Re: HP8640B RF Fails Several Seconds After Power Up
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 !
?
?
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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
?
?
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
?
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
?
?
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?
?
?
?
?
|
Re: 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:
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
?
?
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
?
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
?
?
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?
?
?
?
|
Re: HP 6209B repair - Some success
I am still working on repairing my HP6209B power supply. I have replaced all the electrolytic caps which I was planning on doing anyway once I got the supply running just due to age. And I replaced CR35 the Pre regulator SCR with a TYN606 SCR which was as close as I could get to the 2N4102 scr that was originally specified. Which interestingly enough, the SCR that was in there WAS an HP change. The 08-0302 I found out is a HP 1884-0302 part number, which I cannot find a cross reference for. And I replaced CR36 which is listed as HP 1901-0033 which I think cross referenced to a 1N645 diode. Which to me looks like a pretty basic diode. This part was giving me an odd reading. Using my Fluke 189 DVM I would expect to see a .65 forward voltage drop and was getting something like 1.83 and nothing reversed. I replaced it with a 1N4007. And lastly I changed C26 in the turn on control circuit from 20UF to 47uf to give a longer time for the supply to power on and settle¡
With all of that, the supply is behaving far more stably! I can flip the power switch on and within 2 seconds it comes up to whatever voltage it is set at. Full up on the voltage control now stops at 320V where it should. I can adjust it all the way down to zero with only 3.3ma across the voltage pot. And it appears all is working well! The ONLY issue I have found and it may not really be an issue¡I am still using a single turn 100K pot for the Voltage control just until I am 100% certain I am not going to burn up another near $40 part! I noticed that when you adjust the pot quickly at voltages of 100V or less, the current through the pot jumps up and can peak at 5-10ma through the pot momentarily until the supply catches up and settles in, at which point the current is back to 3.3ma through the pot. With the slow changes of the 10 turn pot. It may not be an issue. HOWEVER¡that makes me wonder what would happen if there was a load on the supply and then suddenly the load was removed, would we see that same spike in current through the pot??? Not sure.
Tomorrow I will run the supply through the full calibration and test out procedures. Maybe with the new parts in there now we are off just enough to cause that issue.
So progress. Getting there.
Dave
|
Re: HP8640B RF Fails Several Seconds After Power Up
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
?
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
?
?
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?
?
?
?
|
Re: HP8640B RF Fails Several Seconds After Power Up
I agree 100%? Ing. Patricio A. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+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
Aeron¨¢utico de
Reparaci¨®n
1B-349
Organizaci¨®n
de
Mantenimiento
Aeron¨¢utico de
la Defensa
OMAD-001
Gral.
Mart¨ªn
Rodr¨ªguez 2159
San
Miguel (1663)
Buenos
Aires
T:?+5411-4455-2557
F:?+5411-4032-0072
?
For best phase-noise I would recommend
finding a SiGe Device like the BFP740 or similar ,
Infineon and NXP both make great devices
?
?
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?
?
|
Re: 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:
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
?
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
?
?
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?
?
?
|
Re: HP8640B RF Fails Several Seconds After Power Up
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
?
?
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?
?
?
|
Re: HP8640B RF Fails Several Seconds After Power Up
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
Aeron¨¢utico de
Reparaci¨®n
1B-349
Organizaci¨®n
de
Mantenimiento
Aeron¨¢utico de
la Defensa
OMAD-001
Gral.
Mart¨ªn
Rodr¨ªguez 2159
San
Miguel (1663)
Buenos
Aires
T:?+5411-4455-2557
F:?+5411-4032-0072
?
For best phase-noise I would recommend
finding a SiGe Device like the BFP740 or similar ,
Infineon and NXP both make great devices
?
?
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?
?
|
Re: 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:
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
?
?
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?
?
|
Re: HP8640B RF Fails Several Seconds After Power Up
Phase noise is a characteristic of high Q resonant cavity . Or course the transistors incides but more the resonant circuit .? Ing. Patricio A. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+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
?
?
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?
?
|
Re: HP8640B RF Fails Several Seconds After Power Up
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?
?
|
Re: HP8640B RF Fails Several Seconds After Power Up
I¡¯ve an 8640A is a great equipment. No replacement for certain applications due extremely low phase noise? Ing. Patricio A. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+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. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+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
Aeron¨¢utico de
Reparaci¨®n
1B-349
Organizaci¨®n
de
Mantenimiento
Aeron¨¢utico de
la Defensa
OMAD-001
Gral.
Mart¨ªn
Rodr¨ªguez 2159
San
Miguel (1663)
Buenos
Aires
T:?+5411-4455-2557
F:?+5411-4032-0072
?
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?
|
Re: HP8640B RF Fails Several Seconds After Power Up
Let me check . I¡¯m back to my shop on Friday. I¡¯ll be back? Ing. Patricio A. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+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
Aeron¨¢utico de
Reparaci¨®n
1B-349
Organizaci¨®n
de
Mantenimiento
Aeron¨¢utico de
la Defensa
OMAD-001
Gral.
Mart¨ªn
Rodr¨ªguez 2159
San
Miguel (1663)
Buenos
Aires
T:?+5411-4455-2557
F:?+5411-4032-0072
?
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?
|
Re: 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:
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?
|
Re: HP8640B RF Fails Several Seconds After Power Up
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
Aeron¨¢utico de
Reparaci¨®n
1B-349
Organizaci¨®n
de
Mantenimiento
Aeron¨¢utico de
la Defensa
OMAD-001
Gral.
Mart¨ªn
Rodr¨ªguez 2159
San
Miguel (1663)
Buenos
Aires
T:?+5411-4455-2557
F:?+5411-4032-0072
?
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?
|
Re: HP8640B RF Fails Several Seconds After Power Up
What is the package of original transistor ?? I think I¡¯ve a replacement.? Ing. Patricio A. GrecoTaller Aeron¨¢utico de Reparaci¨®n 1B-349Organizaci¨®n de Mantenimiento Aeron¨¢utico de la Defensa OMAD-001Gral. Mart¨ªn Rodr¨ªguez 2159San Miguel (1663)Buenos AiresT:?+5411-4455-2557F:?+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?
|
Re: HP8640B RF Fails Several Seconds After Power Up
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?
|
Re: HP 8663A auxiliary fuse opening
Just to note that Aux transformer and the +-15V supplies are entirely used inside the power supply card cage and oven. It does not supply power to any of the rest of the machine.
Dan in Chandler, AZ
|
Re: HP-8753E Test Fixture Offset Value
Seems interesting result - I would have expected the open to be more problematic because of fringing. Any idea as to what was actually going on?
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
toggle quoted message
Show quoted text
I never quantified it , normally for on Wafer calibration to the probe tip the short standard is nothing but a shorting bar on the substrate but for offset shorts it becomes a different story .
When I did characterization for GaN devices both LP and S-parameter the recticles had short and open reflect standards and there was a consistent and repeatable difference in results and we were adviced upon completed data review not to use the short !
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Bruce via groups.io
Sent: Wednesday, April 13, 2022 3:18 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP-8753E Test Fixture Offset Value
Lothar -
Interesting. For the case of vias are not being required, how much difference in accuracy between short and open (assuming optimal design of the test board) do you observe as a function of frequency ??
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
Generally whether to use open or short depends on the
fixture/application , for mechanical fixtures like ICM a short is
often easier to realize and as David pointed out better but for test
boards or on wafer measurements I found the use of a open to yield
more accurate results especially at higher frequencies , the problem
here is that in those apps a short requires the use of vias which adds
inductance
From: [email protected]
<[email protected]> On Behalf Of Rich Miller via
groups.io
Sent: Wednesday, April 13, 2022 8:43 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP-8753E Test Fixture
Offset Value
Thanks for this information, I think it¡¯s pointing me in the right
direction. I will also review the application note Lothar sent over.
There is a whole section on TRL, but I had not correlated TRL to this
application in my mind.
The application is low UHF, and I would be ok if my total accuracy
displayed was +/- .5dB. I simply was trying to avoid having to look at
the instrument and then account for the fixture loss. The fixture is
about flat and consistent in the frequency ranges I am currently
working with. There is almost no noticeable deviation across the DUT¡¯s
B/W (it¡¯s in the .1 dB range).
While I am using the real numbers in Excel, I could easily get away
with simply having the analyzer calculate out the 40dB loss of my
fixture for this application. While I understand this may be a
acceptable practice for this DUT, it will not be for others I work
with, which would be around L-Band, because of the high degree of
variation in the frequency response of a fixture at those frequencies.
Rich
On Apr 13, 2022, at 6:48 AM, Dr. David Kirkby, Kirkby Microwave Ltd
<drkirkby@...<mailto:drkirkby@...>
wrote:
?
On Wed, 13 Apr 2022 at 03:58, Lothar baier
<Lothar@...<mailto:Lothar@...>> wrote:
disadvantage of TRL is that below 2GHz your delay lines become too
long so you have to go to SOLT which requires a Short , open , thru
and load the disadvantage of fixture boards is that you need to solder
the device down while fixtures usually clamp
Also, you really want a VNA with 2 reference receivers (4 receivers in
total), which the 8753E does not have. But it does have TRL*, which is
a sort of poor-man's TRL where the reference is sharted between the
two ports. But you need 6-10 dB attenuators on the ports so the
impedance remains relatively constant, despite internal switching in
the VNA. This reduces dynamic range.
I don't know the particular fixture, but it may be possible to put a
short where the DUT goes, then add a port extension until the phase is
180 degrees. If that's reasonably flat, and the magnitude of the
attenuation not excessive, then you can fairly easily do it on an
8753E. A short is better than an open, as a short has a phase of very
close to 180 degrees, whereas an open is not so close to 180 degrees
due to the fringing capacitance.
Dave
|
Re: HP-8753E Test Fixture Offset Value
I never quantified it , normally for on Wafer calibration to the probe tip the short standard is nothing but a shorting bar on the substrate but for offset shorts it becomes a different story .
When I did characterization for GaN devices both LP and S-parameter the recticles had short and open reflect standards and there was a consistent and repeatable difference in results and we were adviced upon completed data review not to use the short !
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Bruce via groups.io Sent: Wednesday, April 13, 2022 3:18 PM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP-8753E Test Fixture Offset Value Lothar - Interesting. For the case of vias are not being required, how much difference in accuracy between short and open (assuming optimal design of the test board) do you observe as a function of frequency ?? Cheers! Bruce Quoting Lothar baier <Lothar@...>: Generally whether to use open or short depends on the
fixture/application , for mechanical fixtures like ICM a short is
often easier to realize and as David pointed out better but for test
boards or on wafer measurements I found the use of a open to yield
more accurate results especially at higher frequencies , the problem
here is that in those apps a short requires the use of vias which adds
inductance
From: [email protected]
<[email protected]> On Behalf Of Rich Miller via
groups.io
Sent: Wednesday, April 13, 2022 8:43 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP-8753E Test Fixture
Offset Value
Thanks for this information, I think it¡¯s pointing me in the right
direction. I will also review the application note Lothar sent over.
There is a whole section on TRL, but I had not correlated TRL to this
application in my mind.
The application is low UHF, and I would be ok if my total accuracy
displayed was +/- .5dB. I simply was trying to avoid having to look at
the instrument and then account for the fixture loss. The fixture is
about flat and consistent in the frequency ranges I am currently
working with. There is almost no noticeable deviation across the DUT¡¯s
B/W (it¡¯s in the .1 dB range).
While I am using the real numbers in Excel, I could easily get away
with simply having the analyzer calculate out the 40dB loss of my
fixture for this application. While I understand this may be a
acceptable practice for this DUT, it will not be for others I work
with, which would be around L-Band, because of the high degree of
variation in the frequency response of a fixture at those frequencies.
Rich
On Apr 13, 2022, at 6:48 AM, Dr. David Kirkby, Kirkby Microwave Ltd
<drkirkby@...<mailto:drkirkby@...>
wrote:
?
On Wed, 13 Apr 2022 at 03:58, Lothar baier
<Lothar@...<mailto:Lothar@...>> wrote:
disadvantage of TRL is that below 2GHz your delay lines become too
long so you have to go to SOLT which requires a Short , open , thru
and load the disadvantage of fixture boards is that you need to solder
the device down while fixtures usually clamp
Also, you really want a VNA with 2 reference receivers (4 receivers in
total), which the 8753E does not have. But it does have TRL*, which is
a sort of poor-man's TRL where the reference is sharted between the
two ports. But you need 6-10 dB attenuators on the ports so the
impedance remains relatively constant, despite internal switching in
the VNA. This reduces dynamic range.
I don't know the particular fixture, but it may be possible to put a
short where the DUT goes, then add a port extension until the phase is
180 degrees. If that's reasonably flat, and the magnitude of the
attenuation not excessive, then you can fairly easily do it on an
8753E. A short is better than an open, as a short has a phase of very
close to 180 degrees, whereas an open is not so close to 180 degrees
due to the fringing capacitance.
Dave
|
Patricio A. Greco
Flannel Tuba