Re: [time-nuts] HP10514B Mixer Terminations
Jim Lux wrote: On 9/9/12 9:37 PM, li...@lazygranch.com wrote: What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. I think it's where the diode is fully conducting, and into the linear part of the V/I curve, not in the square law part any more. In normal use the LO port is driven hard enough that the mixer is (hopefully) acting as a switch (and RF port is -10dB relative to the LO) ___ Not quite, its when the LO input is large enough to switch the diodes and the RF level is comparable to the LO level.. If the IF output level (for a fixed LO level) is plotted against the RF input level, the curve exhibits a knee and the IF output level saturates at a fixed level when the Rf input level is sufficiently large. At low signal levels the IF output signal level is a proportional to the RF input level at high Rf input levels the IF output level approaches a limiting value. 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] HP10514B Mixer Terminations
On 09/ 9/12 09:03 PM, Bruce Griffiths wrote: For this particular application a capacitive termination (NIST used such a termination in their DMTDs) of the IF port followed by a low pass filter is advantageous. For precision work screw connectors (SMA, TNC, N etc) are more stable than bayonet connectors like the BNC. Bruce I'd agree with Bruce there. I'd chose SMA or N any day over BNC. My favorite connector is APC-7, but you don't see that except on high-end test equipment, and even there it is being phased out in preference to 3.5 mm, which will mate with SMA - although care is needed if mating 3.5 mm to SMA. The only issue with SMA is that you ideally need a torque wrench to tighten them properly. If you don't have one, hand-tight plus 25% of a turn will get you somewhere around the right torque, but I always use a torque wrench myself for permanent connections or temporary ones at microwave frequencies. Dave J. Forster wrote: Most all of this kinda stuff is built using 50 Ohm 'building blocks'. You can almost plug them together like Legos. The HP 10514A is no different: http://www.ko4bb.com/Manuals/HP_Agilent/HP_10514_Mixer_Jan_1967.pdf Mini-Circuits (among others) sells loads of different wsuch components. Your biggest choice may be the connector style. BNC and SMA are very common. If size/weight are not a consideration go BNC. -John === Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ 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. -- Dr. David Kirkby Ph.D C.Eng MIET ___ 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] HP10514B Mixer Terminations
Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ 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] HP10514B Mixer Terminations
Most all of this kinda stuff is built using 50 Ohm 'building blocks'. You can almost plug them together like Legos. The HP 10514A is no different: http://www.ko4bb.com/Manuals/HP_Agilent/HP_10514_Mixer_Jan_1967.pdf Mini-Circuits (among others) sells loads of different wsuch components. Your biggest choice may be the connector style. BNC and SMA are very common. If size/weight are not a consideration go BNC. -John === Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ 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] HP10514B Mixer Terminations
For this particular application a capacitive termination (NIST used such a termination in their DMTDs) of the IF port followed by a low pass filter is advantageous. For precision work screw connectors (SMA, TNC, N etc) are more stable than bayonet connectors like the BNC. Bruce J. Forster wrote: Most all of this kinda stuff is built using 50 Ohm 'building blocks'. You can almost plug them together like Legos. The HP 10514A is no different: http://www.ko4bb.com/Manuals/HP_Agilent/HP_10514_Mixer_Jan_1967.pdf Mini-Circuits (among others) sells loads of different wsuch components. Your biggest choice may be the connector style. BNC and SMA are very common. If size/weight are not a consideration go BNC. -John === Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ 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] HP10514B Mixer Terminations
On 9 September 2012 18:28, Pascual Arbona p.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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] HP10514B Mixer Terminations
David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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] HP10514B Mixer Terminations
Bruce is correct. For best RF performance in an rf environment the use of 50ohms for all ports is a good start. However, even in RF designs you can often optimise a mixer spec with something other than 50 ohms. With a VLF IF freq like a DMTD, each mixer model might have an ideal termination impedance. Steve Mass' book on RF mixers is good for typical mixer applications but the NIST papers are better for DMTD uses. In the mm-wave work I have done, the first place to start is to increase LO power until the s11 of the IF port starts to look like a good match for the IF pre-amp. So each application of a mixer can often be based around what you are doing with it. Each time I use one, I learn a new fact! :-). Great hobby! -Brian, WA1ZMS/4 On Sep 9, 2012, at 4:41 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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] HP10514B Mixer Terminations
Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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] HP10514B Mixer Terminations
NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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 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] HP10514B Mixer Terminations
In the late 60s I built a VLF upconverter using a ring mixer. I tried a few different devices for the diodes. The base/collector junctions of germanium switching transistors gave the best results. On 09/09/2012 03:21 PM, Bruce Griffiths wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] HP10514B Mixer Terminations
On 09/10/2012 12:21 AM, Bruce Griffiths wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. That actually relates back to Craig Nelson hacking audio gear. He was really friendly and we had a nice chat about it. Read more here: http://tf.boulder.nist.gov/general/pdf/2556.pdf http://tf.boulder.nist.gov/general/pdf/2625.pdf http://www.nist.gov/customcf/get_pdf.cfm?pub_id=908622 Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP10514B Mixer Terminations
Hi ….. and of course, once you go into saturation the mixer doesn't look much like 50 ohms any more. Sort of gets us back to terminations again. Bob On Sep 9, 2012, at 6:21 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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 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] HP10514B Mixer Terminations
What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. -Original Message- From: Bob Camp li...@rtty.us Sender: time-nuts-boun...@febo.com Date: Sun, 9 Sep 2012 19:16:22 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] HP10514B Mixer Terminations Hi ….. and of course, once you go into saturation the mixer doesn't look much like 50 ohms any more. Sort of gets us back to terminations again. Bob On Sep 9, 2012, at 6:21 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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 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] HP10514B Mixer Terminations
Not transistor saturation but mixer saturation where the RF input is sufficiently that for a given LO level the IF output level is saturated (ie doesnt increase (or increases very slowly) with increasing RF signal level). Bruce li...@lazygranch.com wrote: What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. -Original Message- From: Bob Campli...@rtty.us Sender: time-nuts-boun...@febo.com Date: Sun, 9 Sep 2012 19:16:22 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] HP10514B Mixer Terminations Hi ….. and of course, once you go into saturation the mixer doesn't look much like 50 ohms any more. Sort of gets us back to terminations again. Bob On Sep 9, 2012, at 6:21 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.comwrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. Dave ___ 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. 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 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
Re: [time-nuts] HP10514B Mixer Terminations
On 9/9/12 9:37 PM, li...@lazygranch.com wrote: What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. I think it's where the diode is fully conducting, and into the linear part of the V/I curve, not in the square law part any more. In normal use the LO port is driven hard enough that the mixer is (hopefully) acting as a switch (and RF port is -10dB relative to the LO) ___ 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] HP10514B Mixer Terminations
Good morning Brian. What do you use as an OFF SET oscillator? Thank you Bert Kehren Miami In a message dated 3/29/2010 11:31:15 P.M. Eastern Daylight Time, kilodelta4foxm...@gmail.com writes: Your correct - your also keeping me up past my bedtime !- I got to be 90 miles from home tomorrow morning by 7:30 AM It looks like I got the squarest wave at 150 pF. Lesser capacitance, give a peaked sinewave, like maybe a second harmonic. Past 200 pF, it starts rounding. 150pf= XC of 53 ohms This DMTD system, will only go to 100 hertz maximum beat for my design... The scope is set to 100 mV per div, 1ms per division, I intentionally mis-triggered it to show rise and fall times. 100 hz beat signal. ANd Bruce told me how to calculate slew rate, but it has to be beated in my thick tough head. And Bruce, I'll try some coax tomorrow, if I get back home early enough - my work project may keep me late. And I plan to only use this system to 100 hertz beat, I was just playing around at 1K.I like learning. Good night.BrianKD4FM Bob Camp wrote: Hi You can get a *much* more squared output from the mixer than the photos you show on the scope. The waveform looks a lit like a triangle wave with the tips chopped off. Normally the fastest edge happens into a capacitive load at RF that's below about 0.5 J ohms for a 50 ohm mixer. Bob On Mar 29, 2010, at 10:06 PM, Brian Kirby wrote: I have been working on a Dual-Mixer Time Difference system. In the first design type/experiment, I was using HP10514B mixers and a LT1037 preamp and a OP27 zero crossing amplifier/limiter - all a very basic setup. I obtained some fair measurements; Using 10 MHz sources, a 9. MHz offset for a 100 hertz beat, the floor of the system looked like this: 0.01 second = 1x10-10 0.1 second = 1x10-11 1 second = 1x10-12 10 second = 1x10-13 100 second = 1x10-14 1000 second = 1x10-15 10,000 second = 1x10-16 this was three days of data Running it again, with a 10 hertz beat; it looked like this; 0.1 second = 4x10-12 1 second = 4x10-13 10 second = 4x10-14 100 second = 4x10-15 1000 second = 4x10-16 I also had a lot of good suggestions From Ulrich Bangert, Bob Camp and Bruce Griffins, who I will call my mentors and thank for all the help. I went back and did some basic experiments this evening. Looking at mixer terminations. I have attached two photos - low res. The first photo named mixer_10db, is the mixer driven with +10 dbm on both ports. The o'scope is looking thru a basic RC filter of 1 kilo-ohm resistor in series with the mixer output, and on the output of the resistor is a 0.1 uF capacitor to ground. This is a mixer that is intentionally over driven to use as a phase detector. The mixer is rated +13 dbm maximum, and about everybody I have talked with (NIST and BIPM) about these mixers ran them at +10 dbm on both LO and RF ports. As these mixers are hard to find, and they are not made anymore, I would not over-drive them any further. These mixers also have some of the lowest phase noise measurements on record. The second photo named mixer_330 pF, is the same setup, except I have put a 330 pF capacitor across the mixer output. By capacitive terminating the mixer, it squares up the output of the mixer - which makes it easier to be converted to a high slew rate signal. What I found, is you want to run the minimum capacitance value for the highest beat frequency you plan to run. That way the signal stays squared up from the highest to the lowest beat frequency. I got this value by playing around by looking at the mixer filtered (RC) output at 1 hz, 10 hz, and 100 hz. When I was using 0.1 and 1 uF terminations, The 1 and 10 hertz beat was OK, but the 100 hertz beat was still a sine wave. That may be why the results above shows a difference. For a test, at 330 pF, I did try it at 1 KHz, it was back to a sine wave. So 330 pF looks good for trying to get a squared wave out of the mixer for 1, 10 and 100 hertz beats.I tried 36 pF for 1 KHz, it did not present enough capacitance to give the squared wave at 1, 10 and 100 hertz beat. We have been running email outside of Time-Nuts group as I am not sure if any of you wanted to see the project I am working on. I did not want to clutter up the forum..but if there is an interest, I can bring it back. My next plans are to start over building a new system using a much lower noise op amp,
Re: [time-nuts] HP10514B Mixer Terminations
Wavetek/Rockland 5120A Synthesizer. ewkeh...@aol.com wrote: Good morning Brian. What do you use as an OFF SET oscillator? Thank you Bert Kehren Miami In a message dated 3/29/2010 11:31:15 P.M. Eastern Daylight Time, kilodelta4foxm...@gmail.com writes: Your correct - your also keeping me up past my bedtime !- I got to be 90 miles from home tomorrow morning by 7:30 AM It looks like I got the squarest wave at 150 pF. Lesser capacitance, give a peaked sinewave, like maybe a second harmonic. Past 200 pF, it starts rounding. 150pf= XC of 53 ohms This DMTD system, will only go to 100 hertz maximum beat for my design... The scope is set to 100 mV per div, 1ms per division, I intentionally mis-triggered it to show rise and fall times. 100 hz beat signal. ANd Bruce told me how to calculate slew rate, but it has to be beated in my thick tough head. And Bruce, I'll try some coax tomorrow, if I get back home early enough - my work project may keep me late. And I plan to only use this system to 100 hertz beat, I was just playing around at 1K.I like learning. Good night.BrianKD4FM Bob Camp wrote: Hi You can get a *much* more squared output from the mixer than the photos you show on the scope. The waveform looks a lit like a triangle wave with the tips chopped off. Normally the fastest edge happens into a capacitive load at RF that's below about 0.5 J ohms for a 50 ohm mixer. Bob On Mar 29, 2010, at 10:06 PM, Brian Kirby wrote: I have been working on a Dual-Mixer Time Difference system. In the first design type/experiment, I was using HP10514B mixers and a LT1037 preamp and a OP27 zero crossing amplifier/limiter - all a very basic setup. I obtained some fair measurements; Using 10 MHz sources, a 9. MHz offset for a 100 hertz beat, the floor of the system looked like this: 0.01 second = 1x10-10 0.1 second = 1x10-11 1 second = 1x10-12 10 second = 1x10-13 100 second = 1x10-14 1000 second = 1x10-15 10,000 second = 1x10-16 this was three days of data Running it again, with a 10 hertz beat; it looked like this; 0.1 second = 4x10-12 1 second = 4x10-13 10 second = 4x10-14 100 second = 4x10-15 1000 second = 4x10-16 I also had a lot of good suggestions From Ulrich Bangert, Bob Camp and Bruce Griffins, who I will call my mentors and thank for all the help. I went back and did some basic experiments this evening. Looking at mixer terminations. I have attached two photos - low res. The first photo named mixer_10db, is the mixer driven with +10 dbm on both ports. The o'scope is looking thru a basic RC filter of 1 kilo-ohm resistor in series with the mixer output, and on the output of the resistor is a 0.1 uF capacitor to ground. This is a mixer that is intentionally over driven to use as a phase detector. The mixer is rated +13 dbm maximum, and about everybody I have talked with (NIST and BIPM) about these mixers ran them at +10 dbm on both LO and RF ports. As these mixers are hard to find, and they are not made anymore, I would not over-drive them any further. These mixers also have some of the lowest phase noise measurements on record. The second photo named mixer_330 pF, is the same setup, except I have put a 330 pF capacitor across the mixer output. By capacitive terminating the mixer, it squares up the output of the mixer - which makes it easier to be converted to a high slew rate signal. What I found, is you want to run the minimum capacitance value for the highest beat frequency you plan to run. That way the signal stays squared up from the highest to the lowest beat frequency. I got this value by playing around by looking at the mixer filtered (RC) output at 1 hz, 10 hz, and 100 hz. When I was using 0.1 and 1 uF terminations, The 1 and 10 hertz beat was OK, but the 100 hertz beat was still a sine wave. That may be why the results above shows a difference. For a test, at 330 pF, I did try it at 1 KHz, it was back to a sine wave. So 330 pF looks good for trying to get a squared wave out of the mixer for 1, 10 and 100 hertz beats.I tried 36 pF for 1 KHz, it did not present enough capacitance to give the squared wave at 1, 10 and 100 hertz beat. We have been running email outside of Time-Nuts group as I am not sure if any of you wanted to see the project I am working on. I did not want to clutter up the forum..but if there is an interest, I can bring it back. My next plans are to start
Re: [time-nuts] HP10514B Mixer Terminations
Hi If you are just changing C1 when you go to 150 pf, the mixer is still pretty heavily loaded by R1 and C2. The mixer is only close to open circuit with R1 (or R1 plus a coil) at 500 ohms. Bob On Mar 30, 2010, at 7:55 PM, Brian Kirby wrote: Here's a block/schematic of the last version I reported on last night. Brian Kirby - KD4FM - Guntersville, Alabama ewkeh...@aol.com wrote: Good morning Brian. What do you use as an OFF SET oscillator? Thank you Bert Kehren Miami . HP_DMTD_23MAR2010.pdf___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP10514B Mixer Terminations
That post had the drawing of the last system (2nd generation), just to show the setup I was using for the offset generator. (LT1027 preamp). The new system, which I was testing the mixer terminations, has the LT1028. Its terminated in 150 pF, a 1 kilo-ohm series resistor and then a 0.1 uF capacitor, then the scope probe. The LT1028 is disconnected an unpowered for these test. I tried something this evening, I used some trimmer capacitors and I got best square wave at 156 pFxC at 20 mhz = 51.0 ohmsinteresting. I'm beat and I got to go back to Talladega tomorrow morning, so I'm not going do any more experiments this evening. Brian Bob Camp wrote: Hi If you are just changing C1 when you go to 150 pf, the mixer is still pretty heavily loaded by R1 and C2. The mixer is only close to open circuit with R1 (or R1 plus a coil) at 500 ohms. Bob On Mar 30, 2010, at 7:55 PM, Brian Kirby wrote: Here's a block/schematic of the last version I reported on last night. Brian Kirby - KD4FM - Guntersville, Alabama ewkeh...@aol.com wrote: Good morning Brian. What do you use as an OFF SET oscillator? Thank you Bert Kehren Miami . HP_DMTD_23MAR2010.pdf___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] HP10514B Mixer Terminations
Hi You can get a *much* more squared output from the mixer than the photos you show on the scope. The waveform looks a lit like a triangle wave with the tips chopped off. Normally the fastest edge happens into a capacitive load at RF that's below about 0.5 J ohms for a 50 ohm mixer. Bob On Mar 29, 2010, at 10:06 PM, Brian Kirby wrote: I have been working on a Dual-Mixer Time Difference system. In the first design type/experiment, I was using HP10514B mixers and a LT1037 preamp and a OP27 zero crossing amplifier/limiter - all a very basic setup. I obtained some fair measurements; Using 10 MHz sources, a 9. MHz offset for a 100 hertz beat, the floor of the system looked like this: 0.01 second = 1x10-10 0.1 second = 1x10-11 1 second = 1x10-12 10 second = 1x10-13 100 second = 1x10-14 1000 second = 1x10-15 10,000 second = 1x10-16 this was three days of data Running it again, with a 10 hertz beat; it looked like this; 0.1 second = 4x10-12 1 second = 4x10-13 10 second = 4x10-14 100 second = 4x10-15 1000 second = 4x10-16 I also had a lot of good suggestions From Ulrich Bangert, Bob Camp and Bruce Griffins, who I will call my mentors and thank for all the help. I went back and did some basic experiments this evening. Looking at mixer terminations. I have attached two photos - low res. The first photo named mixer_10db, is the mixer driven with +10 dbm on both ports. The o'scope is looking thru a basic RC filter of 1 kilo-ohm resistor in series with the mixer output, and on the output of the resistor is a 0.1 uF capacitor to ground. This is a mixer that is intentionally over driven to use as a phase detector. The mixer is rated +13 dbm maximum, and about everybody I have talked with (NIST and BIPM) about these mixers ran them at +10 dbm on both LO and RF ports. As these mixers are hard to find, and they are not made anymore, I would not over-drive them any further. These mixers also have some of the lowest phase noise measurements on record. The second photo named mixer_330 pF, is the same setup, except I have put a 330 pF capacitor across the mixer output. By capacitive terminating the mixer, it squares up the output of the mixer - which makes it easier to be converted to a high slew rate signal. What I found, is you want to run the minimum capacitance value for the highest beat frequency you plan to run. That way the signal stays squared up from the highest to the lowest beat frequency. I got this value by playing around by looking at the mixer filtered (RC) output at 1 hz, 10 hz, and 100 hz. When I was using 0.1 and 1 uF terminations, The 1 and 10 hertz beat was OK, but the 100 hertz beat was still a sine wave. That may be why the results above shows a difference. For a test, at 330 pF, I did try it at 1 KHz, it was back to a sine wave. So 330 pF looks good for trying to get a squared wave out of the mixer for 1, 10 and 100 hertz beats.I tried 36 pF for 1 KHz, it did not present enough capacitance to give the squared wave at 1, 10 and 100 hertz beat. We have been running email outside of Time-Nuts group as I am not sure if any of you wanted to see the project I am working on. I did not want to clutter up the forum..but if there is an interest, I can bring it back. My next plans are to start over building a new system using a much lower noise op amp, the LT1028. If the mixer terminations are OK with my mentors, I will use a LT1028 preamp set for about x15 gain and it will dump into the first set of limiter diodes. And I believe that will call for 1.6 KHz low pass filtering on the first limiter diodes. Comments ? Brian - KD4FM mixer_330pf.jpgmixer_10dbm.jpg___ 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] HP10514B Mixer Terminations
Brian You should get even better results if you replace the 330pF cap with a 1/4 wave (at the 20MHz sum frequency) coax cable open circuited stub. Thats around 2.5m of RG 58 coax for example. Connecting a series tuned circuit (at the sum frequency) across the mixer IF output should also work well. Bruce Brian Kirby wrote: I have been working on a Dual-Mixer Time Difference system. In the first design type/experiment, I was using HP10514B mixers and a LT1037 preamp and a OP27 zero crossing amplifier/limiter - all a very basic setup. I obtained some fair measurements; Using 10 MHz sources, a 9. MHz offset for a 100 hertz beat, the floor of the system looked like this: 0.01 second = 1x10-10 0.1 second = 1x10-11 1 second = 1x10-12 10 second = 1x10-13 100 second = 1x10-14 1000 second = 1x10-15 10,000 second = 1x10-16 this was three days of data Running it again, with a 10 hertz beat; it looked like this; 0.1 second = 4x10-12 1 second = 4x10-13 10 second = 4x10-14 100 second = 4x10-15 1000 second = 4x10-16 I also had a lot of good suggestions From Ulrich Bangert, Bob Camp and Bruce Griffins, who I will call my mentors and thank for all the help. I went back and did some basic experiments this evening. Looking at mixer terminations. I have attached two photos - low res. The first photo named mixer_10db, is the mixer driven with +10 dbm on both ports. The o'scope is looking thru a basic RC filter of 1 kilo-ohm resistor in series with the mixer output, and on the output of the resistor is a 0.1 uF capacitor to ground. This is a mixer that is intentionally over driven to use as a phase detector. The mixer is rated +13 dbm maximum, and about everybody I have talked with (NIST and BIPM) about these mixers ran them at +10 dbm on both LO and RF ports. As these mixers are hard to find, and they are not made anymore, I would not over-drive them any further. These mixers also have some of the lowest phase noise measurements on record. The second photo named mixer_330 pF, is the same setup, except I have put a 330 pF capacitor across the mixer output. By capacitive terminating the mixer, it squares up the output of the mixer - which makes it easier to be converted to a high slew rate signal. What I found, is you want to run the minimum capacitance value for the highest beat frequency you plan to run. That way the signal stays squared up from the highest to the lowest beat frequency. I got this value by playing around by looking at the mixer filtered (RC) output at 1 hz, 10 hz, and 100 hz. When I was using 0.1 and 1 uF terminations, The 1 and 10 hertz beat was OK, but the 100 hertz beat was still a sine wave. That may be why the results above shows a difference. For a test, at 330 pF, I did try it at 1 KHz, it was back to a sine wave. So 330 pF looks good for trying to get a squared wave out of the mixer for 1, 10 and 100 hertz beats.I tried 36 pF for 1 KHz, it did not present enough capacitance to give the squared wave at 1, 10 and 100 hertz beat. We have been running email outside of Time-Nuts group as I am not sure if any of you wanted to see the project I am working on. I did not want to clutter up the forum..but if there is an interest, I can bring it back. My next plans are to start over building a new system using a much lower noise op amp, the LT1028. If the mixer terminations are OK with my mentors, I will use a LT1028 preamp set for about x15 gain and it will dump into the first set of limiter diodes. And I believe that will call for 1.6 KHz low pass filtering on the first limiter diodes. Comments ? Brian - KD4FM ___ 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] HP10514B Mixer Terminations
Your poor results at 1kHz have more to do with the 1K +0.1uF low pass filter which has a cutoff frequency of about 1.6KHz. This will attenuate the beat frequency harmonics required for high slew rate at the beat frequency zero crossings. A filter cutoff of 16kHz (1K + 10nF) should improve the slew rate at 1KHz. Bruce Brian Kirby wrote: I have been working on a Dual-Mixer Time Difference system. In the first design type/experiment, I was using HP10514B mixers and a LT1037 preamp and a OP27 zero crossing amplifier/limiter - all a very basic setup. I obtained some fair measurements; Using 10 MHz sources, a 9. MHz offset for a 100 hertz beat, the floor of the system looked like this: 0.01 second = 1x10-10 0.1 second = 1x10-11 1 second = 1x10-12 10 second = 1x10-13 100 second = 1x10-14 1000 second = 1x10-15 10,000 second = 1x10-16 this was three days of data Running it again, with a 10 hertz beat; it looked like this; 0.1 second = 4x10-12 1 second = 4x10-13 10 second = 4x10-14 100 second = 4x10-15 1000 second = 4x10-16 I also had a lot of good suggestions From Ulrich Bangert, Bob Camp and Bruce Griffins, who I will call my mentors and thank for all the help. I went back and did some basic experiments this evening. Looking at mixer terminations. I have attached two photos - low res. The first photo named mixer_10db, is the mixer driven with +10 dbm on both ports. The o'scope is looking thru a basic RC filter of 1 kilo-ohm resistor in series with the mixer output, and on the output of the resistor is a 0.1 uF capacitor to ground. This is a mixer that is intentionally over driven to use as a phase detector. The mixer is rated +13 dbm maximum, and about everybody I have talked with (NIST and BIPM) about these mixers ran them at +10 dbm on both LO and RF ports. As these mixers are hard to find, and they are not made anymore, I would not over-drive them any further. These mixers also have some of the lowest phase noise measurements on record. The second photo named mixer_330 pF, is the same setup, except I have put a 330 pF capacitor across the mixer output. By capacitive terminating the mixer, it squares up the output of the mixer - which makes it easier to be converted to a high slew rate signal. What I found, is you want to run the minimum capacitance value for the highest beat frequency you plan to run. That way the signal stays squared up from the highest to the lowest beat frequency. I got this value by playing around by looking at the mixer filtered (RC) output at 1 hz, 10 hz, and 100 hz. When I was using 0.1 and 1 uF terminations, The 1 and 10 hertz beat was OK, but the 100 hertz beat was still a sine wave. That may be why the results above shows a difference. For a test, at 330 pF, I did try it at 1 KHz, it was back to a sine wave. So 330 pF looks good for trying to get a squared wave out of the mixer for 1, 10 and 100 hertz beats.I tried 36 pF for 1 KHz, it did not present enough capacitance to give the squared wave at 1, 10 and 100 hertz beat. We have been running email outside of Time-Nuts group as I am not sure if any of you wanted to see the project I am working on. I did not want to clutter up the forum..but if there is an interest, I can bring it back. My next plans are to start over building a new system using a much lower noise op amp, the LT1028. If the mixer terminations are OK with my mentors, I will use a LT1028 preamp set for about x15 gain and it will dump into the first set of limiter diodes. And I believe that will call for 1.6 KHz low pass filtering on the first limiter diodes. Comments ? Brian - KD4FM ___ 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] HP10514B Mixer Terminations
Your correct - your also keeping me up past my bedtime !- I got to be 90 miles from home tomorrow morning by 7:30 AM It looks like I got the squarest wave at 150 pF. Lesser capacitance, give a peaked sinewave, like maybe a second harmonic. Past 200 pF, it starts rounding. 150pf= XC of 53 ohms This DMTD system, will only go to 100 hertz maximum beat for my design... The scope is set to 100 mV per div, 1ms per division, I intentionally mis-triggered it to show rise and fall times. 100 hz beat signal. ANd Bruce told me how to calculate slew rate, but it has to be beated in my thick tough head. And Bruce, I'll try some coax tomorrow, if I get back home early enough - my work project may keep me late. And I plan to only use this system to 100 hertz beat, I was just playing around at 1K.I like learning. Good night.BrianKD4FM Bob Camp wrote: Hi You can get a *much* more squared output from the mixer than the photos you show on the scope. The waveform looks a lit like a triangle wave with the tips chopped off. Normally the fastest edge happens into a capacitive load at RF that's below about 0.5 J ohms for a 50 ohm mixer. Bob On Mar 29, 2010, at 10:06 PM, Brian Kirby wrote: I have been working on a Dual-Mixer Time Difference system. In the first design type/experiment, I was using HP10514B mixers and a LT1037 preamp and a OP27 zero crossing amplifier/limiter - all a very basic setup. I obtained some fair measurements; Using 10 MHz sources, a 9. MHz offset for a 100 hertz beat, the floor of the system looked like this: 0.01 second = 1x10-10 0.1 second = 1x10-11 1 second = 1x10-12 10 second = 1x10-13 100 second = 1x10-14 1000 second = 1x10-15 10,000 second = 1x10-16 this was three days of data Running it again, with a 10 hertz beat; it looked like this; 0.1 second = 4x10-12 1 second = 4x10-13 10 second = 4x10-14 100 second = 4x10-15 1000 second = 4x10-16 I also had a lot of good suggestions From Ulrich Bangert, Bob Camp and Bruce Griffins, who I will call my mentors and thank for all the help. I went back and did some basic experiments this evening. Looking at mixer terminations. I have attached two photos - low res. The first photo named mixer_10db, is the mixer driven with +10 dbm on both ports. The o'scope is looking thru a basic RC filter of 1 kilo-ohm resistor in series with the mixer output, and on the output of the resistor is a 0.1 uF capacitor to ground. This is a mixer that is intentionally over driven to use as a phase detector. The mixer is rated +13 dbm maximum, and about everybody I have talked with (NIST and BIPM) about these mixers ran them at +10 dbm on both LO and RF ports. As these mixers are hard to find, and they are not made anymore, I would not over-drive them any further. These mixers also have some of the lowest phase noise measurements on record. The second photo named mixer_330 pF, is the same setup, except I have put a 330 pF capacitor across the mixer output. By capacitive terminating the mixer, it squares up the output of the mixer - which makes it easier to be converted to a high slew rate signal. What I found, is you want to run the minimum capacitance value for the highest beat frequency you plan to run. That way the signal stays squared up from the highest to the lowest beat frequency. I got this value by playing around by looking at the mixer filtered (RC) output at 1 hz, 10 hz, and 100 hz. When I was using 0.1 and 1 uF terminations, The 1 and 10 hertz beat was OK, but the 100 hertz beat was still a sine wave. That may be why the results above shows a difference. For a test, at 330 pF, I did try it at 1 KHz, it was back to a sine wave. So 330 pF looks good for trying to get a squared wave out of the mixer for 1, 10 and 100 hertz beats.I tried 36 pF for 1 KHz, it did not present enough capacitance to give the squared wave at 1, 10 and 100 hertz beat. We have been running email outside of Time-Nuts group as I am not sure if any of you wanted to see the project I am working on. I did not want to clutter up the forum..but if there is an interest, I can bring it back. My next plans are to start over building a new system using a much lower noise op amp, the LT1028. If the mixer terminations are OK with my mentors, I will use a LT1028 preamp set for about x15 gain and it will dump into the first set of limiter diodes. And I believe that will call for 1.6 KHz low pass filtering on the first limiter diodes. Comments ? Brian - KD4FM mixer_330pf.jpgmixer_10dbm.jpg___ 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
