Browsing for older threads from the forum, I found?this:?. Very good stuff.? Radu.?
On Mon, Mar 7, 2022 at 10:32 AM Radu Bogdan Dicher via <vondicher= [email protected]> wrote: Bruce, I am still perusing the service manual, and am not yet sure how/where disconnecting it would be possible, but part of the issue here may be the unit it on just one or two PCBs. The adjustments for the LCD are all over the main board - in my unit (2948A+ serial number), the contrast adjustment?(R32) is way deep inside the unit, and not near the LCD, where I'd expect it.
Point being they seem to have kind of intertwined the LCD controls and power?supplying throughout the main board. The service manual seems kind of "end of an era" transition type, in between the exceptional service manuals from early days and the non-disclosure of later times. I, for one, am still looking for schematics for my HP54522A scope.?
If anyone has found disabling the 80V supply is the route, it'd be very appreciated sharing insight on the process.? Radu.?
On Mon, Mar 7, 2022 at 9:33 AM Bruce < bruce@...> wrote: Would disabling the 80v source be a big deal ??
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
> Doug and all,
> I just acquired one such unit (HP8904A), and indeed, it is?
> exceptionally accurate. Its 10MHz internal reference measures at?
> 4.1ppm off on my oven conditioned HP5328A, and the DC levels are?
> almost as accurate as I can measure them with my Fluke 8840a (for?
> instance, the 10V DC level reads at 10.0003V). AC amplitude levels?
> read with my HP54522A are at 0.00000V off for the 0.1 and 1000Hz?
> signal. Wherever I am seeing deviations, they are usually an order?
> of magnitude less than the allowed tolerance.
>
> Anyway, VERY impressed. This is a unit which, as far as I could put?
> it together, was in a maintained lab until some part of 2020, but?
> since has been on eBay at least twice. Funny thing is it's been last?
> looked at by a metrology lab in my literal neighborhood, then spent?
> these 1-2 years somewhere in AZ, then came back to the neighborhood?
> in CA to join my herd.
>
> Now, on to the issue at hand - I'm very interested in replacing the?
> LCD with a hopefully far more legible unit. Can anyone indicate some?
> clear directions, if available anywhere, and maybe LCD units to use?
> for this? I've seen Doug's recommendation, but I'm a bit weary the?
> shield doesn't seem to fit behind it. The other concern is with the?
> 80V source for the old unit that seems to need a load of sorts to be?
> happy.
> Radu.
>
>
>
|
When you buy your BeagleBone, be sure to get the BeagleBone Black. The BeagleBone Green from Seeed Studio isn¡¯t compatible with the 5370 emulator software.?
I should have another look at it, having learned a bit about these single board computers since I last looked at it.?
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Show quoted text
On Mar 7, 2022, at 12:20, Bob Stewart <bob@...> wrote:
? Hi Richard,
I'll announce when/if I decide to buy boards.? Be aware they will be purple, though!? :)
On Monday, March 7, 2022, 11:59:02 AM CST, Richard Hall <rhall2@...> wrote:
Bob,
I have a several HP 5370A that I am repairing.
If you have boards made I am interested in buying from 1 to 3 sets.
Richard Hall
WB4RSO
|
Bruce, I am still perusing the service manual, and am not yet sure how/where disconnecting it would be possible, but part of the issue here may be the unit it on just one or two PCBs. The adjustments for the LCD are all over the main board - in my unit (2948A+ serial number), the contrast adjustment?(R32) is way deep inside the unit, and not near the LCD, where I'd expect it.
Point being they seem to have kind of intertwined the LCD controls and power?supplying throughout the main board. The service manual seems kind of "end of an era" transition type, in between the exceptional service manuals from early days and the non-disclosure of later times. I, for one, am still looking for schematics for my HP54522A scope.?
If anyone has found disabling the 80V supply is the route, it'd be very appreciated sharing insight on the process.? Radu.?
On Mon, Mar 7, 2022 at 9:33 AM Bruce < bruce@...> wrote: Would disabling the 80v source be a big deal ??
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
> Doug and all,
> I just acquired one such unit (HP8904A), and indeed, it is?
> exceptionally accurate. Its 10MHz internal reference measures at?
> 4.1ppm off on my oven conditioned HP5328A, and the DC levels are?
> almost as accurate as I can measure them with my Fluke 8840a (for?
> instance, the 10V DC level reads at 10.0003V). AC amplitude levels?
> read with my HP54522A are at 0.00000V off for the 0.1 and 1000Hz?
> signal. Wherever I am seeing deviations, they are usually an order?
> of magnitude less than the allowed tolerance.
>
> Anyway, VERY impressed. This is a unit which, as far as I could put?
> it together, was in a maintained lab until some part of 2020, but?
> since has been on eBay at least twice. Funny thing is it's been last?
> looked at by a metrology lab in my literal neighborhood, then spent?
> these 1-2 years somewhere in AZ, then came back to the neighborhood?
> in CA to join my herd.
>
> Now, on to the issue at hand - I'm very interested in replacing the?
> LCD with a hopefully far more legible unit. Can anyone indicate some?
> clear directions, if available anywhere, and maybe LCD units to use?
> for this? I've seen Doug's recommendation, but I'm a bit weary the?
> shield doesn't seem to fit behind it. The other concern is with the?
> 80V source for the old unit that seems to need a load of sorts to be?
> happy.
> Radu.
>
>
>
|
Re: Low EMI lighting for labs and work areas
I totally agree with what Dave said about the video cables. I've seen all sorts, and dissected many over the years. I can usually tell just by looking at them, which ones are "good." The nice skinny, highly flexible ones tend to be the worst - the wiring is often just straight through, with not even twisted pairs for the RGBS signals. The good ones are much fatter and not so flexible, due to having actual individual coax lines for the video signals, and usually heavier outer shielding braid. They often have common-mode chokes molded right onto the cable, or tightly attached.
The skinny ones were just about adequate for VGA in the old days, but if used for more modern, higher resolution monitors, the video performance limits are obvious, and it's safe to say the EMC is much worse too.
Ed
|
Re: HP-8753E S11 Intermittent Results - Switch or Bridge?
Hi John:
This is very interesting information. I just ordered a known to be not functioning coupler assembly. I paid $15.00 for it. I do not need one, but I was very curious what is inside there and was not brave enough to open my known working couplers on the 8753E. I thought $15.00 a fair price for something I was just curious in learning about it¡¯s construction.
After all the testing, and reading yesterday, I had an idea that maybe I could take the broken coupler I picked up and turn it into a good Return Loss Bridge for use with my R3267 with TG. ?My current RLB only has usable directivity to 2.4GHz, so this could be a good upgrade, depending on what happened to it.?
Rich
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On Mar 7, 2022, at 12:58 PM, John Gord via groups.io <johngord@...> wrote:
?Lothar, Given the parts I still see on my shelf, I probably used 0402 1% surface mount resistors and conductive epoxy.? I think I may have used a couple in parallel for the low value resistor in an attempt to keep its inductance low.?? I never ran the official verification test (I don't have the verification kit), so I don't know if they would pass an official Keysight cal.? If they only check in the corrected state they would probably do fine. The uncorrected directivity spec at 3 GHz is 30dB, I am getting 24dB The uncorrected directivity spec at 6 GHz is 25dB, I am getting 14dB --John Gord On Sun, Mar 6, 2022 at 07:47 PM, Lothar baier wrote:
What resistors did you use and how did you mount them ?
I fixed a few bridges back when 8753 still sold for good money , I used beam lead resistors with 0.5% tolerance I glued them in with conductive epoxy and it worked fine , units passed cal
?
Lothar,
The couplers did sustain significant damage.? I had to replace the thin-film bridge resistors with surface mount resistors.? That no doubt added to the port match problems.
--John Gord
On Sun, Mar 6, 2022 at 08:02 AM, Lothar baier wrote:
the ESD diodes wouldn¡¯t go bad due to excess power , consider a few things here ?first of those diodes are high impedance not 50ohm they are in essence Zener diodes as a result they dont dissipate a lot of RF power , at he level required to damage the diodes the coupler would sustain significant damage as well !
What people however tend to forget is that ESD applied to the test port of the VNA can damage the diodes
?
Sent from for Windows
?
That is good information. That may be an alternative later. I am evaluating circuits where I need about 100dB of dynamic range. As such, I think its important to avoid this modification if at all possible. I managed to secure another switch, so I am hopeful it's not a dud.?
On Sunday, March 6, 2022, 12:39:12 AM EST, John Gord via groups.io <johngord@...> wrote:
I had some success in repairing the switches on a couple of 6GHz 8753D's that I bought in known "parts" condition.? In both cases, an ESD protection diode in the switch had gone short circuit, presumably from either an ESD event or excess power.? I crudely removed the shorted diodes, and the switches worked, but did not meet the original uncorrected port match specifications.? They work well enough for me when corrections are on.? I put a note on each to warn whomever gets the units when the kids eventually clean out the lab.
--John Gord
On Sat, Mar 5, 2022 at 08:30 PM, Lothar baier wrote:
As far as repairing a bad switch goes it would depend on your capabilities ?? those switches are not build using regular surface mount parts , the switch uses a gold plated block that has channels machined , inside those channels you have GaAs Switch dies that are wire bonded and attached using solder or conductive epoxy , its not trivial to remove and replace the dies you need wire bonders and die attach machine and finding the correct die is a whole different story , its not trivial at all
?
?
?
Sent from for Windows
?
?
I switched the physical coupler (did not modification around the swtich). I just moved Port 2 into Port 1 position. I have not installed the other coupler yet, so Port 1 (as seen from the front of the instrument) has my old Port 2 Coupler in it. Port 2 is Blank.
On Saturday, March 5, 2022, 10:38:59 PM EST, Lothar baier <lothar@...> wrote:
Just to double check if I understand this correctly , did you swap the couplers or did you flip the switch ports and switch ?
?
Sent from for Windows
?
?
Just got done removing Port 2 Coupler and placing it in the Port 1 Position. Problem follows, so I think this is kind of pointing towards the switch. I can say for sure the source is providing the correct power at 3.0 GHz. Whatever it's producing above 3 GHz I can say for sure, but it is stable. No erratic behavior when switching between the ports.?
On Saturday, March 5, 2022, 09:24:07 PM EST, Rich Miller via groups.io <av8torrich@...> wrote:
I was not able to take those measurements prior to pulling it apart.. What I can state is; S22 was rock solid with no such fluctuations, and passes all test without issue. Furthermore, S22 never fluctuates when moving to another measurement and back again. When I did power up the 8753E, the S11 response is normal, and remains normal until such time as I switch between another measurement. As a matter of fact, simply hitting S11 multiple times will straighten the response out, and also cause the response to go nutty. In short, if I cycle S11 multiple times I can either get a normal RL response, or something similar to what I showed in my original post.
What I am attempting now, is swapping Port 1 with Port 2, and see if the problem follows. I have it down in my lab in the basement where I do have a small ESD work area near where I solder. Good news is, we are at >70% humidity here in the mid Atlantic today so that should help eliminate some of the ESD Risk.
¸é¾±³¦³ó¡
?
From your picture, the problem is above 3 GHz. The Source oscillator does a major band switch at about 3 GHz, which suggests that might be where the problem is. The SS switch ¡®could¡¯ be erratic, but it just doesn¡¯t seem likely, especially since you are not seeing any power level changes.
?
When you power up and just let it run for a while without changing anything, does it stay good?
?
If you put a through between ports 1 and 2, and look at S21and S12, what happens?
?
Also, does S22 behave properly? From your original post, I believe it must be OK, but I¡¯m double checking that conclusion.
?
One caution about cables. They can build up static charge between the center and outer, which dumps into the ports when? connected. Usually only a concern with long cables, but¡
?
?
I just got done measuring the power out at Port 1. To my surprise, I cannot detect any significant power output fulgurations. I have tried 3GHz, 3.707GHz (worse offender in S11 Response), 4GHz and 5GHz.? They all look very stable, when switching back and forth. I am using a power meter which is not rated for accuracy at 3 - 6 GHz, but I can set the output to 0dBm look at the measurement, and switch back and forth and look for any relative change. It is not fluctuating whatsoever.?
I also checked 3GHz with my MDO, and that is a accurate power measurement. Now I am scratching my head again.
On Saturday, March 5, 2022, 07:16:43 PM EST, Lothar baier <lothar@...> wrote:
Try to find a cheap working 85047A ,? it uses the same inerts as the 8753D/E/ES including the solid state switch and you get 2 couplers as added bonus .
?
Take one word of caution though ,? when handling the switch use a ESD mat and wriststrap or at least put some esd caps or terminations on the SMA connectors ,? those suckers are really sensitive to ESD
?
Sent from for Windows
?
?
Yes, I am leaning this way (switch being the issue). I think it could also be that I was running a bunch of two port calibrations using a Agilent 85093 this morning (testing eCal out). I had some averaging on, 1601 Points, and 300KHz of IF B/W Set. Needless to say there was a lot of switching going on today. Let me check the power output now, and then flip it over and pray that one of the connectors on the switch is loose.
Looks like the parts hunt is likely on!
On Saturday, March 5, 2022, 06:55:27 PM EST, Lothar baier <lothar@...> wrote:
The reversing switches are notorious for failures especially if a unit is used in a environment that is not ESD protected .? what you can also do and you have to be cautious if you do this is to remove the switch , remove the hardline from the switch to coupler port 1 and connect the coupler directly to the source , if your trace is consistent then you definatly have a bad switch !
?
?
Sent from for Windows
?
?
It just started failing Port 1 Test. I was doing this just as this email came in. It is failing it consistently. I do not have a power meter, but I can take a look with my Spectrum Analyzer to see if there are power fluctuations at 3GHz. This problem seems to focus at frequencies higher than 3GHz.?
Once I have a look at the output power, I will open and have a look. This is a new problem, as I never saw this before.
On Saturday, March 5, 2022, 06:38:56 PM EST, Lothar baier <lothar@...> wrote:
If the S11response changes when you switch back and forth than this would point towards a repeatability issue with the solid state switch the fact that this changes with temperature would also point towards this direction , so here are a few things to try :
?
- Connect a short to port 1 ,? go to the service menu there is a op check for port 1 and 2 , run the op check several time first for port 1 then port 2 then go back to port 1 and so on , see if it passes consistently or if there is a failure
- If you have a power meter connect it to port 1 , change the analyzer to CW and a frequency close to the upper end (3 or 6GHz), set power to 0dBm and then switch back and forth between S11 and S22 measurement and see if the power changes
- Open the unit and check the hardline connetions , make sure the nuts are tight
?
Sent from for Windows
?
I have an issue with S11 (Port 1). It showed it's head now that I am running two port calibrations, thus I have not detected it just yet. My hunch is I have a problem with the switch, but not the Bridge. Here is what I am observing:
1. Upon boot up I get a good/normal S11 RL Response into a good 50 Ohm Load. This Condition will persist until I do one of the steps below.
2. If I switch to Port 2 (i.e. S22 Measurement), and then back to Port 1 the S11 Response has gone nutty (See Attached Picture).?
3. I have noticed, that if I depress the S11 MEAS multiple times, the S11 RL Response returns to normal.?
4. If you look at the enclosed picture, I have captured what I refer to as a normal S11 response, which I saved to memory (Smooth), and what it looks like after pressing S11 again (Wild variations in response).
I have noticed there is a stark difference between instrument, cold and warm on S11. I do not however see this behavior our of any of the Port 2 Measurements regardless of temperature. Is there anywhere else this could be coming from other than the Solid State Switch, or am I way off base in my thinking here??
|
Hi Richard,
I'll announce when/if I decide to buy boards.? Be aware they will be purple, though!? :)
On Monday, March 7, 2022, 11:59:02 AM CST, Richard Hall <rhall2@...> wrote:
Bob,
I have a several HP 5370A that I am repairing.
If you have boards made I am interested in buying from 1 to 3 sets.
Richard Hall
WB4RSO
|
Bob,
I have a several HP 5370A that I am repairing.
If you have boards made I am interested in buying from 1 to 3 sets.
Richard Hall
WB4RSO
|
Re: HP-8753E S11 Intermittent Results - Switch or Bridge?
Lothar,
Given the parts I still see on my shelf, I probably used 0402 1% surface mount resistors and conductive epoxy.? I think I may have used a couple in parallel for the low value resistor in an attempt to keep its inductance low.??
I never ran the official verification test (I don't have the verification kit), so I don't know if they would pass an official Keysight cal.? If they only check in the corrected state they would probably do fine.
The uncorrected directivity spec at 3 GHz is 30dB, I am getting 24dB
The uncorrected directivity spec at 6 GHz is 25dB, I am getting 14dB
--John Gord
toggle quoted message
Show quoted text
On Sun, Mar 6, 2022 at 07:47 PM, Lothar baier wrote:
What resistors did you use and how did you mount them ?
I fixed a few bridges back when 8753 still sold for good money , I used beam lead resistors with 0.5% tolerance I glued them in with conductive epoxy and it worked fine , units passed cal
?
Lothar,
The couplers did sustain significant damage.? I had to replace the thin-film bridge resistors with surface mount resistors.? That no doubt added to the port match problems.
--John Gord
On Sun, Mar 6, 2022 at 08:02 AM, Lothar baier wrote:
the ESD diodes wouldn¡¯t go bad due to excess power , consider a few things here ?first of those diodes are high impedance not 50ohm they are in essence Zener diodes as a result they dont dissipate a lot of RF power , at he level required to damage the diodes the coupler would sustain significant damage as well !
What people however tend to forget is that ESD applied to the test port of the VNA can damage the diodes
?
Sent from for Windows
?
That is good information. That may be an alternative later. I am evaluating circuits where I need about 100dB of dynamic range. As such, I think its important to avoid this modification if at all possible. I managed to secure another switch, so I am hopeful it's not a dud.?
On Sunday, March 6, 2022, 12:39:12 AM EST, John Gord via groups.io <johngord@...> wrote:
I had some success in repairing the switches on a couple of 6GHz 8753D's that I bought in known "parts" condition.? In both cases, an ESD protection diode in the switch had gone short circuit, presumably from either an ESD event or excess power.? I crudely removed the shorted diodes, and the switches worked, but did not meet the original uncorrected port match specifications.? They work well enough for me when corrections are on.? I put a note on each to warn whomever gets the units when the kids eventually clean out the lab.
--John Gord
On Sat, Mar 5, 2022 at 08:30 PM, Lothar baier wrote:
As far as repairing a bad switch goes it would depend on your capabilities ?? those switches are not build using regular surface mount parts , the switch uses a gold plated block that has channels machined , inside those channels you have GaAs Switch dies that are wire bonded and attached using solder or conductive epoxy , its not trivial to remove and replace the dies you need wire bonders and die attach machine and finding the correct die is a whole different story , its not trivial at all
?
?
?
Sent from for Windows
?
?
I switched the physical coupler (did not modification around the swtich). I just moved Port 2 into Port 1 position. I have not installed the other coupler yet, so Port 1 (as seen from the front of the instrument) has my old Port 2 Coupler in it. Port 2 is Blank.
On Saturday, March 5, 2022, 10:38:59 PM EST, Lothar baier <lothar@...> wrote:
Just to double check if I understand this correctly , did you swap the couplers or did you flip the switch ports and switch ?
?
Sent from for Windows
?
?
Just got done removing Port 2 Coupler and placing it in the Port 1 Position. Problem follows, so I think this is kind of pointing towards the switch. I can say for sure the source is providing the correct power at 3.0 GHz. Whatever it's producing above 3 GHz I can say for sure, but it is stable. No erratic behavior when switching between the ports.?
On Saturday, March 5, 2022, 09:24:07 PM EST, Rich Miller via groups.io <av8torrich@...> wrote:
I was not able to take those measurements prior to pulling it apart.. What I can state is; S22 was rock solid with no such fluctuations, and passes all test without issue. Furthermore, S22 never fluctuates when moving to another measurement and back again. When I did power up the 8753E, the S11 response is normal, and remains normal until such time as I switch between another measurement. As a matter of fact, simply hitting S11 multiple times will straighten the response out, and also cause the response to go nutty. In short, if I cycle S11 multiple times I can either get a normal RL response, or something similar to what I showed in my original post.
What I am attempting now, is swapping Port 1 with Port 2, and see if the problem follows. I have it down in my lab in the basement where I do have a small ESD work area near where I solder. Good news is, we are at >70% humidity here in the mid Atlantic today so that should help eliminate some of the ESD Risk.
¸é¾±³¦³ó¡
?
From your picture, the problem is above 3 GHz. The Source oscillator does a major band switch at about 3 GHz, which suggests that might be where the problem is. The SS switch ¡®could¡¯ be erratic, but it just doesn¡¯t seem likely, especially since you are not seeing any power level changes.
?
When you power up and just let it run for a while without changing anything, does it stay good?
?
If you put a through between ports 1 and 2, and look at S21and S12, what happens?
?
Also, does S22 behave properly? From your original post, I believe it must be OK, but I¡¯m double checking that conclusion.
?
One caution about cables. They can build up static charge between the center and outer, which dumps into the ports when? connected. Usually only a concern with long cables, but¡
?
?
I just got done measuring the power out at Port 1. To my surprise, I cannot detect any significant power output fulgurations. I have tried 3GHz, 3.707GHz (worse offender in S11 Response), 4GHz and 5GHz.? They all look very stable, when switching back and forth. I am using a power meter which is not rated for accuracy at 3 - 6 GHz, but I can set the output to 0dBm look at the measurement, and switch back and forth and look for any relative change. It is not fluctuating whatsoever.?
I also checked 3GHz with my MDO, and that is a accurate power measurement. Now I am scratching my head again.
On Saturday, March 5, 2022, 07:16:43 PM EST, Lothar baier <lothar@...> wrote:
Try to find a cheap working 85047A ,? it uses the same inerts as the 8753D/E/ES including the solid state switch and you get 2 couplers as added bonus .
?
Take one word of caution though ,? when handling the switch use a ESD mat and wriststrap or at least put some esd caps or terminations on the SMA connectors ,? those suckers are really sensitive to ESD
?
Sent from for Windows
?
?
Yes, I am leaning this way (switch being the issue). I think it could also be that I was running a bunch of two port calibrations using a Agilent 85093 this morning (testing eCal out). I had some averaging on, 1601 Points, and 300KHz of IF B/W Set. Needless to say there was a lot of switching going on today. Let me check the power output now, and then flip it over and pray that one of the connectors on the switch is loose.
Looks like the parts hunt is likely on!
On Saturday, March 5, 2022, 06:55:27 PM EST, Lothar baier <lothar@...> wrote:
The reversing switches are notorious for failures especially if a unit is used in a environment that is not ESD protected .? what you can also do and you have to be cautious if you do this is to remove the switch , remove the hardline from the switch to coupler port 1 and connect the coupler directly to the source , if your trace is consistent then you definatly have a bad switch !
?
?
Sent from for Windows
?
?
It just started failing Port 1 Test. I was doing this just as this email came in. It is failing it consistently. I do not have a power meter, but I can take a look with my Spectrum Analyzer to see if there are power fluctuations at 3GHz. This problem seems to focus at frequencies higher than 3GHz.?
Once I have a look at the output power, I will open and have a look. This is a new problem, as I never saw this before.
On Saturday, March 5, 2022, 06:38:56 PM EST, Lothar baier <lothar@...> wrote:
If the S11response changes when you switch back and forth than this would point towards a repeatability issue with the solid state switch the fact that this changes with temperature would also point towards this direction , so here are a few things to try :
?
- Connect a short to port 1 ,? go to the service menu there is a op check for port 1 and 2 , run the op check several time first for port 1 then port 2 then go back to port 1 and so on , see if it passes consistently or if there is a failure
- If you have a power meter connect it to port 1 , change the analyzer to CW and a frequency close to the upper end (3 or 6GHz), set power to 0dBm and then switch back and forth between S11 and S22 measurement and see if the power changes
- Open the unit and check the hardline connetions , make sure the nuts are tight
?
Sent from for Windows
?
I have an issue with S11 (Port 1). It showed it's head now that I am running two port calibrations, thus I have not detected it just yet. My hunch is I have a problem with the switch, but not the Bridge. Here is what I am observing:
1. Upon boot up I get a good/normal S11 RL Response into a good 50 Ohm Load. This Condition will persist until I do one of the steps below.
2. If I switch to Port 2 (i.e. S22 Measurement), and then back to Port 1 the S11 Response has gone nutty (See Attached Picture).?
3. I have noticed, that if I depress the S11 MEAS multiple times, the S11 RL Response returns to normal.?
4. If you look at the enclosed picture, I have captured what I refer to as a normal S11 response, which I saved to memory (Smooth), and what it looks like after pressing S11 again (Wild variations in response).
I have noticed there is a stark difference between instrument, cold and warm on S11. I do not however see this behavior our of any of the Port 2 Measurements regardless of temperature. Is there anywhere else this could be coming from other than the Solid State Switch, or am I way off base in my thinking here??
|
Would disabling the 80v source be a big deal ??
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
toggle quoted message
Show quoted text
Doug and all,
I just acquired one such unit (HP8904A), and indeed, it is exceptionally accurate. Its 10MHz internal reference measures at 4.1ppm off on my oven conditioned HP5328A, and the DC levels are almost as accurate as I can measure them with my Fluke 8840a (for instance, the 10V DC level reads at 10.0003V). AC amplitude levels read with my HP54522A are at 0.00000V off for the 0.1 and 1000Hz signal. Wherever I am seeing deviations, they are usually an order of magnitude less than the allowed tolerance.
Anyway, VERY impressed. This is a unit which, as far as I could put it together, was in a maintained lab until some part of 2020, but since has been on eBay at least twice. Funny thing is it's been last looked at by a metrology lab in my literal neighborhood, then spent these 1-2 years somewhere in AZ, then came back to the neighborhood in CA to join my herd.
Now, on to the issue at hand - I'm very interested in replacing the LCD with a hopefully far more legible unit. Can anyone indicate some clear directions, if available anywhere, and maybe LCD units to use for this? I've seen Doug's recommendation, but I'm a bit weary the shield doesn't seem to fit behind it. The other concern is with the 80V source for the old unit that seems to need a load of sorts to be happy.
Radu.
|
Doug and all,
I just acquired one such unit (HP8904A), and indeed, it is exceptionally accurate. Its 10MHz internal reference measures at 4.1ppm off on my oven conditioned HP5328A, and the DC levels are almost as accurate as I can measure them with my Fluke 8840a (for instance, the 10V DC level reads at 10.0003V). AC amplitude levels read with my HP54522A are at 0.00000V off for the 0.1 and 1000Hz signal. Wherever I am seeing deviations, they are usually an order of magnitude less than the allowed tolerance.?
Anyway, VERY impressed. This is a unit which, as far as I could put it together, was in a maintained lab until some part of 2020, but since has been on eBay at least twice. Funny thing is it's been last looked at by a metrology lab in my literal neighborhood, then spent these 1-2 years somewhere in AZ, then came back to the neighborhood in CA to join my herd.?
Now, on to the issue at hand - I'm very interested in replacing the LCD with a hopefully far more legible unit. Can anyone indicate some clear directions, if available anywhere, and maybe LCD units to use for this? I've seen Doug's recommendation, but I'm a bit weary the shield doesn't seem to fit behind it. The other concern is with the 80V source for the old unit that seems to need a load of sorts to be happy.
Radu.?
|
Re: Scoping the Power Rails [8566B]
So here is a thought. I would attack the REF UNLOCK first. Note that all the other PLLs depend on an output from the 100 MHz REF oscillator. It that has problems, anything associated with it (virtually everything) should be considered in doubt. You really should get a set of extenders. There used to be a guy on e-bay that would custom make them - don't see him advertizing now, but if you search past auctions you can probably find him. Another possibility would be to purchase an extender card that matched the height requirement but had more contacts and cut it down - the best choice would be one with more than 2x times the contacts needed and you could make two extenders from one card - the required connectors are available from Digiket, e-bay, and other sources. Extender cards are a MUST. Cheers! Bruce Quoting Jinxie <paul666@...>:
I just needed a bit of a refresher on PLLs from my notes of 40 years ago; I'd forgotten quite a lot.
Anyway, there's no access to any test points on A10A7 from the top side but I note on the opposite side where the PCB traces are visible there were a couple of tiny holes in the perspex sheet which I assume are there to permit one to stick the point of a probe through (with difficulty) and they were marked something like 500khz ref and 500khz divided so I assume on my model that's where one is supposed to measure the signals. However, on probing, both were intermittent and grossly distorted square waves so something's obviously not right there.
I was really struggling with the PDF schematic on my computer so printed out the A10 20/30 block diagram from the manual which makes things a lot clearer not having to flip from one page to another and lose where all the connections are going to and from!
|
Re: Scoping the Power Rails [8566B]
I just needed a bit of a refresher on PLLs from my notes of 40 years ago; I'd forgotten quite a lot.
Anyway, there's no access to any test points on A10A7 from the top side but I note on the opposite side where the PCB traces are visible there were a couple of tiny holes in the perspex sheet which I assume are there to permit one to stick the point of a probe through (with difficulty) and they were marked something like 500khz ref and 500khz divided so I assume on my model that's where one is supposed to measure the signals. However, on probing, both were intermittent and grossly distorted square waves so something's obviously not right there.
I was really struggling with the PDF schematic on my computer so printed out the A10 20/30 block diagram from the manual which makes things a lot clearer not having to flip from one page to another and lose where all the connections are going to and from!
|
Re: ?utf-8?q?_=5BHP-Agilent-Keysight-equipment=5D?= ESG-3000A LCD replacement
Hello Manfred,
I am not home now so I can't be more presice about the location of the transistor.? It is on the bottom side of the motherboard close to the front panel and is connected to TP602.? If you measure the voltage at TP602 while changing the cotrast, you should see the voltage change. If it does not change, then the transistor is bad.? The transistor is nothing special, it just regulates the DC voltage. See the service manual http://www.doe.carleton.ca/~nagui/labequip/synth/manuals/e4400335.pdf, page 72 of 335.? This will show a block diagram of the contrast regulator.? It is? very simple circuit.
Let me know if this helps.?
Tom
toggle quoted message
Show quoted text
On Monday, March 07, 2022 05:11 EST, "Manfred Hund (DL2IAO)" <manfred.hund@...> wrote: ? Hello Tom, did you have mir informations about the transistoe which could be blown? Don't find anything in the web.
Manfred
On Sat, Mar 5, 2022 at 04:48 PM, Tom B wrote:Hello Manfred, Good luck. The difference in the FW1 and FW is the polarity of the contrast bias.? If you put in the FW1 in the older model it will blow the transistor that supplies the contrast bias.? The later motherboard has jumpers to set the bias polarity. There is a long thread here where someone replaced the LCD in his ESG, see: Tom Bryan
N3AJA ? On 3/5/2022 10:17 AM, Manfred Hund (DL2IAO) wrote: Hello Tom, i do have exactly the same problem, no jumpers on the motherboard and a?DMF-51043NFU-FW1, that will not work. The original MDF-50562NFU-FW has stopped to work, so I need a new LCD. Did you have a solution for the problem already? Best regards Manfred
?
|
When I did it to my 5370A, I put in the "B" firmware, and it became a "B". It seemed significantly faster. The biggest issue I found is shutdowns. It is a bad idea to shutdown BBB linux systems by simply losing power. If I were going to do another spin on the board, I would include a battery, and a power fail sense circuit that sent a shutdown signal to the BBB. It has been a while, but as I recall, you can get all the data out through the network connection. Then it is very fast. -Chuck Harris On Mon, 7 Mar 2022 14:01:59 +0000 (UTC) "Bob Stewart" <bob@...> wrote: Yes, thanks!? I found it.? It works in kicad, and OshPark likes it.
So I just need to review it and order the boards.? I did have a
question though.? Does it allow for a faster throughput than the HP
boards, or do I still have to use the "fast binary output" mode for
higher throughput?
Bob
On Monday, March 7, 2022, 2:36:45 AM CST, Andy ZL3AG via
groups.io <zl3ag@...> wrote:
It's all there under the "pcb" subdir?
On 7/03/22 02:22, Chuck Harris wrote:
John is a friendly guy, I am sure that even if they aren't
on the github, he would release them.
-Chuck Harris
On Sun, 6 Mar 2022 06:57:37 +0000 (UTC) "Bob Stewart"
<bob@...> wrote:
Thanks Chuck!? I looked around for it, but I guess I missed it.
I'll check again.
Bob
? ? ? On Sunday, March 6, 2022, 12:35:59 AM CST, Chuck Harris
<cfharris@...> wrote:
? FYI, the board is pretty simple, and I think John Seamons has the
CAD files on his github.? If so, you could make your own for
about $40 plus the beaglebone.
-Chuck Harris
On Sun, 6 Mar 2022 06:15:18 +0000 (UTC) "Bob Stewart"
<bob@...> wrote:
I'm getting occasional ERR 7.5 from one of my 5370As.? I see that
the beaglebone board is history now.? So, do I have any options
for fixing this?
Bob
? ?
|
Yes, thanks!? I found it.? It works in kicad, and OshPark likes it.? So I just need to review it and order the boards.? I did have a question though.? Does it allow for a faster throughput than the HP boards, or do I still have to use the "fast binary output" mode for higher throughput?
On Monday, March 7, 2022, 2:36:45 AM CST, Andy ZL3AG via groups.io <zl3ag@...> wrote:
It's all there under the "pcb" subdir?
On 7/03/22 02:22, Chuck Harris wrote: > John is a friendly guy, I am sure that even if they aren't > on the github, he would release them. > > -Chuck Harris > > > On Sun, 6 Mar 2022 06:57:37 +0000 (UTC) "Bob Stewart" < bob@...> > wrote: >> Thanks Chuck!? I looked around for it, but I guess I missed it.? I'll >> check again. >> >> Bob >> >>? ? ? On Sunday, March 6, 2022, 12:35:59 AM CST, Chuck Harris >> < cfharris@...> wrote: >>? FYI, the board is pretty simple, and I think John Seamons has the >> CAD files on his github.? If so, you could make your own for >> about $40 plus the beaglebone. >> >> -Chuck Harris >> >> >> On Sun, 6 Mar 2022 06:15:18 +0000 (UTC) "Bob Stewart" < bob@...> >> wrote: >>> I'm getting occasional ERR 7.5 from one of my 5370As.? I see that >>> the beaglebone board is history now.? So, do I have any options for >>> fixing this? >>> >>> Bob >>> >>> >>> >>> >>> >> >> >> >> >> >> >>? ? >> >> >> >> >> > > > > > >
|
Re: Low EMI lighting for labs and work areas
Hello Radu.
Check the video cables as well.
I've had more than my fair share of "leaky" VGA cables in the past, where in one case, the "so called" 75 Ohm coax cables in the common jacket, were not much more than a twisted pair, where one side had a much larger layer of insulation than the other!?? It radiated video noise rather badly, and also distorted the image at high resolution too.
That one was a "Big Name" brand too, a very common one beginning with the second letter of the English alphabet...
The store (now gone) was not interested in refund etc, so I ordered a cheap cable from one of the usual websites, and all was quiet again.? For a fraction of the cost of the "Big Name" brand leaky feeder.
Though most "Modern" PC's and monitors are now connected via DVI or HDMI cables, I'd not be surprised if some of the suppliers of after-market cables, ship items that leak EMI as well.?? Just as some USB cables do!
Best Regards.
Dave G8KBV
--
Created on and sent from a Unix like PC running and using free and open source software:
|
Re: ESG-3000A LCD replacement
Hello Tom, did you have mir informations about the transistoe which could be blown? Don't find anything in the web.
Manfred
toggle quoted message
Show quoted text
On Sat, Mar 5, 2022 at 04:48 PM, Tom B wrote:
Hello Manfred,
Good luck. The difference in the FW1 and FW is the polarity of the contrast bias.? If you put in the FW1 in the older model it will blow the transistor that supplies the contrast bias.? The later motherboard has jumpers to set the bias polarity.
There is a long thread here where someone replaced the LCD in his ESG, see:
Tom Bryan
N3AJA
?
On 3/5/2022 10:17 AM, Manfred Hund (DL2IAO) wrote:
Hello Tom, i do have exactly the same problem, no jumpers on the motherboard and a?DMF-51043NFU-FW1, that will not work. The original MDF-50562NFU-FW has stopped to work, so I need a new LCD. Did you have a solution for the problem already? Best regards Manfred
|
It's all there under the "pcb" subdir?
toggle quoted message
Show quoted text
On 7/03/22 02:22, Chuck Harris wrote: John is a friendly guy, I am sure that even if they aren't
on the github, he would release them.
-Chuck Harris
On Sun, 6 Mar 2022 06:57:37 +0000 (UTC) "Bob Stewart" <bob@...>
wrote:
Thanks Chuck!? I looked around for it, but I guess I missed it.? I'll
check again.
Bob
On Sunday, March 6, 2022, 12:35:59 AM CST, Chuck Harris
<cfharris@...> wrote:
FYI, the board is pretty simple, and I think John Seamons has the
CAD files on his github.? If so, you could make your own for
about $40 plus the beaglebone.
-Chuck Harris
On Sun, 6 Mar 2022 06:15:18 +0000 (UTC) "Bob Stewart" <bob@...>
wrote:
I'm getting occasional ERR 7.5 from one of my 5370As.? I see that
the beaglebone board is history now.? So, do I have any options for
fixing this?
Bob
|
Re: HP-8753E S11 Intermittent Results - Switch or Bridge?
I am a RF Engineer working on designing and building RF and microwave circuits for over 24 years ,? I always clean the flux even if its ¡°no clean¡± blah blah because I have seen too much stuff with RF going on , I didn¡¯t with the 8753 at
first because its digital stuff and RF guys always laugh at digital after all its low frequency stuff so I was kinda surprised but it does make a difference and I can assure you I never used crappy solder
?
?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]>
On Behalf Of Rich Miller via groups.io
Sent: Sunday, March 6, 2022 10:03 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP-8753E S11 Intermittent Results - Switch or Bridge?
?
Yeah, I doubt that to be the case here. I graduated Navy Micro Miniature Repair School in the 90¡¯s, and a PLCC is, ¡°no thing but a chicken wing¡± compared to what I have dealt with in the past. I have inspected this EEPROM under the microscope
there is no flux, and if there were I do not use the typical, pine pitch based flux in any of the work I do. In theory you could leave the paste I use on without cleaning, but I clean anyways.
I actually prefer UltraSolve to IPA. Expensive, but worth it!
Rich?
On Mar 6, 2022, at 10:55 PM, Lothar baier <Lothar@...> wrote:
?
Aaaaaah ?now I see
??
I learned this the hard way back when I hacked Options on the 8753 and 8720 units ,? you have to be VERY CAUTIOUS when you desolder and resolder the EEPROM , the flux from the soldering can create problems that can manifest themselves in
different ways including corrupted cal contants ( well not really corrupted but the CPU reads wrong values ) after you remove the prom you have to clean the board area and the part from all flux residue , I did this using 99% IPA and surgical swabs ,? once
you solder the part back in remove any flux as well
?
?
On Sunday, March 6, 2022, 10:41:30 PM EST, Lothar baier <lothar@...> wrote:
Did you desolder the EEPROM ?
?
?
I have the EEPROM Binaries copied and stored for this VNA. I am leaning towards the fact this is not a corruption of EEPROM Cal Constants.
Based on my recent findings, the switch is looking more like the culprit here.
On Sunday, March 6, 2022, 06:44:14 PM EST, Lothar baier <lothar@...>
wrote:
EEPROMs sometimes get corrupted which is why agilent provided a backup disk
?
The problem with the EEPROM is that if it goes bad you cant just order one from mouser or digi key and pop it in
, the agilent part is preprogrammed with certain information if you put in a blank the CPU wont boot
?
?
Actually the uncorrected response looks almost better than what I had been running. I do have a backup of the EEPROM
which I took from the instrument prior to my repair attempts. I am going to try and load this, see if that helps. I was looking at the test you describe, and quickly realized a power meter with GPIB interface may have to happen sooner than I had planned.?
Wonder how they all of a sudden became corrupted?? Ohh well, I think this troubleshooting is fun so I cant complain
too much.
On Sunday, March 6, 2022, 01:38:34 PM EST, Lothar baier <lothar@...>
wrote:
If this is the case than there is a chance that your correction constants are corrupted , you pretty much need to run TEST 53 which re-establishes the sampler correction constants BUT
in order to run this test you need a power meter and sensor there is no way around it unless you have the backup disk for the EEPROM which originally was supplied with the unit !
?
If you get a meter and run the test I recommend you run tests 44/45/46/48 first , don¡¯t forget to move the write protect jumper on the CPU board and let the unit warm up about 1hr before
running the tests , once those tests are done run 53 and then get a floppy and back up your corrections just in case
?
Sent from
for Windows
?
New Hint - Last night I saw a mention of turning off the Sampler Cor Factors OFF.? I just did this, and now the
problem is gone the VNA passes Port 1 Test at least 10 times now..? Wow, it could be a sampler, or a sampler alignment problem.?
On Sunday, March 6, 2022, 11:10:57 AM EST, Rich Miller via groups.io <av8torrich@...>
wrote:
That was a good warning!? Yes my A5 Sampler is a part number 5087-7001. My donor unit only has P/N 5087-7000. The
donor unit was an OPT11, which may explain the difference in Samplers. I would not have caught that one right away!
On Sunday, March 6, 2022, 11:04:59 AM EST, Lothar baier <lothar@...>
wrote:
A few comments on this , I have hardly ever seen any issues with the signal processing past the sampler , as far as changing the sampler keep in mind that the R and A,B channels use
a different part number so pay attention ,? also I want to point out that changing the sampler will require you to run the sampler adjustment tests
?
Sent from
for Windows
?
?
I checked all the cables around A5 which is the Sampler attached to Port 1. These all look good physically. I am unable to change the response by moving them or shaking them. Next,
I will remove the A5 Sampler and replace it. After looking at block diagram provided in the service manual (not great for troubleshooting), I will not attempt the removal/replacement of the A11 board. It seems to me, that if there was a problem beyond the
sampler, I would expect to see an alarming result on Port 2 if the A11 board were bad. If I am wrong on this, please advise.?
I think you can just move the cables that connect the couplers to the samplers without having to move hardware around.
?
?
I think I confused everyone, sorry!?
What I have done now is swapped both couplers. The problem stays does not follow. It is something in the Port 1 line beyond the coupler. I do have extra samplers here, I suppose no
harm in trying it.?
I should note, I am now seeing these wild results below 3GHz, but nowhere as bad as I see it above 3GHz. 4 - 5 GHz is where it's most consistently bad.
Let me take a look at the service manual, and determine which sampler I need to swap. Would be nice if that were the issue!
Agreed, but does the switch ¡®know¡¯ about the band change? That¡¯s what is curious here.
?
¸é¾±³¦³ó¡You said that the problem follows. Do you mean that the problem still occurs with the port 2 coupler? So it did not follow the coupler, but remained on the port 1 side.
?
I wonder if it is a sampler problem instead. Maybe a bad cable from the coupler to the sampler, or from the sampler to the A/D?
?
There is also a clue in that it stays OK when first turned on, until it is actually switched.
?
?
You are correct about the source switching above 3GHz BUT nothing changes at the source if you switch between S11 and S22 , if you have a source issue than its almost always symmetrical
which means it appears on S11 and S22 .
The Switch is a solid state switch that is a cascade of multiple cells to increase isolation , each branch has ESD protection diodes which are supposed to protect the switch cells from
ESD if those diodes get damaged the effects appear most significant at higher frequencies than at lower ones first S11 and/or S22 of the switch also degrades which affects the source operation asymmetrical !
?
Sent from
for Windows
?
?
¸é¾±³¦³ó¡
?
From your picture, the problem is above 3 GHz. The Source oscillator does a major band switch at about 3 GHz, which suggests that might be where the problem is. The SS switch ¡®could¡¯
be erratic, but it just doesn¡¯t seem likely, especially since you are not seeing any power level changes.
?
When you power up and just let it run for a while without changing anything, does it stay good?
?
If you put a through between ports 1 and 2, and look at S21and S12, what happens?
?
Also, does S22 behave properly? From your original post, I believe it must be OK, but I¡¯m double checking that conclusion.
?
One caution about cables. They can build up static charge between the center and outer, which dumps into the ports when? connected. Usually only a concern with long cables, but¡
?
?
I just got done measuring the power out at Port 1. To my surprise, I cannot detect any significant power output fulgurations. I have tried 3GHz, 3.707GHz (worse offender in S11 Response),
4GHz and 5GHz.? They all look very stable, when switching back and forth. I am using a power meter which is not rated for accuracy at 3 - 6 GHz, but I can set the output to 0dBm look at the measurement, and switch back and forth and look for any relative change.
It is not fluctuating whatsoever.?
I also checked 3GHz with my MDO, and that is a accurate power measurement. Now I am scratching my head again.
On Saturday, March 5, 2022, 07:16:43 PM EST, Lothar baier <lothar@...> wrote:
Try to find a cheap working 85047A ,? it uses the same inerts as the 8753D/E/ES including the solid state switch and you get 2 couplers as added bonus .
?
Take one word of caution though ,? when handling the switch use a ESD mat and wriststrap or at least put some esd caps or terminations on the SMA connectors ,? those suckers are really
sensitive to ESD
?
Sent from
for Windows
?
Yes, I am leaning this way (switch being the issue). I think it could also be that I was running a bunch of two port calibrations using a Agilent 85093 this morning (testing eCal out).
I had some averaging on, 1601 Points, and 300KHz of IF B/W Set. Needless to say there was a lot of switching going on today. Let me check the power output now, and then flip it over and pray that one of the connectors on the switch is loose.
Looks like the parts hunt is likely on!
On Saturday, March 5, 2022, 06:55:27 PM EST, Lothar baier <lothar@...> wrote:
The reversing switches are notorious for failures especially if a unit is used in a environment that is not ESD protected .? what you can also do and you have to be cautious if you
do this is to remove the switch , remove the hardline from the switch to coupler port 1 and connect the coupler directly to the source , if your trace is consistent then you definatly have a bad switch !
?
?
Sent from
for Windows
?
?
It just started failing Port 1 Test. I was doing this just as this email came in. It is failing it consistently. I do not have a power meter, but I can take a look with my Spectrum
Analyzer to see if there are power fluctuations at 3GHz. This problem seems to focus at frequencies higher than 3GHz.?
Once I have a look at the output power, I will open and have a look. This is a new problem, as I never saw this before.
On Saturday, March 5, 2022, 06:38:56 PM EST, Lothar baier <lothar@...> wrote:
If the S11response changes when you switch back and forth than this would point towards a repeatability issue with the solid state switch the fact that this changes with temperature
would also point towards this direction , so here are a few things to try :
?
-
Connect a short to port 1 ,? go to the service menu there is a op check for port 1 and 2 , run the op check several time first for port 1 then port 2 then go back to port 1 and so on , see if it
passes consistently or if there is a failure
-
If you have a power meter connect it to port 1 , change the analyzer to CW and a frequency close to the upper end (3 or 6GHz), set power to 0dBm and then switch back and forth between S11 and S22
measurement and see if the power changes
-
Open the unit and check the hardline connetions , make sure the nuts are tight
?
Sent from
for Windows
?
I have an issue with S11 (Port 1). It showed it's head now that I am running two port calibrations, thus I have not detected it just yet. My hunch is I have a problem with the switch,
but not the Bridge. Here is what I am observing:
1. Upon boot up I get a good/normal S11 RL Response into a good 50 Ohm Load. This Condition will persist until I do one of the steps below.
2. If I switch to Port 2 (i.e. S22 Measurement), and then back to Port 1 the S11 Response has gone nutty (See Attached Picture).?
3. I have noticed, that if I depress the S11 MEAS multiple times, the S11 RL Response returns to normal.?
4. If you look at the enclosed picture, I have captured what I refer to as a normal S11 response, which I saved to memory (Smooth), and what it looks like after pressing S11 again (Wild
variations in response).
I have noticed there is a stark difference between instrument, cold and warm on S11. I do not however see this behavior our of any of the Port 2 Measurements regardless of temperature.
Is there anywhere else this could be coming from other than the Solid State Switch, or am I way off base in my thinking here??
|
Re: HP-8753E S11 Intermittent Results - Switch or Bridge?
Yeah, I doubt that to be the case here. I graduated Navy Micro Miniature Repair School in the 90¡¯s, and a PLCC is, ¡°no thing but a chicken wing¡± compared to what I have dealt with in the past. I have inspected this EEPROM under the microscope there is no flux, and if there were I do not use the typical, pine pitch based flux in any of the work I do. In theory you could leave the paste I use on without cleaning, but I clean anyways.
I actually prefer UltraSolve to IPA. Expensive, but worth it!
toggle quoted message
Show quoted text
On Mar 6, 2022, at 10:55 PM, Lothar baier <Lothar@...> wrote:
?
Aaaaaah ?now I see
??
I learned this the hard way back when I hacked Options on the 8753 and 8720 units ,? you have to be VERY CAUTIOUS when you desolder and resolder the EEPROM , the flux from the soldering can create problems that can manifest themselves in
different ways including corrupted cal contants ( well not really corrupted but the CPU reads wrong values ) after you remove the prom you have to clean the board area and the part from all flux residue , I did this using 99% IPA and surgical swabs ,? once
you solder the part back in remove any flux as well
?
?
On Sunday, March 6, 2022, 10:41:30 PM EST, Lothar baier <lothar@...> wrote:
Did you desolder the EEPROM ?
?
?
I have the EEPROM Binaries copied and stored for this VNA. I am leaning towards the fact this is not a corruption of EEPROM Cal Constants.
Based on my recent findings, the switch is looking more like the culprit here.
On Sunday, March 6, 2022, 06:44:14 PM EST, Lothar baier <lothar@...>
wrote:
EEPROMs sometimes get corrupted which is why agilent provided a backup disk
?
The problem with the EEPROM is that if it goes bad you cant just order one from mouser or digi key and pop it in
, the agilent part is preprogrammed with certain information if you put in a blank the CPU wont boot
?
?
Actually the uncorrected response looks almost better than what I had been running. I do have a backup of the EEPROM
which I took from the instrument prior to my repair attempts. I am going to try and load this, see if that helps. I was looking at the test you describe, and quickly realized a power meter with GPIB interface may have to happen sooner than I had planned.?
Wonder how they all of a sudden became corrupted?? Ohh well, I think this troubleshooting is fun so I cant complain
too much.
On Sunday, March 6, 2022, 01:38:34 PM EST, Lothar baier <lothar@...>
wrote:
If this is the case than there is a chance that your correction constants are corrupted , you pretty much need to run TEST 53 which re-establishes the sampler correction constants BUT
in order to run this test you need a power meter and sensor there is no way around it unless you have the backup disk for the EEPROM which originally was supplied with the unit !
?
If you get a meter and run the test I recommend you run tests 44/45/46/48 first , don¡¯t forget to move the write protect jumper on the CPU board and let the unit warm up about 1hr before
running the tests , once those tests are done run 53 and then get a floppy and back up your corrections just in case
?
Sent from
for Windows
?
New Hint - Last night I saw a mention of turning off the Sampler Cor Factors OFF.? I just did this, and now the
problem is gone the VNA passes Port 1 Test at least 10 times now..? Wow, it could be a sampler, or a sampler alignment problem.?
On Sunday, March 6, 2022, 11:10:57 AM EST, Rich Miller via groups.io <av8torrich@...>
wrote:
That was a good warning!? Yes my A5 Sampler is a part number 5087-7001. My donor unit only has P/N 5087-7000. The
donor unit was an OPT11, which may explain the difference in Samplers. I would not have caught that one right away!
On Sunday, March 6, 2022, 11:04:59 AM EST, Lothar baier <lothar@...>
wrote:
A few comments on this , I have hardly ever seen any issues with the signal processing past the sampler , as far as changing the sampler keep in mind that the R and A,B channels use
a different part number so pay attention ,? also I want to point out that changing the sampler will require you to run the sampler adjustment tests
?
Sent from
for Windows
?
?
I checked all the cables around A5 which is the Sampler attached to Port 1. These all look good physically. I am unable to change the response by moving them or shaking them. Next,
I will remove the A5 Sampler and replace it. After looking at block diagram provided in the service manual (not great for troubleshooting), I will not attempt the removal/replacement of the A11 board. It seems to me, that if there was a problem beyond the
sampler, I would expect to see an alarming result on Port 2 if the A11 board were bad. If I am wrong on this, please advise.?
I think you can just move the cables that connect the couplers to the samplers without having to move hardware around.
?
?
I think I confused everyone, sorry!?
What I have done now is swapped both couplers. The problem stays does not follow. It is something in the Port 1 line beyond the coupler. I do have extra samplers here, I suppose no
harm in trying it.?
I should note, I am now seeing these wild results below 3GHz, but nowhere as bad as I see it above 3GHz. 4 - 5 GHz is where it's most consistently bad.
Let me take a look at the service manual, and determine which sampler I need to swap. Would be nice if that were the issue!
Agreed, but does the switch ¡®know¡¯ about the band change? That¡¯s what is curious here.
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¸é¾±³¦³ó¡You said that the problem follows. Do you mean that the problem still occurs with the port 2 coupler? So it did not follow the coupler, but remained on the port 1 side.
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I wonder if it is a sampler problem instead. Maybe a bad cable from the coupler to the sampler, or from the sampler to the A/D?
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There is also a clue in that it stays OK when first turned on, until it is actually switched.
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You are correct about the source switching above 3GHz BUT nothing changes at the source if you switch between S11 and S22 , if you have a source issue than its almost always symmetrical
which means it appears on S11 and S22 .
The Switch is a solid state switch that is a cascade of multiple cells to increase isolation , each branch has ESD protection diodes which are supposed to protect the switch cells from
ESD if those diodes get damaged the effects appear most significant at higher frequencies than at lower ones first S11 and/or S22 of the switch also degrades which affects the source operation asymmetrical !
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¸é¾±³¦³ó¡
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From your picture, the problem is above 3 GHz. The Source oscillator does a major band switch at about 3 GHz, which suggests that might be where the problem is. The SS switch ¡®could¡¯
be erratic, but it just doesn¡¯t seem likely, especially since you are not seeing any power level changes.
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When you power up and just let it run for a while without changing anything, does it stay good?
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If you put a through between ports 1 and 2, and look at S21and S12, what happens?
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Also, does S22 behave properly? From your original post, I believe it must be OK, but I¡¯m double checking that conclusion.
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One caution about cables. They can build up static charge between the center and outer, which dumps into the ports when? connected. Usually only a concern with long cables, but¡
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I just got done measuring the power out at Port 1. To my surprise, I cannot detect any significant power output fulgurations. I have tried 3GHz, 3.707GHz (worse offender in S11 Response),
4GHz and 5GHz.? They all look very stable, when switching back and forth. I am using a power meter which is not rated for accuracy at 3 - 6 GHz, but I can set the output to 0dBm look at the measurement, and switch back and forth and look for any relative change.
It is not fluctuating whatsoever.?
I also checked 3GHz with my MDO, and that is a accurate power measurement. Now I am scratching my head again.
On Saturday, March 5, 2022, 07:16:43 PM EST, Lothar baier <lothar@...> wrote:
Try to find a cheap working 85047A ,? it uses the same inerts as the 8753D/E/ES including the solid state switch and you get 2 couplers as added bonus .
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Take one word of caution though ,? when handling the switch use a ESD mat and wriststrap or at least put some esd caps or terminations on the SMA connectors ,? those suckers are really
sensitive to ESD
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Yes, I am leaning this way (switch being the issue). I think it could also be that I was running a bunch of two port calibrations using a Agilent 85093 this morning (testing eCal out).
I had some averaging on, 1601 Points, and 300KHz of IF B/W Set. Needless to say there was a lot of switching going on today. Let me check the power output now, and then flip it over and pray that one of the connectors on the switch is loose.
Looks like the parts hunt is likely on!
On Saturday, March 5, 2022, 06:55:27 PM EST, Lothar baier <lothar@...> wrote:
The reversing switches are notorious for failures especially if a unit is used in a environment that is not ESD protected .? what you can also do and you have to be cautious if you
do this is to remove the switch , remove the hardline from the switch to coupler port 1 and connect the coupler directly to the source , if your trace is consistent then you definatly have a bad switch !
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It just started failing Port 1 Test. I was doing this just as this email came in. It is failing it consistently. I do not have a power meter, but I can take a look with my Spectrum
Analyzer to see if there are power fluctuations at 3GHz. This problem seems to focus at frequencies higher than 3GHz.?
Once I have a look at the output power, I will open and have a look. This is a new problem, as I never saw this before.
On Saturday, March 5, 2022, 06:38:56 PM EST, Lothar baier <lothar@...> wrote:
If the S11response changes when you switch back and forth than this would point towards a repeatability issue with the solid state switch the fact that this changes with temperature
would also point towards this direction , so here are a few things to try :
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Connect a short to port 1 ,? go to the service menu there is a op check for port 1 and 2 , run the op check several time first for port 1 then port 2 then go back to port 1 and so on , see if it
passes consistently or if there is a failure
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If you have a power meter connect it to port 1 , change the analyzer to CW and a frequency close to the upper end (3 or 6GHz), set power to 0dBm and then switch back and forth between S11 and S22
measurement and see if the power changes
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Open the unit and check the hardline connetions , make sure the nuts are tight
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I have an issue with S11 (Port 1). It showed it's head now that I am running two port calibrations, thus I have not detected it just yet. My hunch is I have a problem with the switch,
but not the Bridge. Here is what I am observing:
1. Upon boot up I get a good/normal S11 RL Response into a good 50 Ohm Load. This Condition will persist until I do one of the steps below.
2. If I switch to Port 2 (i.e. S22 Measurement), and then back to Port 1 the S11 Response has gone nutty (See Attached Picture).?
3. I have noticed, that if I depress the S11 MEAS multiple times, the S11 RL Response returns to normal.?
4. If you look at the enclosed picture, I have captured what I refer to as a normal S11 response, which I saved to memory (Smooth), and what it looks like after pressing S11 again (Wild
variations in response).
I have noticed there is a stark difference between instrument, cold and warm on S11. I do not however see this behavior our of any of the Port 2 Measurements regardless of temperature.
Is there anywhere else this could be coming from other than the Solid State Switch, or am I way off base in my thinking here??
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Jinxie