Also of some vague relevance.......

On Wed, Apr 13, 2022 at 2:52 AM Arie de Muijnck <mygroups@...> wrote:

On 2022-04-13 02:16, Flannel Tuba wrote:

Greetings,?

I am finally getting back to this project and have narrowed the problem to a failing transistor in the A3 Main Oscillator. Fortunately this is a relatively easy part to get to once you know its secret hidey-hole under the large hex cap on the top of the oscillator body. (See this OCRed article from the Sept/Oct 2005 QEX magazine:??and search for HP8640 There's a marvelous description of how to disassemble the A3 unit to get to the electronics, and how to spot one of the most common problems -- loss of either +20v or - 20v at the Q1 transistor socket).

Anyway, having found the main oscillator transistor A3 Q1, and demonstrating that it was failing using a Huntron curve tracer (and some freeze spray!), I am now looking for a suitable replacement. The HP part number on the parts list is 5086-7082, whereas on the schematic itself, it's listed as 5086-4282.

So can anyone direct me to an equivalent to either a 5086-7082 or 5086-4282 NPN transistor, or a spec sheet that I can use to try and match the original?

Thanks,
Scott

Thanks for the link to that great archive! A direct link to the article as PDF is here, at page 35:

??

Arie

#125173

Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition.

Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.?

Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082.

I'll let you know what I find.

-Scott?

#125174

David Holland All Messages By This Member #125160 Also of some vague relevance....... toggle quoted message Show quoted text On Wed, Apr 13, 2022 at 2:52 AM Arie de Muijnck <mygroups@...> wrote: On 2022-04-13 02:16, Flannel Tuba wrote: Greetings,? I am finally getting back to this project and have narrowed the problem to a failing transistor in the A3 Main Oscillator. Fortunately this is a relatively easy part to get to once you know its secret hidey-hole under the large hex cap on the top of the oscillator body. (See this OCRed article from the Sept/Oct 2005 QEX magazine:??and search for HP8640 There's a marvelous description of how to disassemble the A3 unit to get to the electronics, and how to spot one of the most common problems -- loss of either +20v or - 20v at the Q1 transistor socket). Anyway, having found the main oscillator transistor A3 Q1, and demonstrating that it was failing using a Huntron curve tracer (and some freeze spray!), I am now looking for a suitable replacement. The HP part number on the parts list is 5086-7082, whereas on the schematic itself, it's listed as 5086-4282. So can anyone direct me to an equivalent to either a 5086-7082 or 5086-4282 NPN transistor, or a spec sheet that I can use to try and match the original? Thanks, Scott Thanks for the link to that great archive! A direct link to the article as PDF is here, at page 35: ?? Arie
Flannel Tuba All Messages By This Member #125173 Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott?
Patricio A. Greco All Messages By This Member #125174 开云体育 What is the package of original transistor ?? I think I’ve a replacement.? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 toggle quoted message Show quoted text On 13 Apr 2022, at 20:44, Flannel Tuba <flanneltuba@...> wrote: ? Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott?
Tom Lee All Messages By This Member #125175 开云体育 It's a TO-72 (similar to a TO-18), but the can is connected to the base, not the collector. That's what makes finding a replacement challenging. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:57, Patricio A. Greco via groups.io wrote: toggle quoted message Show quoted text What is the package of original transistor ?? I think I’ve a replacement.? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 On 13 Apr 2022, at 20:44, Flannel Tuba <flanneltuba@...> wrote: ? Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott?
Tom Lee All Messages By This Member #125176 开云体育 Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: toggle quoted message Show quoted text Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott?
Patricio A. Greco All Messages By This Member #125177 开云体育 Let me check . I’m back to my shop on Friday. I’ll be back? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 toggle quoted message Show quoted text On 13 Apr 2022, at 21:06, Tom Lee <tomlee@...> wrote: ? It's a TO-72 (similar to a TO-18), but the can is connected to the base, not the collector. That's what makes finding a replacement challenging. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:57, Patricio A. Greco via groups.io wrote: What is the package of original transistor ?? I think I’ve a replacement.? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 On 13 Apr 2022, at 20:44, Flannel Tuba <flanneltuba@...> wrote: ? Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott?
Patricio A. Greco All Messages By This Member #125178 开云体育 I’ve an 8640A is a great equipment. No replacement for certain applications due extremely low phase noise? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 toggle quoted message Show quoted text On 13 Apr 2022, at 21:32, Patricio A. Greco via groups.io <patricio_greco@...> wrote: ?Let me check . I’m back to my shop on Friday. I’ll be back? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 On 13 Apr 2022, at 21:06, Tom Lee <tomlee@...> wrote: ? It's a TO-72 (similar to a TO-18), but the can is connected to the base, not the collector. That's what makes finding a replacement challenging. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:57, Patricio A. Greco via groups.io wrote: What is the package of original transistor ?? I think I’ve a replacement.? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 On 13 Apr 2022, at 20:44, Flannel Tuba <flanneltuba@...> wrote: ? Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott?
Lothar baier #125179 开云体育 For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ?
Patricio A. Greco All Messages By This Member #125180 开云体育 Phase noise is a characteristic of high Q resonant cavity . Or course the transistors incides but more the resonant circuit .? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 toggle quoted message Show quoted text On 13 Apr 2022, at 22:16, Lothar baier <Lothar@...> wrote: ? For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ?
Tom Lee All Messages By This Member #125181 开云体育 A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: toggle quoted message Show quoted text For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ?
Tom Lee All Messages By This Member #125182 开云体育 What you say is largely true for the 1/f^2 part of the spectrum, but for close-in (1/f^3) phase noise, the device itself makes a large difference. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:32, Patricio A. Greco via groups.io wrote: toggle quoted message Show quoted text Phase noise is a characteristic of high Q resonant cavity . Or course the transistors incides but more the resonant circuit .? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 On 13 Apr 2022, at 22:16, Lothar baier <Lothar@...> wrote: ? For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ?
Lothar baier #125183 开云体育 Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ?
Tom Lee All Messages By This Member #125184 开云体育 I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: toggle quoted message Show quoted text Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ?
Patricio A. Greco All Messages By This Member #125185 开云体育 I agree 100%? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 toggle quoted message Show quoted text On 13 Apr 2022, at 22:34, Tom Lee <tomlee@...> wrote: ? What you say is largely true for the 1/f^2 part of the spectrum, but for close-in (1/f^3) phase noise, the device itself makes a large difference. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:32, Patricio A. Greco via groups.io wrote: Phase noise is a characteristic of high Q resonant cavity . Or course the transistors incides but more the resonant circuit .? Ing. Patricio A. Greco Taller Aeronáutico de Reparación 1B-349 Organización de Mantenimiento Aeronáutico de la Defensa OMAD-001 Gral. Martín Rodríguez 2159 San Miguel (1663) Buenos Aires T:?+5411-4455-2557 F:?+5411-4032-0072 On 13 Apr 2022, at 22:16, Lothar baier <Lothar@...> wrote: ? For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ?
Lothar baier #125186 开云体育 Apologies I didn’t see this one as for some reason the message didn’t show in my email box but after going through the thread on the group I found it ! Most SiGe devices I know of are designed for lower voltages probably because nowadays with everything being battery operated higher voltage devices are no longer a thing but that’s just a theory ! Unfortunately I am no longer at a job dealing with MMIC design but one could conceivably find a silicon or SiGe Process that accommodates those specs and jump on a pizza mask to get some dies and then bond them in a TO-18 can ……….? , with a ton of 8640 out there it might be worth considering ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:43 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ? ?
Tom Lee All Messages By This Member #125188 开云体育 Yes, it would be fun to crank out a run of these transistors. One wafer would yield enough to keep our 8640s working pretty much for as long as anyone would want. I've always fantasized about a desktop fab that could do something like that. Surprising how difficult it is to replicate 1970s technology with 21st-century tools! -- Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 19:47, Lothar baier wrote: toggle quoted message Show quoted text Apologies I didn’t see this one as for some reason the message didn’t show in my email box but after going through the thread on the group I found it ! Most SiGe devices I know of are designed for lower voltages probably because nowadays with everything being battery operated higher voltage devices are no longer a thing but that’s just a theory ! Unfortunately I am no longer at a job dealing with MMIC design but one could conceivably find a silicon or SiGe Process that accommodates those specs and jump on a pizza mask to get some dies and then bond them in a TO-18 can ……….? , with a ton of 8640 out there it might be worth considering ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:43 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ? ?
Lothar baier #125189 开云体育 I know that pretty much every foundry offers shared wafer runs , back when I worked at UT all of the student and research ?projects were combined and then send to the foundry to be put on a pizza mask , they did the processing and dicing and you got a waffle pack with the devices , silicon is cheap and widespread and there are quite a few foundries in Taiwan and korea that are cheap ! ? ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 10:17 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Yes, it would be fun to crank out a run of these transistors. One wafer would yield enough to keep our 8640s working pretty much for as long as anyone would want. I've always fantasized about a desktop fab that could do something like that. Surprising how difficult it is to replicate 1970s technology with 21st-century tools! -- Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 19:47, Lothar baier wrote: Apologies I didn’t see this one as for some reason the message didn’t show in my email box but after going through the thread on the group I found it ! Most SiGe devices I know of are designed for lower voltages probably because nowadays with everything being battery operated higher voltage devices are no longer a thing but that’s just a theory ! Unfortunately I am no longer at a job dealing with MMIC design but one could conceivably find a silicon or SiGe Process that accommodates those specs and jump on a pizza mask to get some dies and then bond them in a TO-18 can ……….? , with a ton of 8640 out there it might be worth considering ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:43 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ? ? ?
Lothar baier #125190 开云体育 I am somewhat curious about the part numbering , HP-21 doesn’t fit into any of the numbering conventions for a part or product so I was wondering if this potentially was a part that was especially designed for the 8640 series . ? ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 10:17 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Yes, it would be fun to crank out a run of these transistors. One wafer would yield enough to keep our 8640s working pretty much for as long as anyone would want. I've always fantasized about a desktop fab that could do something like that. Surprising how difficult it is to replicate 1970s technology with 21st-century tools! -- Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 19:47, Lothar baier wrote: Apologies I didn’t see this one as for some reason the message didn’t show in my email box but after going through the thread on the group I found it ! Most SiGe devices I know of are designed for lower voltages probably because nowadays with everything being battery operated higher voltage devices are no longer a thing but that’s just a theory ! Unfortunately I am no longer at a job dealing with MMIC design but one could conceivably find a silicon or SiGe Process that accommodates those specs and jump on a pizza mask to get some dies and then bond them in a TO-18 can ……….? , with a ton of 8640 out there it might be worth considering ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:43 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ? ? ?
Tom Lee All Messages By This Member #125192 开云体育 The HP-21 may very well have been specially made for the 8640. The only Google hits point to that sig gen. I was once told by an HP oldtimer that the 358xx series was derived from this part (or maybe it was the other way around), but he was not at all certain. The 35824E is in a TO-72 and has specs that look a lot like the ones I found in that one paper's footnote, but I do not know if the case is tied to the base. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 21:08, Lothar baier wrote: toggle quoted message Show quoted text I am somewhat curious about the part numbering , HP-21 doesn’t fit into any of the numbering conventions for a part or product so I was wondering if this potentially was a part that was especially designed for the 8640 series . ? ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 10:17 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Yes, it would be fun to crank out a run of these transistors. One wafer would yield enough to keep our 8640s working pretty much for as long as anyone would want. I've always fantasized about a desktop fab that could do something like that. Surprising how difficult it is to replicate 1970s technology with 21st-century tools! -- Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 19:47, Lothar baier wrote: Apologies I didn’t see this one as for some reason the message didn’t show in my email box but after going through the thread on the group I found it ! Most SiGe devices I know of are designed for lower voltages probably because nowadays with everything being battery operated higher voltage devices are no longer a thing but that’s just a theory ! Unfortunately I am no longer at a job dealing with MMIC design but one could conceivably find a silicon or SiGe Process that accommodates those specs and jump on a pizza mask to get some dies and then bond them in a TO-18 can ……….? , with a ton of 8640 out there it might be worth considering ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:43 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ? ? ?
Tom Lee All Messages By This Member #125193 开云体育 Oh, silly me: I forgot the very paper I've cited, which describes a YTO using that same transistor. So, at least two products used that transistor. -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 21:48, Tom Lee wrote: toggle quoted message Show quoted text The HP-21 may very well have been specially made for the 8640. The only Google hits point to that sig gen. I was once told by an HP oldtimer that the 358xx series was derived from this part (or maybe it was the other way around), but he was not at all certain. The 35824E is in a TO-72 and has specs that look a lot like the ones I found in that one paper's footnote, but I do not know if the case is tied to the base. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 21:08, Lothar baier wrote: I am somewhat curious about the part numbering , HP-21 doesn’t fit into any of the numbering conventions for a part or product so I was wondering if this potentially was a part that was especially designed for the 8640 series . ? ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 10:17 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Yes, it would be fun to crank out a run of these transistors. One wafer would yield enough to keep our 8640s working pretty much for as long as anyone would want. I've always fantasized about a desktop fab that could do something like that. Surprising how difficult it is to replicate 1970s technology with 21st-century tools! -- Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 19:47, Lothar baier wrote: Apologies I didn’t see this one as for some reason the message didn’t show in my email box but after going through the thread on the group I found it ! Most SiGe devices I know of are designed for lower voltages probably because nowadays with everything being battery operated higher voltage devices are no longer a thing but that’s just a theory ! Unfortunately I am no longer at a job dealing with MMIC design but one could conceivably find a silicon or SiGe Process that accommodates those specs and jump on a pizza mask to get some dies and then bond them in a TO-18 can ……….? , with a ton of 8640 out there it might be worth considering ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:43 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? I gave the specs earlier in the thread. Knowing those in advance of recommending a device improves SNR. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:36, Lothar baier wrote: Since I don’t know the specs of the original device I cant really judge which device would be feasible , I chose the BFP740 because I used it in the past in low phase-noise oscillator circuits , there is a slew of other devices out there with lower FT From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 8:33 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? A BFP740 is, in a sense, much too fast. By that I mean that other parameters have been traded off in exchange for high ft. BVCBO is too low, and so is the power dissipation spec, for example. --Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 18:16, Lothar baier wrote: For best phase-noise I would recommend finding a SiGe Device like the BFP740 or similar , Infineon and NXP both make great devices ? From: [email protected] <[email protected]> On Behalf Of Tom Lee via groups.io Sent: Wednesday, April 13, 2022 7:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up ? Re: Ft overhead: Keep in mind that you need more gain than the minimum that sustains oscillation in the absence of a load -- you need enough to support the power delivered to a load. On top of that, you don't want the frequency of oscillation to be affected too much by the transistor's own phase shift -- you want the resonator to control it. All those considerations argue for a healthy ft margin. I'm sure you could sub a somewhat slower transistor and still get output, but you will sacrifice some of the famous (and hard-fought) stability for which the HP8640B is prized. -- Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/13/2022 16:44, Flannel Tuba wrote: Thank you, Arie for finding a link to the actual scanned? article! Having the pictures along with he text is quite a nice addition. Meanwhile, I have ordered a smattering of VHF and UHF transistors from Mouser with marginally similar ratings to those Tom provided. I do wonder about the fT of 5GHz though. The oscillator's range is from 230-550MHz, so I wonder why the extreme frequency overhead margin. I went ahead and ordered a dozen or so potential replacements having at least the Vcbo of 30v, Vceo of 20v, Vebo of 4v and fT of over 600MHz with several in the 1-5GHz range. A couple are TO92 packages, which I envision just folding the base lead across the top to make contact with the grounding hex cap nut/cover, but most are SOT-23, which I'll have to come up with an adapter of some sort for. Any ideas on this are more than welcome.? Well, if I'm lucky I'll have some time in the next few weekends to experiment with possible replacements for the rare and venerable HP 5086-7082. I'll let you know what I find. -Scott? ? ? ? ?

HP8640B RF Fails Several Seconds After Power Up