Re: Scoping the Power Rails [8566B]
That's what I was thinking.? A ferrite bead is an inductor that is purposefully made to be lossy.? It absorbs high frequency energy while passing DC and low frequency energy.
Assuming the probe cable can be bent into loops without damage, you're probably onto something, John.
Jim Ford
Sent from my T-Mobile 4G LTE Device
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-------- Original message -------- From: "John Gord via groups.io" <johngord@...> Date: 2/27/22 4:32 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] Scoping the Power Rails [8566B]
Dave, Adding ferrite beads to the ground lead itself will probably make things worse.?? However, threading the entire probe cable several times through a large ferrite can often help reduce noise due to ground differences between the oscilloscope and the unit under test.? A large, short, separate ground strap between the chassis of the two units also helps. The "ferrite-turns-on-the-probe-cable" method was shown to me by a designer of multi-kilowatt vehicle drive inverters. --John Gord On Sun, Feb 27, 2022 at 02:05 PM, Dave McGuire wrote:
You could try slipping a few ferrite beads on the probe's ground
lead. I'm not sure that'd help, but it might; does anyone else have any
thoughts on that?
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
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Re: OT: Help with Galep-5 problems
I’m still hoping someone will be able do this test for me.?? I’m trying to establish if this just my Galep-5 or if others have the same issue. ? Why?? Because this is the 2nd. Galep-5 I’ve had in my hands and both behaved in exactly the same way when trying to read M27C4001. ? David ?
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From: [email protected] <[email protected]> On Behalf Of davebb123456
Sent: 26 February 2022 18:56
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] OT: Help with Galep-5 problems? Sorry I have just read it again , I only had a problem with programming, I do not have this programmer ? Hi folks,
I just bought a Galep-5 and it is failing to read or verify M27C4001 EPROMS.
This is the second Galep-5 I've bought and the first one also refused to
work with M27C4001 EPROMS (and had some other issues so it went back).
So if you have a Galep-5 and some M27C4001 EPROMs, please could I ask you
try to get it to read or verify them for me and let me know what happens.
I get "Error !" and "Verify failure !" for verify
For a read I get this if the continuity test is enabled:
? ? ? ? Doing Continuity Test
? ? ? ? Galep disconnect dectected.
? ? ? ? ==> cAlgoModManager::PostActionFkt():Error #1
? ? ? ? ==> cAlgoModManager::PostActionFkt():Error #2
? ? ? ? Error: Algo Data read back #1
? ? ? ? Action aborted!
or this if the continuity test is disabled:
? ? ? ? Continuity Test disabled
? ? ? ? Load FPGA(s) with HDW OK.
? ? ? ? Error !
? ? ? ? Read failed !
Cheers, David
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Re: Scoping the Power Rails [8566B]
For what it's worth. Here was my problem 
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Re: Scoping the Power Rails [8566B]
Ah ok, thanks for this info! I've made a note of this.
-Dave
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On 2/27/22 19:32, John Gord via groups.io wrote: Dave,
Adding ferrite beads to the ground lead itself will probably make things worse.
However, threading the entire probe cable several times through a large ferrite can often help reduce noise due to ground differences between the oscilloscope and the unit under test.? A large, short, separate ground strap between the chassis of the two units also helps.
The "ferrite-turns-on-the-probe-cable" method was shown to me by a designer of multi-kilowatt vehicle drive inverters.
--John Gord
On Sun, Feb 27, 2022 at 02:05 PM, Dave McGuire wrote:
You could try slipping a few ferrite beads on the probe's ground
lead. I'm not sure that'd help, but it might; does anyone else have any
thoughts on that?
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
--
Dave McGuire, AK4HZ
New Kensington, PA
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Re: Scoping the Power Rails [8566B]
I've be watching this chain with someinterest. The thing that occurs to me is why are we all helping him go down the rabbit hole?
I've owned or worked on something like 25 8566 A and B instruments, many with unlock problems and never seen a case in which low level power supply noise caused unlock - in might aggravate the problem but never seen anything like the noise discussed affecting YO Lock If the voltages are within 5% the power supply is unlikely the problem.
Here are some questions that should ve asked (Forgive me if they have already been asked)
1) Are the loops MN and 20/30 subsections all locked?
2) Is the YO loop locked (There is a green LED on the YO loop interconnect board - all lock indicator are visible with the cover removed - no other disassembly required).
3) Does the Unlock message appear at all frequencies (Set scan width to 0 and use RPG to vary center frequency - see if loop as always unlocked or if sometimes it locks)
4) Have you used the frequency diagnostics and measured the YIG output frequency and power? (somm dissesembly required)
5) IMO, If all the LEDS in the M/N and 20/30 sections are lit and the YO LED is not, suspect the coupler (directly on top of the YO interconnect board.
6) Assuming M/N and 20/30 are OK, it would be a good idea to check the voltages AT the YO interconnect board before starting any disassembly.
7) It would also be a good idea to confirm the M/N, 20/30, and YIG frequencies (available using the front panel frequency diagnostic) before resorting to disassembly.
Unlock problems are generally relatively simple to tack down if you follow the procedure in the diagnostics section.
IMO using a scope on the DC rails can be problematic for exactly the reason you are having problems - I generally use a good RMS voltmeter to confirm PS ripple -there is a lot of noise floating around the environment and separating real from induced can, as you are finding out, can be a difficult problem. One thing you might do to eliminate chassis ground problems is to use the ground on the sweep card (forgotten wheather it is the sweep control or YIG driver, but one of them has a connection to the backplane ground plane and doesnot require connection to the chassis.
My 2 cents worth and I'll defer to Don B if he cares to comment because he has had WAY MORE experience than I have.
Cheers!
Bruce
Quoting Matt Huszagh <huszaghmatt@...>:
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On Sun, Feb 27, 2022 at 07:49 AM, Dave McGuire wrote:
As Harke said a few minutes ago, look at probe grounding. This is
often dismissed as one of those "That can't happen!" things, but it's a
very common and widely-misunderstood problem.
Always connect your probe's ground as close to the monitored circuit
node as possible, and keep the probe's ground wire as short as possible.
Jinxie,
Your spikes do sound a lot like what you'd see from excessive probing inductance caused by a large loop area from the ground lead. One simple test I often do to determine whether my probing is creating high-frequency content in the measured signal is to manually decrease the loop area by pushing the ground lead wire up against the oscilloscope probe body (basically, you want to minimize the area created by the main part of the probe and ground lead). If this decreases the amplitude of the spikes, that's a good indication that the high-frequency content is a result of poor probing and not a signal present in the DUT.
Matt
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Re: Scoping the Power Rails [8566B]
Dave,
Adding ferrite beads to the ground lead itself will probably make things worse.??
However, threading the entire probe cable several times through a large ferrite can often help reduce noise due to ground differences between the oscilloscope and the unit under test.? A large, short, separate ground strap between the chassis of the two units also helps.
The "ferrite-turns-on-the-probe-cable" method was shown to me by a designer of multi-kilowatt vehicle drive inverters.
--John Gord
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On Sun, Feb 27, 2022 at 02:05 PM, Dave McGuire wrote:
You could try slipping a few ferrite beads on the probe's ground
lead. I'm not sure that'd help, but it might; does anyone else have any
thoughts on that?
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
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Re: Scoping the Power Rails [8566B]
Many thanks, guys. Seems like the consensus is to look into the ground issues. It's getting very late in my part of the world right now so I shall retire and take a fresh look at these things Tuesday (as I'm busy all day Monday). I'll let y'all know how it goes.....
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Re: HP8903B - Plotting from HP-IB
OK, found: pressing the right mouse button a menu appears with also the item to delete the track.
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Re: Scoping the Power Rails [8566B]
First, make sure that you don’t have any ground loops.? I suggest you to power the 8566 and your scope from the same outlet.? ? Best, Francesco K5URG ?
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From: [email protected] < [email protected]> On Behalf Of Jinxie Sent: Sunday, February 27, 2022 4:00 PM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] Scoping the Power Rails [8566B] ? Okay, that's all understood now and thanks for the clarification, guys.
In order to properly eliminate the possibility of these spikes being a red herring I'm going to have to get creative with the probe grounding, clearly. This is where an extender board would be really useful. What a pity I don't have one!
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How does R1 act as a fuse in the HP 3048A option K23 DC Blocking Filter?
I'm looking at the schematic for the HP 3048A option K23 DC blocking
filter. I've attached a simplified version of this schematic for
convenience. Note that I've omitted the circuitry related to reverse
polarity (switch and diode protection). But, I don't need that to
address my question.
The manual states that the 51.1ohm R1 acts as a fuse protecting the DC
blocking filter (C3-16) from a large input DC voltage (K23 is rated for
+/- 30 V). C3-16 are rated for 50 VDC. How does this fuse action work
and how can we ensure it's reliable?
The description of R1 in the manual is:
RESISTOR 51.1 1% .05W TF TC=0+-100
I believe TF stands for thin film. So, the power rating of the resistor
is pretty low. Maybe that gives a hint. There's no DC current path
through R1. But, the startup ramp of a DC voltage is AC. Broadly, it
seems like we need to identify the scenario(s) in which there is a
voltage across R1 creating a short-duration power dissipation that
greatly exceeds R1's power rating. Because there's no DC current path,
we need to rely on a large, short-duration excess of power rather than a
steady excess of power to blow R1.
Current can either flow through C1 or L1 out of R1. C1 will present a
low impedance, but only at high frequencies (|Z_R1|=|Z_C1| at
663MHz). L1 will slow the voltage rise across C3-16. Presumably, the
goal is for R1 to blow open before the voltage across C3-16 exceeds the
voltage rating. If I make the initial ramp rate very fast I can greatly
exceed the 1.6V R1 rating, but only for a very short time. How can I be
sure to destroy the resistor? And, if I destroy it, how can I be sure it
will blow open? The NASA reliability design handbook (MIL-HDBK-338B)
gives the failure mode distribution for film resistors as (p. 7-198):
| failure mode | probability |
| <l> | <c> |
|------------------+-------------|
| open | 0.59 |
| parameter change | 0.36 |
| short | 0.05 |
Wouldn't it be easy to bypass the protection and exceed the capacitor's
voltage rating by supplying a ramp that's just slow enough that C1 looks
like a high-impedance?
There's a limiter across the output, but no proper fuse to blow if one
of these diodes starts to conduct. It seems like the 11848 or 3561 input
is pretty exposed in this case.
Thoughts? Maybe R1 isn't just a normal resistor?
Thanks
Matt
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Re: Boot Diskette HP1650/1651
On 2022-02-27 17:40, Bill Weinel wrote: All,
I am in dire need of a boot diskette for an HP 1650/1651 Logic Analyzer (Rev. 1.00) which I have restored. I have (so far) been unsuccessful in finding one. Should anyone have one to spare or know where one may be found, please drop me an email off the list. Many thanks in advance.
All the best,
Bill
Diskette images may be found at
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Re: HP-8753E Reading HPGL Files
All:
While going through the Firmware Revision notes, I found an interesting entry on Version 7.66 of the firmware:
- Added ripple limit and bandwidth limit tests
- Added JPEG and CSV (Comma Separated Values) file format
If reading the manual alone, this was not clear at all. I have enclosed a copy of what a typical .jpg file looks out of the VNA directly. To access this feature I did the following steps.
- SAVE/RECALL? - SAVE FILE FORMATS - Graph Format = JPG - Filetype = Graphic - Save File
Hope this saves someone else sometime.?
Rich? 
On Sunday, February 27, 2022, 04:21:05 PM EST, Rich Miller via groups.io <av8torrich@...> wrote:
I am now editing those files inside of the 7470 emulator. I have also been able query the VNA at Address 16 for them using this toolkit. Looks like I can choose from a great many formats besides .bmp to save these files. In the past, I had always used the emulator to seek plots directly from the machine. I never knew it could convert these files into various formats.?
Rich?
On Sunday, February 27, 2022, 04:15:46 PM EST, nj902 <wb0emu@...> wrote:
John's 7470 program will render an HPGL file which you can capture as a .BMP file and then tweak in your computer such as to add a box border.
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Re: Scoping the Power Rails [8566B]
If the spikes are at line frequency, then I'd suggest turning off
LED or Fluorescent lamps and see if it makes a difference.?
You could always remove the ground wire, and use the probe as a
sniffer to see if the radiation is more obvious at any place in
the equipment.? Or shop, for that matter.
an experiment would be to wrap the ground line around the probe
body and then ground the tip.
Another might be to wrap the probe (with grounded tip) in the old
standard aluminum foil, that may or may not tell you something.
If, of course, you put a shorting plug on the scope's input
instead of a probe and still get those spikes, that tells you
something quite different.
Harvey
On 2/27/2022 4:59 PM, Jinxie wrote:
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Okay, that's all understood now and thanks for the clarification,
guys.
In order to properly eliminate the possibility of these spikes
being a red herring I'm going to have to get creative with the
probe grounding, clearly. This is where an extender board would be
really useful. What a pity I don't have one!
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Re: Scoping the Power Rails [8566B]
On 2/27/22 16:59, Jinxie wrote: Okay, that's all understood now and thanks for the clarification, guys.
In order to properly eliminate the possibility of these spikes being a red herring I'm going to have to get creative with the probe grounding, clearly. This is where an extender board would be really useful. What a pity I don't have one! You could try slipping a few ferrite beads on the probe's ground lead. I'm not sure that'd help, but it might; does anyone else have any thoughts on that? -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: Scoping the Power Rails [8566B]
Okay, that's all understood now and thanks for the clarification, guys.
In order to properly eliminate the possibility of these spikes being a red herring I'm going to have to get creative with the probe grounding, clearly. This is where an extender board would be really useful. What a pity I don't have one!
|
Re: Boot Diskette HP1650/1651
On Sun, Feb 27, 2022 at 1:40 PM Bill Weinel <tube.radio@...> wrote:
All,
I am in dire need of a boot diskette for an HP 1650/1651 Logic Analyzer
(Rev. 1.00) which I have restored. I have (so far) been unsuccessful in
finding one. Should anyone have one to spare or know where one may be
found, please drop me an email off the list. Many thanks in advance.
If you have a PC with a 3.5-inch floppy drive that you can set up to boot into real mode DOS to create floppies from ImageDisk images, there are some 1650A disk images here:
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Re: HP instruments with stereo FM composite signal output capability + HP8904A Option 001 question
Radu and all,
?
I did come across the “microprecision” website but have not contacted them.? From past experience I have had little luck dealing with these sorts of business because they want for? you to send your unit in for repair ($$$).? I may try but have little hope.
?
I am also aware that that these products were marketed under the “National” brand but have never seen any documentation relating to this name also from searching.?
?
The VP-7635x unit is a close match but has a few added features as seen on the front panel.? But, again, searches for any service information brought up nothing although there was found a specification sheet for this model.? I did find an operating manual for the 7637 but it is a totally different unit.
?
Greg
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Boot Diskette HP1650/1651
All,
I am in dire need of a boot diskette for an HP 1650/1651 Logic Analyzer (Rev. 1.00) which I have restored. I have (so far) been unsuccessful in finding one. Should anyone have one to spare or know where one may be found, please drop me an email off the list. Many thanks in advance.
All the best,
Bill
|
Re: HP Masked Microcontroller Question
Thanks
Yes, I see what you mean.? I too understood that mask programming the main counter processor was expensive and HP likely purchased a lifetime supply of the 1820-2131 parts.? There is, however, some communication data between the GPIB processor and the main counter processor,?? HP must have thought ahead during their original design to allow the facility to communication with another peripheral such as the GPIB microcontroller.
Thanks
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Re: HP-8753E Reading HPGL Files
I am now editing those files inside of the 7470 emulator. I have also been able query the VNA at Address 16 for them using this toolkit. Looks like I can choose from a great many formats besides .bmp to save these files. In the past, I had always used the emulator to seek plots directly from the machine. I never knew it could convert these files into various formats.?
Rich?
On Sunday, February 27, 2022, 04:15:46 PM EST, nj902 <wb0emu@...> wrote:
John's 7470 program will render an HPGL file which you can capture as a .BMP file and then tweak in your computer such as to add a box border.
|
David C. Partridge
Dave McGuire
Jinxie
Attilio
Bill Weinel
