Re: [time-nuts] fast edge, rise time.
Paul It weighs 30 lbs. Pictures are on face book or I can email with an address. Bill -Original Message- From: paul swed Sent: Wednesday, January 15, 2014 12:20 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Bill Interesting and curious what does it weigh? I would guess since its NIST a lot. Regards Paul WB8TSL On Wed, Jan 15, 2014 at 1:15 PM, Bill Reed br...@otelco.net wrote: Thanks Mark I must have serial number 2 of that series of IPG's. The one in the article is SN-3-75-1 and mine is SN-3-75-2. It was probably fabricated in March 75. I plan on visiting Redstone library to look up references 8 and 9. Bill -Original Message- From: Mark Kahrs Sent: Tuesday, January 14, 2014 12:02 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. You might be interested to know this was discussed in a paper by Jim Andrews (founder of Picosecond Pulse Laboratories): http://www.nist.gov/calibrations/upload/im-25-4.pdf From the age of the paper, I'd say this generator is probably more than 40 years young. On Mon, Jan 13, 2014 at 2:22 PM, Bill Reed br...@otelco.net wrote: Hi, Since there is no interest in my pulse generator maybe one of you knows someone at NBS who can provide a schematic of the generator. It has NBS Impulse Generator SN 3-75-2 engraved on the front panel and is ~ 10 x 16 x 17. Thanks, Bill Reed -Original Message- From: Bill Reed Sent: Tuesday, January 07, 2014 7:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Hi, Since you guys are interested in fast pule generators, I have one you may be interested in. I got it in govt. auction about 25 years ago for ~ $ 50.00. I will sell it to anyone for $ 50.00 plus shipping. I prefer to sell to someone who will restore and use it rather than parting it. It has more than $ 50.00 parts in it. There are a 30 turn 6.5 inch diameter hard line, wide band hybrid coupler, diode assembly and several adapters and attenuators. I believe the hard line discharges into a step diode. The power supply includes 200 V plus other voltages. If I remember correctly ( I have no high speed scope now ) the pulse is 2 nanoseconds wide with a 280 picosecond rise time and and 2.5 Vpp. I checked with a 200 MHz digital scope and can see a pulse that verifies my scopes bandwidth. The rate generator works but has problems. See facebook (ree...@otelco.net) for pictures under Impulse. Bill Reed256 586-3446 -Original Message- From: ct1dmk Sent: Sunday, December 29, 2013 7:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] fast edge, rise time.
Thanks Mark I must have serial number 2 of that series of IPG's. The one in the article is SN-3-75-1 and mine is SN-3-75-2. It was probably fabricated in March 75. I plan on visiting Redstone library to look up references 8 and 9. Bill -Original Message- From: Mark Kahrs Sent: Tuesday, January 14, 2014 12:02 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. You might be interested to know this was discussed in a paper by Jim Andrews (founder of Picosecond Pulse Laboratories): http://www.nist.gov/calibrations/upload/im-25-4.pdf From the age of the paper, I'd say this generator is probably more than 40 years young. On Mon, Jan 13, 2014 at 2:22 PM, Bill Reed br...@otelco.net wrote: Hi, Since there is no interest in my pulse generator maybe one of you knows someone at NBS who can provide a schematic of the generator. It has NBS Impulse Generator SN 3-75-2 engraved on the front panel and is ~ 10 x 16 x 17. Thanks, Bill Reed -Original Message- From: Bill Reed Sent: Tuesday, January 07, 2014 7:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Hi, Since you guys are interested in fast pule generators, I have one you may be interested in. I got it in govt. auction about 25 years ago for ~ $ 50.00. I will sell it to anyone for $ 50.00 plus shipping. I prefer to sell to someone who will restore and use it rather than parting it. It has more than $ 50.00 parts in it. There are a 30 turn 6.5 inch diameter hard line, wide band hybrid coupler, diode assembly and several adapters and attenuators. I believe the hard line discharges into a step diode. The power supply includes 200 V plus other voltages. If I remember correctly ( I have no high speed scope now ) the pulse is 2 nanoseconds wide with a 280 picosecond rise time and and 2.5 Vpp. I checked with a 200 MHz digital scope and can see a pulse that verifies my scopes bandwidth. The rate generator works but has problems. See facebook (ree...@otelco.net) for pictures under Impulse. Bill Reed256 586-3446 -Original Message- From: ct1dmk Sent: Sunday, December 29, 2013 7:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ 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] fast edge, rise time.
Bill Interesting and curious what does it weigh? I would guess since its NIST a lot. Regards Paul WB8TSL On Wed, Jan 15, 2014 at 1:15 PM, Bill Reed br...@otelco.net wrote: Thanks Mark I must have serial number 2 of that series of IPG's. The one in the article is SN-3-75-1 and mine is SN-3-75-2. It was probably fabricated in March 75. I plan on visiting Redstone library to look up references 8 and 9. Bill -Original Message- From: Mark Kahrs Sent: Tuesday, January 14, 2014 12:02 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. You might be interested to know this was discussed in a paper by Jim Andrews (founder of Picosecond Pulse Laboratories): http://www.nist.gov/calibrations/upload/im-25-4.pdf From the age of the paper, I'd say this generator is probably more than 40 years young. On Mon, Jan 13, 2014 at 2:22 PM, Bill Reed br...@otelco.net wrote: Hi, Since there is no interest in my pulse generator maybe one of you knows someone at NBS who can provide a schematic of the generator. It has NBS Impulse Generator SN 3-75-2 engraved on the front panel and is ~ 10 x 16 x 17. Thanks, Bill Reed -Original Message- From: Bill Reed Sent: Tuesday, January 07, 2014 7:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Hi, Since you guys are interested in fast pule generators, I have one you may be interested in. I got it in govt. auction about 25 years ago for ~ $ 50.00. I will sell it to anyone for $ 50.00 plus shipping. I prefer to sell to someone who will restore and use it rather than parting it. It has more than $ 50.00 parts in it. There are a 30 turn 6.5 inch diameter hard line, wide band hybrid coupler, diode assembly and several adapters and attenuators. I believe the hard line discharges into a step diode. The power supply includes 200 V plus other voltages. If I remember correctly ( I have no high speed scope now ) the pulse is 2 nanoseconds wide with a 280 picosecond rise time and and 2.5 Vpp. I checked with a 200 MHz digital scope and can see a pulse that verifies my scopes bandwidth. The rate generator works but has problems. See facebook (ree...@otelco.net) for pictures under Impulse. Bill Reed256 586-3446 -Original Message- From: ct1dmk Sent: Sunday, December 29, 2013 7:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] fast edge, rise time.
You might be interested to know this was discussed in a paper by Jim Andrews (founder of Picosecond Pulse Laboratories): http://www.nist.gov/calibrations/upload/im-25-4.pdf From the age of the paper, I'd say this generator is probably more than 40 years young. On Mon, Jan 13, 2014 at 2:22 PM, Bill Reed br...@otelco.net wrote: Hi, Since there is no interest in my pulse generator maybe one of you knows someone at NBS who can provide a schematic of the generator. It has NBS Impulse Generator SN 3-75-2 engraved on the front panel and is ~ 10 x 16 x 17. Thanks, Bill Reed -Original Message- From: Bill Reed Sent: Tuesday, January 07, 2014 7:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Hi, Since you guys are interested in fast pule generators, I have one you may be interested in. I got it in govt. auction about 25 years ago for ~ $ 50.00. I will sell it to anyone for $ 50.00 plus shipping. I prefer to sell to someone who will restore and use it rather than parting it. It has more than $ 50.00 parts in it. There are a 30 turn 6.5 inch diameter hard line, wide band hybrid coupler, diode assembly and several adapters and attenuators. I believe the hard line discharges into a step diode. The power supply includes 200 V plus other voltages. If I remember correctly ( I have no high speed scope now ) the pulse is 2 nanoseconds wide with a 280 picosecond rise time and and 2.5 Vpp. I checked with a 200 MHz digital scope and can see a pulse that verifies my scopes bandwidth. The rate generator works but has problems. See facebook (ree...@otelco.net) for pictures under Impulse. Bill Reed256 586-3446 -Original Message- From: ct1dmk Sent: Sunday, December 29, 2013 7:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ 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] fast edge, rise time.
Hi, Since there is no interest in my pulse generator maybe one of you knows someone at NBS who can provide a schematic of the generator. It has NBS Impulse Generator SN 3-75-2 engraved on the front panel and is ~ 10 x 16 x 17. Thanks, Bill Reed -Original Message- From: Bill Reed Sent: Tuesday, January 07, 2014 7:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Hi, Since you guys are interested in fast pule generators, I have one you may be interested in. I got it in govt. auction about 25 years ago for ~ $ 50.00. I will sell it to anyone for $ 50.00 plus shipping. I prefer to sell to someone who will restore and use it rather than parting it. It has more than $ 50.00 parts in it. There are a 30 turn 6.5 inch diameter hard line, wide band hybrid coupler, diode assembly and several adapters and attenuators. I believe the hard line discharges into a step diode. The power supply includes 200 V plus other voltages. If I remember correctly ( I have no high speed scope now ) the pulse is 2 nanoseconds wide with a 280 picosecond rise time and and 2.5 Vpp. I checked with a 200 MHz digital scope and can see a pulse that verifies my scopes bandwidth. The rate generator works but has problems. See facebook (ree...@otelco.net) for pictures under Impulse. Bill Reed256 586-3446 -Original Message- From: ct1dmk Sent: Sunday, December 29, 2013 7:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ 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] fast edge, rise time.
Hi, Since you guys are interested in fast pule generators, I have one you may be interested in. I got it in govt. auction about 25 years ago for ~ $ 50.00. I will sell it to anyone for $ 50.00 plus shipping. I prefer to sell to someone who will restore and use it rather than parting it. It has more than $ 50.00 parts in it. There are a 30 turn 6.5 inch diameter hard line, wide band hybrid coupler, diode assembly and several adapters and attenuators. I believe the hard line discharges into a step diode. The power supply includes 200 V plus other voltages. If I remember correctly ( I have no high speed scope now ) the pulse is 2 nanoseconds wide with a 280 picosecond rise time and and 2.5 Vpp. I checked with a 200 MHz digital scope and can see a pulse that verifies my scopes bandwidth. The rate generator works but has problems. See facebook (ree...@otelco.net) for pictures under Impulse. Bill Reed256 586-3446 -Original Message- From: ct1dmk Sent: Sunday, December 29, 2013 7:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast edge, rise time. Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ 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] fast edge, rise time.
Thank you all for your comments on this subject. Happy new year. Luis Cupido. ct1dmk. ___ 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] fast edge, rise time.
On Fri, 27 Dec 2013 02:16:26 + ct1dmk ct1...@gmail.com wrote: Since the amplitude and timing parameters are to be controlled (pulse timing come from an FPGA) I really need a solution using that trivial switching element fet or bipolar (and can't really do a more exotic scheme if I cant electronically control the parameters) also I must use a transformer because these short pulse are to be superimposed to another voltage and a transformer becomes very handy to do that. I interrupt the wire and insert the secondary there to add the pulses. If you are already using an FPGA, you can use it for pulse forming. Just use some delay line (or two) and an AND gate. This should give you an easily changable pulse from sub-1ns to an aribtrary long pulse. The problem here is that your delay line will not have the same step sizes for each step of the delay line (varies from 10ps to ~100ps on a Virtex-4). [1] gives a small overview of the problem and where it comes from. There are other papers on TDCs that deal with this and might give a solution how to linearize it. Googling for vernier delay line linearization sould give you some results. As output from the FPGA you probably want to use some differntial format, to increase the steepness of the rising/falling edge. When you have the pulse you can use some standard RF amplifier circuit that drivers your transformer. Setting the amplitude should be easy too. Attila Kinali [1] A High Resolution (10 ps RMS) 48-Channel Time-to-Digital Converter (TDC) Implemented in a Field Programmable Gate Array(FPGA), by Bayer and Traxler, 2011 -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] fast edge, rise time.
On Fri, 27 Dec 2013 11:30:00 +0100 Attila Kinali att...@kinali.ch wrote: When you have the pulse you can use some standard RF amplifier circuit that drivers your transformer. Setting the amplitude should be easy too. I just reread your first mail and realized that this amplifier might be your problem. If you use a differntial, current-coupled structure (similar to current mode logic) with GHz RF bipolar transistors, you should be able to get your pulse with good shape into the transformer. Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] fast edge, rise time.
On 12/26/13 8:07 AM, ct1dmk wrote: Hello, I'm willing to generate a pulse (of some few hundred volts) by discharging a capacitor into a pulse transformer I'm solely interested is the active edge (call it either rise or fall depending on the wiring of the output of the transformer). ns risetime pulses sounds like fairly straight forward radar stuff. the inductance of the transformer is going to be your challenge, depending on the energy level. What about a non-transformer alternative? Can you just charge your cap up to the few hundred volts and have a switch that can take the voltage? How much energy do you need? You said a few hundred volts, but is that microjoules, joules, or kilojoules? A small triggered spark gap would be one way. There's also the ever popular krytron, which has very good timing accuracy. YOu might look for circuits used for exploding bridge wires (EBW) The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. You want some sort of RF transistor here. What about one of the new LDMOS FETs: some have fairly impressive voltage handling, and if they work at 1 GHz for radar applications, they will work for you. What about stacking a bunch of MMIC RF amplifiers (e.g. like the ERA or GAL from minicircuits) Other traditional approaches to fast pulse generation are avalanche transistors. There's also a variety of interesting pulse forming networks that can generate fast rise time high voltage pulses. Blumlein arrangements are one. Your 100ns pulse is fairly long for a transmission line scheme, though (20-30 m of coax) ___ 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] fast edge, rise time.
The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. I have seen recently two kinds of devices for similar task: MOSFETs and avalanche breakdown transistors. Try the second ones, might be a good fit if the pulsing is not very frequent (say, kHz range). Regards, Marek ___ 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] fast edge, rise time.
On Thu, 26 Dec 2013 16:07:49 + ct1dmk ct1...@gmail.com wrote: The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. First idea that comes to mind is using a bipolar transistor in avalanche mode. There are specialized transistors for this, like the ZTX415[1,2], but you can use 0-8-15 tranistors like a BC548 as well. If using a general purpose transistor, then the avalanche voltage will vary quite a bit from transistor to transistor. Easiest way to get around this is to use a small resistor from base to emiter to drain any charge generated, then insert a fast rising spike into the base. Using this, you can enter the range of the avalanche voltage while surpressing the effect until you want to trigger it. With this you should be able to get into the low ns range, if not even below 1ns. The limiting factor is usually how fast the base voltage can rise. The avalanche voltage for BC548 in my experiments was in the vincinity of 200V. I took the idea from [3], which contains a description of such a pulse generator with a general purpose transistor on page 32. Almost the same circuit can be found in [4]. Attila Kinali [1] ZTX415 datasheet http://www.diodes.com/datasheets/ZTX415.pdf [2] ZTX415 avalanche mode transistore application note 8, by Neil Chadderton, 1996 http://www.diodes.com/_files/products_appnote_pdfs/zetex/an8.pdf [3] A seven-nanosecond comparator for single supply operation, by Jim Williams, 1998 http://cds.linear.com/docs/Application%20Note/an72f.pdf [4] Slew rate verification for wide band amiplifier, by Jim Williams, 2003 http://cds.linear.com/docs/Application%20Note/an94f.pdf -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] fast edge, rise time.
Hi If you go the Krytron route you probably will need some fairly fancy transformers as well…. Bob On Dec 26, 2013, at 11:19 AM, Jim Lux jim...@earthlink.net wrote: On 12/26/13 8:07 AM, ct1dmk wrote: Hello, I'm willing to generate a pulse (of some few hundred volts) by discharging a capacitor into a pulse transformer I'm solely interested is the active edge (call it either rise or fall depending on the wiring of the output of the transformer). ns risetime pulses sounds like fairly straight forward radar stuff. the inductance of the transformer is going to be your challenge, depending on the energy level. What about a non-transformer alternative? Can you just charge your cap up to the few hundred volts and have a switch that can take the voltage? How much energy do you need? You said a few hundred volts, but is that microjoules, joules, or kilojoules? A small triggered spark gap would be one way. There's also the ever popular krytron, which has very good timing accuracy. YOu might look for circuits used for exploding bridge wires (EBW) The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. You want some sort of RF transistor here. What about one of the new LDMOS FETs: some have fairly impressive voltage handling, and if they work at 1 GHz for radar applications, they will work for you. What about stacking a bunch of MMIC RF amplifiers (e.g. like the ERA or GAL from minicircuits) Other traditional approaches to fast pulse generation are avalanche transistors. There's also a variety of interesting pulse forming networks that can generate fast rise time high voltage pulses. Blumlein arrangements are one. Your 100ns pulse is fairly long for a transmission line scheme, though (20-30 m of coax) ___ 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] fast edge, rise time.
Look at the Jim Williams application note http://cds.linear.com/docs/en/application-note/an47fa.pdf Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ct1dmk Sent: 26 December 2013 16:08 To: Discussion of precise time and frequency measurement Subject: [time-nuts] fast edge, rise time. Hello, I'm willing to generate a pulse (of some few hundred volts) by discharging a capacitor into a pulse transformer I'm solely interested is the active edge (call it either rise or fall depending on the wiring of the output of the transformer). The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. I would be happy to receive some comments/ideas that may pop out of your heads. Thanks. hope that my quest for fast rise time is not too off topic on this time list... but... there are so many experts on this list that I could not resist ;-) Luis Cupido ct1dmk. p.s. ( I switch a capacitor to GND with a transistor (fet or bipolar). that capacitor has a charging resistor to 48V, transformer has a 9:1 voltage ratio. Pulse average power is quite low a few watt only. At the primary side some 20A of peak current for less than 100ns... and very low duty cycle. ) ___ 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] fast edge, rise time.
On 26 December 2013 16:07, ct1dmk ct1...@gmail.com wrote: Hello, I'm willing to generate a pulse (of some few hundred volts) by discharging a capacitor into a pulse transformer There are probably more modern approaches, but a thryatron is one possibility. Shame I put on in the dump a few months ago. Maybe though they are more suitable for higher voltages. 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] fast edge, rise time.
Can you say more about your application? What does your load look like? What pulse shape? There are well-known solutiuons for most problems. As Jim said, a lot depends on the energy you need per pulse. What works for a few mJ will not work for MJ BTW, SCRs probably switch a lot faster than thyratrons. Years ago, I cobbled up a high-current SCR pulser with a few thousand uF cap and stud mounted SCR. It would drive enough current through a length of hook up wire so that the wire would jump off the desk when pulsed. -John = On 26 December 2013 16:07, ct1dmk ct1...@gmail.com wrote: Hello, I'm willing to generate a pulse (of some few hundred volts) by discharging a capacitor into a pulse transformer There are probably more modern approaches, but a thryatron is one possibility. Shame I put on in the dump a few months ago. Maybe though they are more suitable for higher voltages. 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. ___ 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] fast edge, rise time.
Years ago I had a cousin who ran a civilian calibration lab. For calibrating scopes, etc, for rise time he used a mercury wetted relay which he claimed had nearly instant rise time and no bounce. Seems that he used a resistive divider and the mercury relay shunted a portion of the divider. With very small inductances and capacitance to slow things down it would seem to be very fast. Al, k9si, retired The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. I would be happy to receive some comments/ideas that may pop out of your heads. Thanks. ___ 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] fast edge, rise time.
There are very fast pulsers, some in NIM, that use a charged coax line and Hg relay to calibrate Pulse Height analyzers. The line length sets the pulse length; the charging voltage, the pulse height. -John Years ago I had a cousin who ran a civilian calibration lab. For calibrating scopes, etc, for rise time he used a mercury wetted relay which he claimed had nearly instant rise time and no bounce. Seems that he used a resistive divider and the mercury relay shunted a portion of the divider. With very small inductances and capacitance to slow things down it would seem to be very fast. Al, k9si, retired The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. I would be happy to receive some comments/ideas that may pop out of your heads. Thanks. ___ 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] fast edge, rise time.
On Thu, 26 Dec 2013 16:07:49 +, ct1dmk wrote: The target is 4ns, while ideas seemed to be clear at some point, now I'm having doubts if better to use a MOSFET or a bipolar transistor as the switch element. Experiments with MOSFETs presented me some difficulties charging the gate capacitance having some trouble to achieve something in the 4ns region. Well 4ns seems hard whatever device anyway. Have a look here Jim Williams on eevblog https://tinyurl.com/nhyvtc3 CFO ___ 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] fast edge, rise time.
Am 26.12.2013 17:07, schrieb ct1dmk: p.s. ( I switch a capacitor to GND with a transistor (fet or bipolar). that capacitor has a charging resistor to 48V, transformer has a 9:1 voltage ratio. Pulse average power is quite low a few watt only. At the primary side some 20A of peak current for less than 100ns... and very low duty cycle. ) We once built an ultrasonic pipeline pig with 1024 transmit/receive channels, so everything had to be quite compact. The transmitting parts of the transducers were hit with 350V pulses with a few ns risetime and 50 Ohm source impedance and they rang on their favourite frequency. No transformer at all. We used avalanche transistors to produce the pulses, a small smd bipolar made by Zetex (afaik that's now bought up by Diodes, inc). Old 2N3904 are said to avalanche also quite good. The drawback is the repetition rate. Doing it as a 'normal' amplifier w/o transformer will require a cascode stage but should work also. But then I think you know that already since I've seen your presentation of the TWT switcher PS on the EME meeting in Paris 15?? years ago. :-) 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] fast edge, rise time.
On Thu, 26 Dec 2013 19:38:08 + (UTC) cfo xne...@luna.dyndns.dk wrote: Have a look here Jim Williams on eevblog https://tinyurl.com/nhyvtc3 I advice to be cautious with EEVblog. Dave Jones has a lot of half knowledge and presents that like he knew exactly what he is talking about. His videos usally contain a lot of errors. The videos are usally good enough to get you started with something you dont know anything about, but please double check every information you get from there. Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] fast edge, rise time.
Many thanks to all for the nice tips. I may narrow down by saying a few more specs as suggested. The pulse would see a somehow unknown load but for a start I was suggested to have my source with 50ohm impedance so worst case would be a short circuit and therefore the pulse would be a current pulse and would have some 10Amp. Pulse length about 100ns so only some 0.5mJ energy that would die inside the pulse source( this would be the worst case). The 100us repetition rate make a a very small duty cycle of 1/1000 so average power maximum 5W. Since the amplitude and timing parameters are to be controlled (pulse timing come from an FPGA) I really need a solution using that trivial switching element fet or bipolar (and can't really do a more exotic scheme if I cant electronically control the parameters) also I must use a transformer because these short pulse are to be superimposed to another voltage and a transformer becomes very handy to do that. I interrupt the wire and insert the secondary there to add the pulses. The challenge I'm facing is on the device either RF FET or Biplolar tr etc. and surrounding circuits, transformer, etc. this to achieve the 4ns (or 5ns). (the transformer I have in mind is something very similar to those transformers on the final stages of HF/VHF ham radio amps, coax cables and ferrite cores) any suggestion regarding devices etc ?... Thanks for all comments. Luis Cupido. ___ 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] fast edge, rise time.
Are only the amplitude and rep rate variable, or do you vary the width too? -John = Many thanks to all for the nice tips. I may narrow down by saying a few more specs as suggested. The pulse would see a somehow unknown load but for a start I was suggested to have my source with 50ohm impedance so worst case would be a short circuit and therefore the pulse would be a current pulse and would have some 10Amp. Pulse length about 100ns so only some 0.5mJ energy that would die inside the pulse source( this would be the worst case). The 100us repetition rate make a a very small duty cycle of 1/1000 so average power maximum 5W. Since the amplitude and timing parameters are to be controlled (pulse timing come from an FPGA) I really need a solution using that trivial switching element fet or bipolar (and can't really do a more exotic scheme if I cant electronically control the parameters) also I must use a transformer because these short pulse are to be superimposed to another voltage and a transformer becomes very handy to do that. I interrupt the wire and insert the secondary there to add the pulses. The challenge I'm facing is on the device either RF FET or Biplolar tr etc. and surrounding circuits, transformer, etc. this to achieve the 4ns (or 5ns). (the transformer I have in mind is something very similar to those transformers on the final stages of HF/VHF ham radio amps, coax cables and ferrite cores) any suggestion regarding devices etc ?... Thanks for all comments. Luis Cupido. ___ 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] fast edge, rise time.
Hi Unless you want run for 1 second, that rules out a Krytron. Length of operation also impacts some of the other implementations. Bob On Dec 26, 2013, at 9:16 PM, ct1dmk ct1...@gmail.com wrote: Many thanks to all for the nice tips. I may narrow down by saying a few more specs as suggested. The pulse would see a somehow unknown load but for a start I was suggested to have my source with 50ohm impedance so worst case would be a short circuit and therefore the pulse would be a current pulse and would have some 10Amp. Pulse length about 100ns so only some 0.5mJ energy that would die inside the pulse source( this would be the worst case). The 100us repetition rate make a a very small duty cycle of 1/1000 so average power maximum 5W. Since the amplitude and timing parameters are to be controlled (pulse timing come from an FPGA) I really need a solution using that trivial switching element fet or bipolar (and can't really do a more exotic scheme if I cant electronically control the parameters) also I must use a transformer because these short pulse are to be superimposed to another voltage and a transformer becomes very handy to do that. I interrupt the wire and insert the secondary there to add the pulses. The challenge I'm facing is on the device either RF FET or Biplolar tr etc. and surrounding circuits, transformer, etc. this to achieve the 4ns (or 5ns). (the transformer I have in mind is something very similar to those transformers on the final stages of HF/VHF ham radio amps, coax cables and ferrite cores) any suggestion regarding devices etc ?... Thanks for all comments. Luis Cupido. ___ 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] fast edge, rise time.
There are some good alternatives to krytrons. Just don't expect to be able to afford or export them. ;) On Dec 26, 2013, at 21:26, Bob Camp li...@rtty.us wrote: Hi Unless you want run for 1 second, that rules out a Krytron. Length of operation also impacts some of the other implementations. Bob On Dec 26, 2013, at 9:16 PM, ct1dmk ct1...@gmail.com wrote: Many thanks to all for the nice tips. I may narrow down by saying a few more specs as suggested. The pulse would see a somehow unknown load but for a start I was suggested to have my source with 50ohm impedance so worst case would be a short circuit and therefore the pulse would be a current pulse and would have some 10Amp. Pulse length about 100ns so only some 0.5mJ energy that would die inside the pulse source( this would be the worst case). The 100us repetition rate make a a very small duty cycle of 1/1000 so average power maximum 5W. Since the amplitude and timing parameters are to be controlled (pulse timing come from an FPGA) I really need a solution using that trivial switching element fet or bipolar (and can't really do a more exotic scheme if I cant electronically control the parameters) also I must use a transformer because these short pulse are to be superimposed to another voltage and a transformer becomes very handy to do that. I interrupt the wire and insert the secondary there to add the pulses. The challenge I'm facing is on the device either RF FET or Biplolar tr etc. and surrounding circuits, transformer, etc. this to achieve the 4ns (or 5ns). (the transformer I have in mind is something very similar to those transformers on the final stages of HF/VHF ham radio amps, coax cables and ferrite cores) any suggestion regarding devices etc ?... Thanks for all comments. Luis Cupido. ___ 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.
