production or hard to find, and dirt cheap. I've measured the broadband floor at near -170 dBc/Hz at 10 MHz, and its noise contribution at 100 Hz is below what the 3048A can see. These figures are adequate to measure any 10811-class OCXOs. A practical PN measurement system for 10811-class oscillators can be made by building two of those amplifiers and using them to drive pretty much any random double-balanced mixer found on eBay with +10 dBm LO specs or more. Both ports should be driven strongly to reject AM artifacts and avoid degrading the excellent noise floor offered by the amps. I'd hit the LO port with +10 to +12 dBm and the RF port with at least 0 dBm. Then, see the Wenzel app note here ( http://www.wenzel.com/documents/measuringphasenoise.htm ) to lock the two oscillators in quadrature and amplify the resulting baseband output. Any of several sound-card FFT programs can be used to generate an output graph, although if you want absolute calibration in dBc/Hz you need to be prepared to sweep the actual test setup from mixer output to FFT input to watch for various sources of flatness error. A combination of an AD7760-EVAL board and a Digilent Nexys2 can be used to construct an excellent baseband digitizer for the DC-1 MHz spectrum, but most of the time a good-quality 192-kHz sound card is fine for this sort of work. Most good crystal oscillators reach their broadband floor by 10 kHz, so there's no real need to go out to 1 MHz or more. -- john, KE5FX ___ 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] Phase noise measurement (was - no subject)
http://cgi.ebay.com/5-pcs-N-Channel-Transistor-2SK369-K369-Low-Noise-BL-/150471697656 Stanley - Original Message From: ewkeh...@aol.com ewkeh...@aol.com To: time-nuts@febo.com Sent: Sat, August 21, 2010 6:07:25 AM Subject: Re: [time-nuts] Phase noise measurement (was - no subject) Hi I have the Hp phase noise system with the 35601A but use most the time the Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? Thanks Bert Kehren In a message dated 8/20/2010 6:54:05 P.M. Eastern Daylight Time, jmi...@pop.net writes: Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? You can always build HF isolation amps by rigging MMICs and attenuators together, but this will not reliably get you below -160 dBc/Hz. Bruce G. has given some good advice in this regard, with some circuit designs at http://www.ko4bb.com/~bruce/IsolationAmplifiers.html and elsewhere. I'm a fan of this version (also from Bruce): http://www.ke5fx.com/norton.htm This one has the advantage of simplicity. No weird parts, nothing that is likely to be out of production or hard to find, and dirt cheap. I've measured the broadband floor at near -170 dBc/Hz at 10 MHz, and its noise contribution at 100 Hz is below what the 3048A can see. These figures are adequate to measure any 10811-class OCXOs. A practical PN measurement system for 10811-class oscillators can be made by building two of those amplifiers and using them to drive pretty much any random double-balanced mixer found on eBay with +10 dBm LO specs or more. Both ports should be driven strongly to reject AM artifacts and avoid degrading the excellent noise floor offered by the amps. I'd hit the LO port with +10 to +12 dBm and the RF port with at least 0 dBm. Then, see the Wenzel app note here ( http://www.wenzel.com/documents/measuringphasenoise.htm ) to lock the two oscillators in quadrature and amplify the resulting baseband output. Any of several sound-card FFT programs can be used to generate an output graph, although if you want absolute calibration in dBc/Hz you need to be prepared to sweep the actual test setup from mixer output to FFT input to watch for various sources of flatness error. A combination of an AD7760-EVAL board and a Digilent Nexys2 can be used to construct an excellent baseband digitizer for the DC-1 MHz spectrum, but most of the time a good-quality 192-kHz sound card is fine for this sort of work. Most good crystal oscillators reach their broadband floor by 10 kHz, so there's no real need to go out to 1 MHz or more. -- john, KE5FX ___ 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] Phase noise measurement (was - no subject)
The Wenzel Audio amp is a little noisier than it need be and it has a poor PSRR, so that a very low noise power supply with low ripple is essential. Its not too hard to improve the PSRR and the input noise of such a current feedback amplifier. There are JFETS (IF9030) with similar noise floors and significantly lower flicker noise. However the minimum order from Interfet is about $250. For noise measurements on several JFETS (including the IF9030 and the 2SK369) see: /Ultra-Low-Noise High Input Impedance Amplifier for Low-Frequency Measurement Applications/ Felix A Levinson, IEEE Transactions on Circuits and Systems Vol 55 No 7, August 2008 pp1815-1821. Bruce ewkeh...@aol.com wrote: Hi I have the Hp phase noise system with the 35601A but use most the time the Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? Thanks Bert Kehren In a message dated 8/20/2010 6:54:05 P.M. Eastern Daylight Time, jmi...@pop.net writes: Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? You can always build HF isolation amps by rigging MMICs and attenuators together, but this will not reliably get you below -160 dBc/Hz. Bruce G. has given some good advice in this regard, with some circuit designs at http://www.ko4bb.com/~bruce/IsolationAmplifiers.html and elsewhere. I'm a fan of this version (also from Bruce): http://www.ke5fx.com/norton.htm This one has the advantage of simplicity. No weird parts, nothing that is likely to be out of production or hard to find, and dirt cheap. I've measured the broadband floor at near -170 dBc/Hz at 10 MHz, and its noise contribution at 100 Hz is below what the 3048A can see. These figures are adequate to measure any 10811-class OCXOs. A practical PN measurement system for 10811-class oscillators can be made by building two of those amplifiers and using them to drive pretty much any random double-balanced mixer found on eBay with +10 dBm LO specs or more. Both ports should be driven strongly to reject AM artifacts and avoid degrading the excellent noise floor offered by the amps. I'd hit the LO port with +10 to +12 dBm and the RF port with at least 0 dBm. Then, see the Wenzel app note here ( http://www.wenzel.com/documents/measuringphasenoise.htm ) to lock the two oscillators in quadrature and amplify the resulting baseband output. Any of several sound-card FFT programs can be used to generate an output graph, although if you want absolute calibration in dBc/Hz you need to be prepared to sweep the actual test setup from mixer output to FFT input to watch for various sources of flatness error. A combination of an AD7760-EVAL board and a Digilent Nexys2 can be used to construct an excellent baseband digitizer for the DC-1 MHz spectrum, but most of the time a good-quality 192-kHz sound card is fine for this sort of work. Most good crystal oscillators reach their broadband floor by 10 kHz, so there's no real need to go out to 1 MHz or more. -- john, KE5FX ___ 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] Phase noise measurement (was - no subject)
On all phase noise measurements I use AGM batteries. specially for the signal source to be measured. Keep six 12 V batteries for that around, every thing from 7 to 20 Amps. Bert In a message dated 8/21/2010 7:33:57 A.M. Eastern Daylight Time, bruce.griffi...@xtra.co.nz writes: The Wenzel Audio amp is a little noisier than it need be and it has a poor PSRR, so that a very low noise power supply with low ripple is essential. Its not too hard to improve the PSRR and the input noise of such a current feedback amplifier. There are JFETS (IF9030) with similar noise floors and significantly lower flicker noise. However the minimum order from Interfet is about $250. For noise measurements on several JFETS (including the IF9030 and the 2SK369) see: /Ultra-Low-Noise High Input Impedance Amplifier for Low-Frequency Measurement Applications/ Felix A Levinson, IEEE Transactions on Circuits and Systems Vol 55 No 7, August 2008 pp1815-1821. Bruce ewkeh...@aol.com wrote: Hi I have the Hp phase noise system with the 35601A but use most the time the Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? Thanks Bert Kehren In a message dated 8/20/2010 6:54:05 P.M. Eastern Daylight Time, jmi...@pop.net writes: Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? You can always build HF isolation amps by rigging MMICs and attenuators together, but this will not reliably get you below -160 dBc/Hz. Bruce G. has given some good advice in this regard, with some circuit designs at http://www.ko4bb.com/~bruce/IsolationAmplifiers.html and elsewhere. I'm a fan of this version (also from Bruce): http://www.ke5fx.com/norton.htm This one has the advantage of simplicity. No weird parts, nothing that is likely to be out of production or hard to find, and dirt cheap. I've measured the broadband floor at near -170 dBc/Hz at 10 MHz, and its noise contribution at 100 Hz is below what the 3048A can see. These figures are adequate to measure any 10811-class OCXOs. A practical PN measurement system for 10811-class oscillators can be made by building two of those amplifiers and using them to drive pretty much any random double-balanced mixer found on eBay with +10 dBm LO specs or more. Both ports should be driven strongly to reject AM artifacts and avoid degrading the excellent noise floor offered by the amps. I'd hit the LO port with +10 to +12 dBm and the RF port with at least 0 dBm. Then, see the Wenzel app note here ( http://www.wenzel.com/documents/measuringphasenoise.htm ) to lock the two oscillators in quadrature and amplify the resulting baseband output. Any of several sound-card FFT programs can be used to generate an output graph, although if you want absolute calibration in dBc/Hz you need to be prepared to sweep the actual test setup from mixer output to FFT input to watch for various sources of flatness error. A combination of an AD7760-EVAL board and a Digilent Nexys2 can be used to construct an excellent baseband digitizer for the DC-1 MHz spectrum, but most of the time a good-quality 192-kHz sound card is fine for this sort of work. Most good crystal oscillators reach their broadband floor by 10 kHz, so there's no real need to go out to 1 MHz or more. -- john, KE5FX ___ 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] Phase noise measurement (was - no subject)
In message 4a8e.56751f36.39a11...@aol.com, ewkeh...@aol.com writes: On all phase noise measurements I use AGM batteries. Be aware that chemical batteries can be incredibly noisy, in particular wet or semi-wet types. It is not periodic noise, so for PN measurements with sensible averaging periods it probably does not matter. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Phase noise measurement (was - no subject)
On 22 August 2010 00:07, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 4a8e.56751f36.39a11...@aol.com, ewkeh...@aol.com writes: On all phase noise measurements I use AGM batteries. Be aware that chemical batteries can be incredibly noisy, in particular wet or semi-wet types. Dilithium Crystals are the only way to go on this. Just bolt a good sized one in the Warp drive and feed the cross-phase out though the interplanator and you get some really quiet power. Just be careful not to short it out or we will all have a bit of you come to visit us :) Steve It is not periodic noise, so for PN measurements with sensible averaging periods it probably does not matter. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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. -- Steve Rooke - ZL3TUV G8KVD The only reason for time is so that everything doesn't happen at once. - Einstein ___ 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] Phase noise measurement (was - no subject)
I am not seeing it, what should I use to measure it 3561 and 7 spec analyzer do not show it? Bert In a message dated 8/21/2010 8:07:41 A.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 4a8e.56751f36.39a11...@aol.com, ewkeh...@aol.com writes: On all phase noise measurements I use AGM batteries. Be aware that chemical batteries can be incredibly noisy, in particular wet or semi-wet types. It is not periodic noise, so for PN measurements with sensible averaging periods it probably does not matter. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Phase noise measurement (was - no subject)
Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. 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] Phase noise measurement (was - no subject)
Hi A simple gain of 20 (26 db) amp using an OP-37 does a pretty good job in front of a spectrum analyzer. For a sound card you need more gain. Bob On Aug 21, 2010, at 11:42 AM, dk...@arcor.de wrote: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. 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. ___ 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] Phase noise measurement (was - no subject)
Thanks Bert In a message dated 8/21/2010 11:43:53 A.M. Eastern Daylight Time, dk...@arcor.de writes: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. 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. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote: The AMC-123 can also be homebrewed by reading the patent, which is listed on the data sheet. I found it here: http://www.freepatentsonline.com/3624536.pdf Having read the patent, I find I'm still weak enough in the area of discrete amplifier design that I'd have low confidence of creating an amplifier with the required phase noise, gain, isolation and compression specifications. Assuming the simple amplifier in Figure 1, I think I'm make or break the design (more likely the latter) by selecting a suitable in-production replacement for the 2N5109, figuring out the required turns ratio of autotransformer L1, biasing the transistor amplifier correctly, etc. I'd have no problem building it; if I identified off-the-shelf magnetics then I could even build a whole bunch of them, as I design PCBs for a living (mostly GPS stuff; I can lay out the microwave stuff as long as a smart RF guy comes up with the necessary LNA circuit topology), and I even have a bit of experience designing mechanical stuff (i.e., in case it wanted to be in a nice machined aluminum shield/heat-sink box, though my CNC mill is presently in pieces so I'd need to farm out mechanical fabrication). I'm just weak in the analog/RF design area so far. Since the Q: Which amplifier? A: AMC-123! thing appears to be a FAQ, and that patent may be old enough to have expired, I wonder if the world wants a nice plug-and-play TIME-NUTS-123 amplifier based on the Norton patent, designed with currently-available off-the-shelf components (aside from the custom PCB and possibly enclosure), which could be made in smallish batches, characterized by somebody with the right equipment, and sold at a reasonable price to help folks cobble together their home-brewed phase noise measurement and frequency reference distribution systems. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 3:41 PM, Rick Karlquist wrote: It might still be available through Tyco/MAcom. They have continued to make selected Anzac components. There was also an AM-123, which was a TO-something can version. My first quick scan didn't turn up any offered for sale, though I did dig up the datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/184840/MACOM/AM-123/+074853VKvwOxcER.tvC+/datasheet.pdf -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 5:11 PM, John Miles wrote: Also, it looks like you (Mark) are only about an hour from Cerritos, where the MUD ( http://www.microwaveupdate.org ) conference will be held at the end of October. This could be one option for you. As part of the $35 registration cost, you get access to a test lab set up to help attendees measure noise figure, PN, etc. on any homebrew or commercial gear they wish to bring. Interesting. I still think I'd like to be able to measure low phase noise signal sources at home if practical. In particular, I've been toying with the idea of starting my own little company on the side, making and selling ham-radio-related/test-equipment-related stuff that seems to be missing from the market, as a (probably small but hopefully positive) secondary source of income and an excuse to design, build, accumulate (and deduct!) fun electronic equipment. My desire to learn to characterize phase noise stems from the idea that some of my products would be things whose phase noise should be specified, and it wouldn't be right for me to leech off other people's test equipment and effort if I plan to make a buck at it. Thus, I feel the need to learn how to do it myself, and then use that ability to add some value to the world in some manner. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
In message 7c37.12cdef25.39a12...@aol.com, ewkeh...@aol.com writes: I am not seeing it, what should I use to measure it 3561 and 7 spec analyzer do not show it? It is probably the 3561 not the 70k that has the best chance. I am not aware of the precise characteristics of the noise, but it sounds somewhat like a boiling pot. I became aware of it first time when I ran a small class-A audio amplifier from a couple of, probably too, small VRLA's some years ago, just for the fun of it. With no input signal, the speakers would gurgle faintly and it took me some time to locate the source of the noise to the batteries. I would guess its amplitude correlates with the ratio of discharge current to plate area, since it is chemical/mechanical in nature. These days, I would build a super-cap battery instead if I needed a low-power PSU with low noise. Poul-Henning PS: also be aware that almost all VRLA's have a very nasty resonance frequency somewhere in the low MHz band. If you are after low noise, you should always decouple the battery good poly/plastic caps right at the terminals. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Phase noise measurement (was - no subject)
Hi I suspect you will have to hand wind the magnetics. The 5109 was still in production last time I shopped for them. Bob On Aug 21, 2010, at 1:52 PM, Mark J. Blair n...@nf6x.net wrote: On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote: The AMC-123 can also be homebrewed by reading the patent, which is listed on the data sheet. I found it here: http://www.freepatentsonline.com/3624536.pdf Having read the patent, I find I'm still weak enough in the area of discrete amplifier design that I'd have low confidence of creating an amplifier with the required phase noise, gain, isolation and compression specifications. Assuming the simple amplifier in Figure 1, I think I'm make or break the design (more likely the latter) by selecting a suitable in-production replacement for the 2N5109, figuring out the required turns ratio of autotransformer L1, biasing the transistor amplifier correctly, etc. I'd have no problem building it; if I identified off-the-shelf magnetics then I could even build a whole bunch of them, as I design PCBs for a living (mostly GPS stuff; I can lay out the microwave stuff as long as a smart RF guy comes up with the necessary LNA circuit topology), and I even have a bit of experience designing mechanical stuff (i.e., in case it wanted to be in a nice machined aluminum shield/heat-sink box, though my CNC mill is presently in pieces so I'd need to farm out mechanical fabrication). I'm just weak in the analog/RF design area so far. Since the Q: Which amplifier? A: AMC-123! thing appears to be a FAQ, and that patent may be old enough to have expired, I wonder if the world wants a nice plug-and-play TIME-NUTS-123 amplifier based on the Norton patent, designed with currently-available off-the-shelf components (aside from the custom PCB and possibly enclosure), which could be made in smallish batches, characterized by somebody with the right equipment, and sold at a reasonable price to help folks cobble together their home-brewed phase noise measurement and frequency reference distribution systems. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
Hi There are a number of articles on the web detailing the art of getting one of these to work. Since it's broad band feedback you need to be a little careful with the layout and the transformer. Bob On Aug 21, 2010, at 2:50 PM, Mark J. Blair n...@nf6x.net wrote: On Aug 21, 2010, at 11:30 AM, Bob Camp wrote: I suspect you will have to hand wind the magnetics. Ah, bummer. I thought that the two 1:5 transformers specified in the patent might be realized with this part for an amplifier for use at 10 MHz only: http://minicircuits.com/pdfs/TT25-1.pdf However, I got the feeling that autotransformer L1 might need some odd turns ratio to get the impedance matching right. Am I anywhere close to making sense, or am I still droolingly clueless? :) The 5109 was still in production last time I shopped for them. I didn't find them at Digi-Key, but I just looked at Mouser and found them still available, made by Central Semiconductor: http://www.centralsemi.com/PDFs/products/2n5109.pdf I'm so accustomed to tiny surface-mount stuff in my day job, that I'm always surprised to find anything through-hole still in production! -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
On Aug 21, 2010, at 12:04 PM, Bob Camp wrote: There are a number of articles on the web detailing the art of getting one of these to work. Since it's broad band feedback you need to be a little careful with the layout and the transformer. Thanks, I'll continue digging. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
It's still being made by Tyco / MaCOM: http://www.macomtech.com/datasheets/AM-123_AMC-123.pdf Adrian Mark J. Blair schrieb: On Aug 20, 2010, at 3:41 PM, Rick Karlquist wrote: It might still be available through Tyco/MAcom. They have continued to make selected Anzac components. There was also an AM-123, which was a TO-something can version. My first quick scan didn't turn up any offered for sale, though I did dig up the datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/184840/MACOM/AM-123/+074853VKvwOxcER.tvC+/datasheet.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] Phase noise measurement (was - no subject)
On Aug 21, 2010, at 12:10 PM, Adrian wrote: It's still being made by Tyco / MaCOM: http://www.macomtech.com/datasheets/AM-123_AMC-123.pdf Thanks! According to Avnet (the only one of their US distributors where I found a price posted online), the price is around $600 each at quantity 5 for the SMA connector version. !! I think I'll continue investigating a homebrew implementation for now! -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
ewkeh...@aol.com wrote: Thanks Bert In a message dated 8/21/2010 11:43:53 A.M. Eastern Daylight Time, dk...@arcor.de writes: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. Don't these devices have relatively high flicker noise? I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. The input capacitance is relatively noncritical in this application (phase noise measurement) since it is shunted by the much larger output capacitance of the low pass filter at the mixer IF port. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. regards, Gerhard 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] Phase noise measurement (was - no subject)
Poul-Henning Kamp wrote: In message7c37.12cdef25.39a12...@aol.com, ewkeh...@aol.com writes: I am not seeing it, what should I use to measure it 3561 and 7 spec analyzer do not show it? It is probably the 3561 not the 70k that has the best chance. I am not aware of the precise characteristics of the noise, but it sounds somewhat like a boiling pot. I became aware of it first time when I ran a small class-A audio amplifier from a couple of, probably too, small VRLA's some years ago, just for the fun of it. With no input signal, the speakers would gurgle faintly and it took me some time to locate the source of the noise to the batteries. I would guess its amplitude correlates with the ratio of discharge current to plate area, since it is chemical/mechanical in nature. These days, I would build a super-cap battery instead if I needed a low-power PSU with low noise. Poul-Henning PS: also be aware that almost all VRLA's have a very nasty resonance frequency somewhere in the low MHz band. If you are after low noise, you should always decouple the battery good poly/plastic caps right at the terminals. NIST found that NiCd cells are very quiet at least for low load currents: http://tf.nist.gov/general/pdf/1133.pdf Thus batteries are useful as low noise voltage references or for providing the relatively low base current of a BJT in a low phase noise RF amplifier. Perhaps its the gelled electrolyte that is the source of the noise problem with VLRA batteries?? 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] Phase noise measurement (was - no subject)
In message 4c703124.20...@xtra.co.nz, Bruce Griffiths writes: Poul-Henning Kamp wrote: NIST found that NiCd cells are very quiet at least for low load currents: http://tf.nist.gov/general/pdf/1133.pdf Too bad they didn't include lead-acid in that test... Perhaps its the gelled electrolyte that is the source of the noise problem with VLRA batteries?? The batteries I used were pre-owned AGM, and apart from possibly the frequency spectrum, I wouldn't expect AGM/Gel to make any significant difference. The very few hints I have been able to find, talk about bubbles and mechanical shifts in the particulate matter in the electrodes but they were all trying to divine battery health from these entrails, rather than measuring the absolute magnitude of the problem. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Phase noise measurement (was - no subject)
That's not really a surprise. Alone the hermetically sealed flatpack housings don't make these a bargain... There's nothing wrong with building your own. Btw. there was an article in the German 'UKW-Berichte' (VHF Communications) 4/1977 featuring a two stage BFT66 + BFR34A Norton amp for 144 and 432 MHz. Adrian Mark J. Blair schrieb: On Aug 21, 2010, at 12:10 PM, Adrian wrote: It's still being made by Tyco / MaCOM: http://www.macomtech.com/datasheets/AM-123_AMC-123.pdf Thanks! According to Avnet (the only one of their US distributors where I found a price posted online), the price is around $600 each at quantity 5 for the SMA connector version. !! I think I'll continue investigating a homebrew implementation for now! ___ 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] Phase noise measurement (was - no subject)
Hi One thing to head back to here: What is being measured? If the DUT is only as good as a 10811 and you have a 3561a, an AD797 is overkill. That assumes you are running a RPD-1 or a high level mixer with buffers. There aren't a lot of oscillators on the surplus market that will need much better. Super amps are fine. They just are a bit beyond the minimum required to get going. Bob On Aug 21, 2010, at 3:47 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: ewkeh...@aol.com wrote: Thanks Bert In a message dated 8/21/2010 11:43:53 A.M. Eastern Daylight Time, dk...@arcor.de writes: Wenzel Audio Amp referred to in this email. Perfect! I drive with it a 3561A and a 7L5! Works for me. The only problem is getting any more 2SK369. Any recommendations? NXP BF862, available from digi-key. Don't these devices have relatively high flicker noise? I have used it in a similar hookup with good success. Its virtue is the low noise voltage AND low input capacitance at the same time. You could deploy MANY of them in parallel until you get into the capacitance range of a single Interfet device. The input capacitance is relatively noncritical in this application (phase noise measurement) since it is shunted by the much larger output capacitance of the low pass filter at the mixer IF port. One heroic effort for audio is here: http://www.diy-audio-engineering.org/index.php?board=2.0 HPS5.1 I currently use 3 pairs of SSM2210 in front of a AD797. regards, Gerhard 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.
[time-nuts] Phase noise measurement (was - no subject)
Mark You've come to the right place - well, that is if you want to devote a significant amount of your life in the pursuit of ever-more accurate time and frequency measurements If you've only got one source then you need to use the frequency discriminator method (aka delay line method) of phase noise measurement. Basically you take the output of the source, split it in two, delay one of the signals, re-combine the two and then measure the resultant signal on a base-band spectrum analyser. There are loads of references to this on the web, which describe the method in more detail, including :- The Art of phase noise measurement - Dieter Scherer and HP Application Note AN270-2 both available from John Miles web site www.thegleam.com/ke5fx/gpib/pn.htm The references at the end of these articles, especially the HP ones, are particularly useful. The operating manual for the HP 11729B or 11729C Carrier Noise Test Set is also highly recommended. Yes, there's some maths, you need to understand the relationship between phase and frequency measurements, but you don't necessarily need ALL the theory that most of the papers give - don't give up just because of a few differential equations :) The limitation of the frequency discriminator method is that the noise floor of the measurement system is often worse than the DUT, especially if your DUT is very good, and it's even worse if you're trying to measure close-in noise. The Sherer article gives a good graph illustrating this. If you're trying to measure the phase noise of the oscillator inside a Tbolt then I don't think that a frequency discriminator will be sensitive enough, although I might be wrong. Despite what you said, you might want to consider buying an HP 10811 oscillator or similar which you could use in a phase detector measurement system which is likely to give superior results. Hope that helps regards Grant Mark wrote :- My new GPSDO leaves me with the question of how do I measure the phase noise of what is by far the best oscillator I own... without buying a better one to compare it to. That question is what brought me to time-nuts. I'm starting to read some papers on oscillator characterization that are collected together in a technical note from NIST that a co-worker pointed me towards, but some of them are giving me a math-induced headache. ___ 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] Phase noise measurement (was - no subject)
Mark, you have the following options: - HP (Agilent) E5052A/B or RS FSUP Signal Source Analyzer (works for a single DUT, though limited to 1 Hz offset, normally useful for 10 Hz up to 40 MHz). - Compare two identical DUT's with a HP 3048A or similar PN test system and subtract 3 dB, assuming that the PN characteristic of both DUT's is identical. - Compare 3 similar DUT's with a HP 3048A and calculate the individual PN using the three cornerd hat method. - set up a cross correlation PN measurement system similar to the E5052A and have fun. You will however need two - as good as possible, but preferaby not more than 10 dB worse than what you want to measure - VCXO's like HP 10811A's... - you may build your own HP 3048A alike system, but be prepared to invest serious money and time, and much more time than you thought in the beginning... (if that is what you're after, you'll have the most fun you can). - find someone who has one of the above and talk him into measuring yours. - search the web for published PN data of the model you have and take these as a reference (give or take a few dB). Btw. do not assume that the phase noise of a disciplined VCXO is the same as the VCXO alone. Also keep the power supply contribution into account that can be surprisingly high. And, the PN of most frequency standards is significantly lower than what you can measure with any spectrum analyzer with PN measurement software (except for the RS FSUP of course). Adrian Grant Hodgson schrieb: Mark You've come to the right place - well, that is if you want to devote a significant amount of your life in the pursuit of ever-more accurate time and frequency measurements If you've only got one source then you need to use the frequency discriminator method (aka delay line method) of phase noise measurement. Basically you take the output of the source, split it in two, delay one of the signals, re-combine the two and then measure the resultant signal on a base-band spectrum analyser. There are loads of references to this on the web, which describe the method in more detail, including :- The Art of phase noise measurement - Dieter Scherer and HP Application Note AN270-2 both available from John Miles web site www.thegleam.com/ke5fx/gpib/pn.htm The references at the end of these articles, especially the HP ones, are particularly useful. The operating manual for the HP 11729B or 11729C Carrier Noise Test Set is also highly recommended. Yes, there's some maths, you need to understand the relationship between phase and frequency measurements, but you don't necessarily need ALL the theory that most of the papers give - don't give up just because of a few differential equations :) The limitation of the frequency discriminator method is that the noise floor of the measurement system is often worse than the DUT, especially if your DUT is very good, and it's even worse if you're trying to measure close-in noise. The Sherer article gives a good graph illustrating this. If you're trying to measure the phase noise of the oscillator inside a Tbolt then I don't think that a frequency discriminator will be sensitive enough, although I might be wrong. Despite what you said, you might want to consider buying an HP 10811 oscillator or similar which you could use in a phase detector measurement system which is likely to give superior results. Hope that helps regards Grant Mark wrote :- My new GPSDO leaves me with the question of how do I measure the phase noise of what is by far the best oscillator I own... without buying a better one to compare it to. That question is what brought me to time-nuts. I'm starting to read some papers on oscillator characterization that are collected together in a technical note from NIST that a co-worker pointed me towards, but some of them are giving me a math-induced headache. ___ 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] Phase noise measurement (was - no subject)
Hi You can make a pretty good front end (mixer / amp / lock) for under $100. That will let you measure phase noise with an audio spectrum analyzer. Bob On Aug 20, 2010, at 10:40 AM, Adrian rfn...@arcor.de wrote: Mark, you have the following options: - HP (Agilent) E5052A/B or RS FSUP Signal Source Analyzer (works for a single DUT, though limited to 1 Hz offset, normally useful for 10 Hz up to 40 MHz). - Compare two identical DUT's with a HP 3048A or similar PN test system and subtract 3 dB, assuming that the PN characteristic of both DUT's is identical. - Compare 3 similar DUT's with a HP 3048A and calculate the individual PN using the three cornerd hat method. - set up a cross correlation PN measurement system similar to the E5052A and have fun. You will however need two - as good as possible, but preferaby not more than 10 dB worse than what you want to measure - VCXO's like HP 10811A's... - you may build your own HP 3048A alike system, but be prepared to invest serious money and time, and much more time than you thought in the beginning... (if that is what you're after, you'll have the most fun you can). - find someone who has one of the above and talk him into measuring yours. - search the web for published PN data of the model you have and take these as a reference (give or take a few dB). Btw. do not assume that the phase noise of a disciplined VCXO is the same as the VCXO alone. Also keep the power supply contribution into account that can be surprisingly high. And, the PN of most frequency standards is significantly lower than what you can measure with any spectrum analyzer with PN measurement software (except for the RS FSUP of course). Adrian Grant Hodgson schrieb: Mark You've come to the right place - well, that is if you want to devote a significant amount of your life in the pursuit of ever-more accurate time and frequency measurements If you've only got one source then you need to use the frequency discriminator method (aka delay line method) of phase noise measurement. Basically you take the output of the source, split it in two, delay one of the signals, re-combine the two and then measure the resultant signal on a base-band spectrum analyser. There are loads of references to this on the web, which describe the method in more detail, including :- The Art of phase noise measurement - Dieter Scherer and HP Application Note AN270-2 both available from John Miles web site www.thegleam.com/ke5fx/gpib/pn.htm The references at the end of these articles, especially the HP ones, are particularly useful. The operating manual for the HP 11729B or 11729C Carrier Noise Test Set is also highly recommended. Yes, there's some maths, you need to understand the relationship between phase and frequency measurements, but you don't necessarily need ALL the theory that most of the papers give - don't give up just because of a few differential equations :) The limitation of the frequency discriminator method is that the noise floor of the measurement system is often worse than the DUT, especially if your DUT is very good, and it's even worse if you're trying to measure close-in noise. The Sherer article gives a good graph illustrating this. If you're trying to measure the phase noise of the oscillator inside a Tbolt then I don't think that a frequency discriminator will be sensitive enough, although I might be wrong. Despite what you said, you might want to consider buying an HP 10811 oscillator or similar which you could use in a phase detector measurement system which is likely to give superior results. Hope that helps regards Grant Mark wrote :- My new GPSDO leaves me with the question of how do I measure the phase noise of what is by far the best oscillator I own... without buying a better one to compare it to. That question is what brought me to time-nuts. I'm starting to read some papers on oscillator characterization that are collected together in a technical note from NIST that a co-worker pointed me towards, but some of them are giving me a math-induced headache. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 4:56 AM, Grant Hodgson wrote: You've come to the right place - well, that is if you want to devote a significant amount of your life in the pursuit of ever-more accurate time and frequency measurements :) If you've only got one source then you need to use the frequency discriminator method (aka delay line method) of phase noise measurement. Basically you take the output of the source, split it in two, delay one of the signals, re-combine the two and then measure the resultant signal on a base-band spectrum analyser. [...] The limitation of the frequency discriminator method is that the noise floor of the measurement system is often worse than the DUT, especially if your DUT is very good, and it's even worse if you're trying to measure close-in noise. The Sherer article gives a good graph illustrating this. If you're trying to measure the phase noise of the oscillator inside a Tbolt then I don't think that a frequency discriminator will be sensitive enough, although I might be wrong. I got the impression that for good OCXOs like the HP 10811 or (supposedly) the OCXO in my TBolt, the delay line method wouldn't provide enough sensitivity for measuring close-in phase noise. Despite what you said, you might want to consider buying an HP 10811 oscillator or similar which you could use in a phase detector measurement system which is likely to give superior results. I might need 2 or 3 of them so I can weed out the under-performers! :) I had originally considered getting one of the surplus HP/Agilent GPSDOs with HP 10811 OCXOs, but I settled on the TBolt since it appeared to be almost as good (in terms of phase noise), a bit cheaper, and a bit easier to power than one of the HPs that need 48VDC. Well, I bought another power supply for the TBolt, anyway, but at least it would be easier to build a power supply that operates from +12VDC, a voltage that's always available in a ham shack. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 7:40 AM, Adrian wrote: - you may build your own HP 3048A alike system, but be prepared to invest serious money and time, and much more time than you thought in the beginning... (if that is what you're after, you'll have the most fun you can). I did a quick survey of surplus phase noise measurement system prices on eBay, and was shocked by how cheap they apparently aren't. I'll set up some searches to warn me when any of the instruments you mentioned appear, since it may be a while before the right one shows up at the right price. - Compare 3 similar DUT's with a HP 3048A and calculate the individual PN using the three cornerd hat method. That sounds like a method I'll want to learn about, since I'll necessarily be building up my testbench with surplus equipment of unknown condition, and the things I'd want to characterize initially would likely be the best oscillators I can get my hands on (except for the ones that no longer perform to spec, which I'd want to weed out). Once I have the bugs worked out of my test system, I could then use it to characterize other oscillators (probably far inferior to the Trimble/HP OCXOs) in practical applications. Btw. do not assume that the phase noise of a disciplined VCXO is the same as the VCXO alone. Also keep the power supply contribution into account that can be surprisingly high. In the case of my TBolt OCXO, I'll be interested in characterizing it while it's in the TBolt, with its regular power supply, and under discipline, since that's the way I'd be using it as a frequency reference on my bench. And, the PN of most frequency standards is significantly lower than what you can measure with any spectrum analyzer with PN measurement software (except for the RS FSUP of course). Yup, the phase noise plots I've seen of the HP and TBolt OCXOs show close-in phase noise very far beyond the dynamic range of any spectrum analyzers I'm familiar with. I wandered through the labs at work in hope of finding something I could use to look at the phase noise of my new toys (I'm in the GPS industry, and have access to some nice spectrum and network analyzers), but it looks like I'm on my own. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 8:30 AM, Bob Camp wrote: You can make a pretty good front end (mixer / amp / lock) for under $100. That will let you measure phase noise with an audio spectrum analyzer. I am intrigued by your ideas, and I would like to subscribe to your newsletter. Oh, wait, I've already subscribed to your newsletter. :-) -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
Mark J. Blair wrote: oscillator inside a Tbolt then I don't think that a frequency discriminator will be sensitive enough, although I might be wrong. I got the impression that for good OCXOs like the HP 10811 or (supposedly) the OCXO in my TBolt, the delay line method wouldn't provide enough sensitivity for measuring close-in phase noise. Right, the delay line method is a non-starter. Despite what you said, you might want to consider buying an HP 10811 oscillator or similar which you could use in a phase detector measurement system which is likely to give superior results. On the 10811 production line, they would use Anzac AMC-123 amplifiers to drive a +17 dBm mixer, and then amplify the IF output with a low noise current amplifier like the Linear LT1028. You can easily homebrew this setup. You will need to have a DC coupled connection to the IF output to make a narrow PLL that drives the EFC of one of the oscillators. You can use a PC based audio spectrum analyzer program to look at the phase noise output. You can break the PLL to get a beat note to calibrate the system. The AMC-123 can also be homebrewed by reading the patent, which is listed on the data sheet. No need at all to get a 3048, etc. Rick Karlquist N6RK ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote: On the 10811 production line, they would use Anzac AMC-123 amplifiers to drive a +17 dBm mixer, and then amplify the IF output with a low noise current amplifier like the Linear LT1028. You can easily homebrew this setup. You will need to have a DC coupled connection to the IF output to make a narrow PLL that drives the EFC of one of the oscillators. You can use a PC based audio spectrum analyzer program to look at the phase noise output. You can break the PLL to get a beat note to calibrate the system. The AMC-123 can also be homebrewed by reading the patent, which is listed on the data sheet. No need at all to get a 3048, etc. Interesting. I'm also the proud new owner of an Ettus Research USRP with a nice selection of RF front end boards, so maybe I could press that into service for spectrum analysis as long as I'm looking at things that will fall within its dynamic range and noise floor. I have a lot of learning to do... ;) -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
Hi Sounds like that's less than $100 on a home brew basis. There are several variations you could try. None of them break the bank. All do a quadrature test on a pair of OCXO's. Bob On Aug 20, 2010, at 2:17 PM, Rick Karlquist rich...@karlquist.com wrote: Mark J. Blair wrote: oscillator inside a Tbolt then I don't think that a frequency discriminator will be sensitive enough, although I might be wrong. I got the impression that for good OCXOs like the HP 10811 or (supposedly) the OCXO in my TBolt, the delay line method wouldn't provide enough sensitivity for measuring close-in phase noise. Right, the delay line method is a non-starter. Despite what you said, you might want to consider buying an HP 10811 oscillator or similar which you could use in a phase detector measurement system which is likely to give superior results. On the 10811 production line, they would use Anzac AMC-123 amplifiers to drive a +17 dBm mixer, and then amplify the IF output with a low noise current amplifier like the Linear LT1028. You can easily homebrew this setup. You will need to have a DC coupled connection to the IF output to make a narrow PLL that drives the EFC of one of the oscillators. You can use a PC based audio spectrum analyzer program to look at the phase noise output. You can break the PLL to get a beat note to calibrate the system. The AMC-123 can also be homebrewed by reading the patent, which is listed on the data sheet. No need at all to get a 3048, etc. Rick Karlquist N6RK ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote: On the 10811 production line, they would use Anzac AMC-123 amplifiers How does this amplifier look for this application? http://minicircuits.com/pdfs/ZFL-500LN.pdf If I understand the specifications properly, the noise figure is better and it has higher reverse isolation and higher gain, but a lower output intercept point. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
It is good that you asked this FAQ. Basically, what is magic about the AMC-123 is that it has certifiably low phase noise, guaranteed by design and characterization, although not specified by Anzac. The other 99.9% of amplifiers that seem plausible, like this one, do not have the sophisticated negative feedback scheme of the AMC-123, and likely do NOT have good enough phase noise. In any event, we have zero information about the phase noise of this Mini-Circuits amplifier. Having a low noise figure is necessary but not sufficient to have good phase noise. Of course you could always get lucky. But then you have to also build an amplifier phase noise measurement system, which generally entails a line stretcher. Again, thank you for asking this question. It comes up often. Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? Rick Karlquist N6RK Mark J. Blair wrote: On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote: On the 10811 production line, they would use Anzac AMC-123 amplifiers How does this amplifier look for this application? http://minicircuits.com/pdfs/ZFL-500LN.pdf If I understand the specifications properly, the noise figure is better and it has higher reverse isolation and higher gain, but a lower output intercept point. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
On Aug 20, 2010, at 2:19 PM, Rick Karlquist wrote: It is good that you asked this FAQ. Basically, what is magic about the AMC-123 is that it has certifiably low phase noise, guaranteed by design and characterization, although not specified by Anzac. [...] Having a low noise figure is necessary but not sufficient to have good phase noise. Ah, I see. Is the AMC-123 or an equivalent still in production, or was homebrewing brought up as an option because it's not? -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
to drive a +17 dBm mixer, and then amplify the IF output with a low noise current amplifier like the Linear LT1028. You can easily homebrew low noise _voltage_ ? 73, Gerhard dk4xp ___ 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] Phase noise measurement (was - no subject)
Rick, thank you again for having pointed me to the AMC123 that were just available when you mentioned them. Part of the magic is the 10 dB gain and typical +23 dBm output. So, you don't saturate it with a 10811, which would be bad in terms of phase noise, and, on the other hand, if you overdrive it accidentally, there is no risk to damage the +23 dBm mixer (phase detector) in the 11848A test set. There are some other interesting Anzac models featuring the lossless feedback design, but this one fits best. I was lucky to find some Q-Bit anps (QBH-137 and 138) that are based on an almost identical patent but, with 12 to 15 dB, have more gain and maybe slightly higher PN. Anzac patent: 3,624,536 which is the original David E. Norton patent from 1971. Q-Bit patent: 4,042,667 from 1977 http://www.freepatentsonline.com/4042887.pdf To comment on the Mini Circuits amp, for my needs it has way too much gain and +5 dBm 1 dB compression makes it completely useless for PN measurement purposes. Adrian Rick Karlquist schrieb: It is good that you asked this FAQ. Basically, what is magic about the AMC-123 is that it has certifiably low phase noise, guaranteed by design and characterization, although not specified by Anzac. The other 99.9% of amplifiers that seem plausible, like this one, do not have the sophisticated negative feedback scheme of the AMC-123, and likely do NOT have good enough phase noise. In any event, we have zero information about the phase noise of this Mini-Circuits amplifier. Having a low noise figure is necessary but not sufficient to have good phase noise. Of course you could always get lucky. But then you have to also build an amplifier phase noise measurement system, which generally entails a line stretcher. Again, thank you for asking this question. It comes up often. Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? Rick Karlquist N6RK Mark J. Blair wrote: On Aug 20, 2010, at 11:17 AM, Rick Karlquist wrote: On the 10811 production line, they would use Anzac AMC-123 amplifiers How does this amplifier look for this application? http://minicircuits.com/pdfs/ZFL-500LN.pdf If I understand the specifications properly, the noise figure is better and it has higher reverse isolation and higher gain, but a lower output intercept point. -- Mark J. Blair, NF6Xn...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] Phase noise measurement (was - no subject)
dk...@arcor.de wrote: to drive a +17 dBm mixer, and then amplify the IF output with a low noise current amplifier like the Linear LT1028. You can easily homebrew low noise _voltage_ ? 73, Gerhard dk4xp Oh yes, low noise voltage. The noise current of the LT1028 is actually quite high, but that's OK because the source impedance is low. Rick N6RK ___ 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] Phase noise measurement (was - no subject)
Mark J. Blair wrote: On Aug 20, 2010, at 2:19 PM, Rick Karlquist wrote: It is good that you asked this FAQ. Basically, what is magic about the AMC-123 is that it has certifiably low phase noise, guaranteed by design and characterization, although not specified by Anzac. [...] Having a low noise figure is necessary but not sufficient to have good phase noise. Ah, I see. Is the AMC-123 or an equivalent still in production, or was homebrewing brought up as an option because it's not? -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. It might still be available through Tyco/MAcom. They have continued to make selected Anzac components. There was also an AM-123, which was a TO-something can version. Rick N6RK ___ 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] Phase noise measurement (was - no subject)
Would anyone else like to suggest a known good low phase noise buffer amplifier? Maybe something from a Fred Walls paper? You can always build HF isolation amps by rigging MMICs and attenuators together, but this will not reliably get you below -160 dBc/Hz. Bruce G. has given some good advice in this regard, with some circuit designs at http://www.ko4bb.com/~bruce/IsolationAmplifiers.html and elsewhere. I'm a fan of this version (also from Bruce): http://www.ke5fx.com/norton.htm This one has the advantage of simplicity. No weird parts, nothing that is likely to be out of production or hard to find, and dirt cheap. I've measured the broadband floor at near -170 dBc/Hz at 10 MHz, and its noise contribution at 100 Hz is below what the 3048A can see. These figures are adequate to measure any 10811-class OCXOs. A practical PN measurement system for 10811-class oscillators can be made by building two of those amplifiers and using them to drive pretty much any random double-balanced mixer found on eBay with +10 dBm LO specs or more. Both ports should be driven strongly to reject AM artifacts and avoid degrading the excellent noise floor offered by the amps. I'd hit the LO port with +10 to +12 dBm and the RF port with at least 0 dBm. Then, see the Wenzel app note here ( http://www.wenzel.com/documents/measuringphasenoise.htm ) to lock the two oscillators in quadrature and amplify the resulting baseband output. Any of several sound-card FFT programs can be used to generate an output graph, although if you want absolute calibration in dBc/Hz you need to be prepared to sweep the actual test setup from mixer output to FFT input to watch for various sources of flatness error. A combination of an AD7760-EVAL board and a Digilent Nexys2 can be used to construct an excellent baseband digitizer for the DC-1 MHz spectrum, but most of the time a good-quality 192-kHz sound card is fine for this sort of work. Most good crystal oscillators reach their broadband floor by 10 kHz, so there's no real need to go out to 1 MHz or more. -- john, KE5FX ___ 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] Phase noise measurement (was - no subject)
you have the following options: - HP (Agilent) E5052A/B or RS FSUP Signal Source Analyzer (works for a single DUT, though limited to 1 Hz offset, normally useful for 10 Hz up to 40 MHz). - Compare two identical DUT's with a HP 3048A or similar PN test system and subtract 3 dB, assuming that the PN characteristic of both DUT's is identical. - Compare 3 similar DUT's with a HP 3048A and calculate the individual PN using the three cornerd hat method. - set up a cross correlation PN measurement system similar to the E5052A and have fun. You will however need two - as good as possible, but preferaby not more than 10 dB worse than what you want to measure - VCXO's like HP 10811A's... - you may build your own HP 3048A alike system, but be prepared to invest serious money and time, and much more time than you thought in the beginning... (if that is what you're after, you'll have the most fun you can). - find someone who has one of the above and talk him into measuring yours. Also, it looks like you (Mark) are only about an hour from Cerritos, where the MUD ( http://www.microwaveupdate.org ) conference will be held at the end of October. This could be one option for you. As part of the $35 registration cost, you get access to a test lab set up to help attendees measure noise figure, PN, etc. on any homebrew or commercial gear they wish to bring. Microwave communication nuts are especially concerned with reference-oscillator PN because they end up multiplying it by 1000x or more. Last year Agilent provided an E5052B, and I imagine they will this year, too. If not I'll probably bring my prototype cross-correlation analyzer, so one way or another you would be able to get some PN readings at the conference. -- john, KE5FX ___ 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.
