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Date
Re: E5052A Power On Test (3.3V Bus Supply)

 

开云体育

Isn’t one solution to side modes using multiple (fiber) loops of different lengths, such that fewer frequencies fit?

(Borrowed thinking in terms of laser resonators and etalons where sometimes specific choices are made that permit only a single mode within the gain bandwidth of the amplifying media)
Re: HP 3403C True RMS Voltmeter display fault

 

开云体育

The OSCON type capacitors aren’t available in higher voltage ratings.

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> on behalf of Dave Daniel via groups.io <kc0wjn@...>
Sent: Tuesday, March 4, 2025 11:30:05 AM
To: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io>
Subject: Re: [HP-Agilent-Keysight-equipment] HP 3403C True RMS Voltmeter display fault
?
I'll add that since, in general, modern caps are smaller than vintage caps, make sure the the voltage rating of the new cap provides sufficient margin over the voltage rail. For instance, Tektronix often used caps rated for +15v on +12v rails. In all the cases where I have recapped equipment, a modern +25v cap was smaller in physical size than the original +15v caps.

DaveD
KC0WJN


On Tue, Mar 4, 2025 at 12:14 ed breya via <eb=telight.com@groups.io> wrote:
Arnaud, you can replace Ta caps with alternatives in most applications, so there's no need to spend too much for an original type. Usually ones that burn out are in supply bypassing spots, which are not critical. The main issue then is space available for new parts, since the common fix is to go with a much larger capacitance (and physical size) aluminum electrolytic type to get ESR comparable to the Ta ones. I'd say put in an Al cap of at least 2-10 times as much C as the original Ta, with enough V rating for the supply voltage. Or, use the biggest C that can physically fit into the space available. You can look at various brands and families of caps to choose the lowest ESR you can find, but they won't be dramatically different.
?
Another option is to go with an OSCON organic dielectric type Al cap. These are built for low ESR and can beat Ta in this respect, so fitting is easier. The problem here is that (I think) OSCONs are only available in radial mount style (can with leads out the bottom), so trickier to fit in axial-lead spots. If axials are available, then no problem.
?
Remember this all only applies to supply bypassing spots. Sometimes Ta is needed for particularly low DC leakage and better stability like in timing circuits. Ones in these kinds of spots hardly ever fail because they're not stressed. Supply bypassing ones fail a lot, but value stability and leakage hardly matter here, so bigger Al types or OSCONs (which have the worst leakage) work just fine to get decent ESR.
?
Ed
?
?
Re: HP 3403C True RMS Voltmeter display fault

 

I'll add that since, in general, modern caps are smaller than vintage caps, make sure the the voltage rating of the new cap provides sufficient margin over the voltage rail. For instance, Tektronix often used caps rated for +15v on +12v rails. In all the cases where I have recapped equipment, a modern +25v cap was smaller in physical size than the original +15v caps.

DaveD
KC0WJN


On Tue, Mar 4, 2025 at 12:14 ed breya via <eb=telight.com@groups.io> wrote:
Arnaud, you can replace Ta caps with alternatives in most applications, so there's no need to spend too much for an original type. Usually ones that burn out are in supply bypassing spots, which are not critical. The main issue then is space available for new parts, since the common fix is to go with a much larger capacitance (and physical size) aluminum electrolytic type to get ESR comparable to the Ta ones. I'd say put in an Al cap of at least 2-10 times as much C as the original Ta, with enough V rating for the supply voltage. Or, use the biggest C that can physically fit into the space available. You can look at various brands and families of caps to choose the lowest ESR you can find, but they won't be dramatically different.
?
Another option is to go with an OSCON organic dielectric type Al cap. These are built for low ESR and can beat Ta in this respect, so fitting is easier. The problem here is that (I think) OSCONs are only available in radial mount style (can with leads out the bottom), so trickier to fit in axial-lead spots. If axials are available, then no problem.
?
Remember this all only applies to supply bypassing spots. Sometimes Ta is needed for particularly low DC leakage and better stability like in timing circuits. Ones in these kinds of spots hardly ever fail because they're not stressed. Supply bypassing ones fail a lot, but value stability and leakage hardly matter here, so bigger Al types or OSCONs (which have the worst leakage) work just fine to get decent ESR.
?
Ed
?
?
Re: HP 3403C True RMS Voltmeter display fault

 

Arnaud, you can replace Ta caps with alternatives in most applications, so there's no need to spend too much for an original type. Usually ones that burn out are in supply bypassing spots, which are not critical. The main issue then is space available for new parts, since the common fix is to go with a much larger capacitance (and physical size) aluminum electrolytic type to get ESR comparable to the Ta ones. I'd say put in an Al cap of at least 2-10 times as much C as the original Ta, with enough V rating for the supply voltage. Or, use the biggest C that can physically fit into the space available. You can look at various brands and families of caps to choose the lowest ESR you can find, but they won't be dramatically different.
?
Another option is to go with an OSCON organic dielectric type Al cap. These are built for low ESR and can beat Ta in this respect, so fitting is easier. The problem here is that (I think) OSCONs are only available in radial mount style (can with leads out the bottom), so trickier to fit in axial-lead spots. If axials are available, then no problem.
?
Remember this all only applies to supply bypassing spots. Sometimes Ta is needed for particularly low DC leakage and better stability like in timing circuits. Ones in these kinds of spots hardly ever fail because they're not stressed. Supply bypassing ones fail a lot, but value stability and leakage hardly matter here, so bigger Al types or OSCONs (which have the worst leakage) work just fine to get decent ESR.
?
Ed
?
?
Re: HP 54512B (pair) repair

 

Mike,
No worries, everything I'm doing is at my own risk and expense. I welcome any ideas - Razvan, Jim thanks to you too!
Radu


On Tue, Mar 4, 2025, 7:54 AM Michael Bafaro via <m.bafaro=comcast.net@groups.io> wrote:

Radu,

?

I am not sure what the chemical is that they are using.? You need to find out what it is from someone who is familiar with chemicals such as a chemical engineer.? I would guess that something like acetone may work but I’m just guessing.? Of course, you need to put a sheet of some kind under the arm to protect the rest of the instrument.? I assume no responsibility for this suggestion.

?

Mike

?

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> On Behalf Of Radu Bogdan Dicher via
Sent: Monday, March 3, 2025 3:17 PM
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair) repair

?

Thank you, Mike.?

?

In terms of removing the arm from the switch stub (see pics enclosed a few messages down), where HP decided to use this brown resin to glue them together (completely unnecessary, in my opinion - how about a cable tie or something easy to remove and replace?...), what would be some recommendations in handling this? Specifically, safely and non-destructively detaching the arm from the stub. The arm is marked: "SPREAD JAWS TO INSTALL AND REMOVE," but due to the resin, that was just about impossible upon my examination when doing this.?

  • Can anyone determine or have some educated?guess regarding what sort of glue or resin that'd be? I tried seeing if I could scrape it or shatter it off, to no avail. It's tough and very hardened in place. Much?harder than either of the two plastics it joins.?
  • Solvents? I'd be pretty weary using liquid chemicals over the main board, but maybe something is recommended and safe to use in a situation like this.?
  • What else would?work? I assume others may have had this problem?and came up with some good solutions.?

Thank you,

Radu.?

?

On Mon, Mar 3, 2025 at 8:32?AM Michael Bafaro via <m.bafaro=comcast.net@groups.io> wrote:

Radu,

?

I wish you luck finding a replacement for the line filter and switch.

?

Mike

?

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> On Behalf Of Radu Bogdan Dicher via
Sent: Monday, March 3, 2025 10:23 AM
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair) repair

?

Mike,

This is unrelated with the issues I'm having with the -12V rail. When disassembling/reassembling the scope, the EMI Filter?(more specifically, its built-in switch) and the HP arm/button broke apart. I can now either try to find replacements, or just replace?the EMI Filter with a unit having the switch accessible from the back of the scope (this type is relatively easy to find) and disable the actuation of the front button.?

Radu.?

?

On Mon, Mar 3, 2025 at 8:16?AM Michael Bafaro via <m.bafaro=comcast.net@groups.io> wrote:

Radu,

?

The pictures you sent appear to be the AC line filter (EMI) and the power switch and perhaps the line fuse.? If one of the supplies is off and the others are working, then the problem is somewhere else.?

?

The display is a standard magnetic deflected CRT.? I worked in that group years ago at Motorola.

?

Mike Bafaro

?

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> On Behalf Of Radu Bogdan Dicher via
Sent: Sunday, March 2, 2025 7:14 PM
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair) repair

?

Two steps forward, one step back (one and a half?).?

?

While other things have been progressing, the power switch stopped?working once I put?most of the?unit back together. I enclose some pictures, but it's a typical flip flop type where a pin prods and finds two different locations between the?two states ON/OFF. I guess I can either look for a replacement (does anyone have one?), or try to repair it. Repairing something like this hasn't been something?I've had a lot of luck with - if anyone has some good tips, I'll take them happily - and then there's also the way the longitudinal arm (actuating the pressing of?the button on the front panel all the way to the back) is supposed to be handled. It seems to be glued with some hardened resin or something similar. In retrospect, though the SM doesn't mention this, I think the arm should be detached before removing the rear panel and moving it around. It puts too much pressure?and torque on the switch to take this easily and not get damaged.?

?

Thank you for any pointers.?

Radu.?

?

On Sun, Mar 2, 2025 at 3:20?PM Radu Bogdan Dicher via <vondicher=gmail.com@groups.io> wrote:

Razvan,

Thank you very much, this is very helpful.?

I've managed to rig a load - I had a couple of 1ohm/10W Vishay RS10s (bulletproof, in my experience), and it looks like the -12V rail is MIA because of something going on in the PS. If I can confirm?this, this would be great news (as opposed to tracking some failed tantalum decoupler or something else on the main board....).?

Radu.?

?

On Sun, Mar 2, 2025 at 2:51?PM Razvan Popescu via <yo8ryr=gmx.net@groups.io> wrote:

Hi Radu,

I think the PSU in all 545xx series was made by Boschert Inc. and
someone already reverse engineered it. I attached the file.

I hope it helps.

Regards,
Razvan

On 02/03/2025 23:33, Radu Bogdan Dicher via wrote:
> Going back to my -12V rail issue, the SM advises loading the 5.20V rail
> with a 2ohm/25W resistor. The only way I can put something similar
> together with what I have at hand is using these dummy loads I am using
> when repairing audio amplifiers, which are a pair of 8ohm/100W non-
> inductive resistors. By paralleling?them I can load the 5.20V rail with
> a 4ohm resistor.
> What are some thoughts regarding whether this would be a suitable load
> for the PS? I think the PS just needs a low ohmic load of sufficient
> dissipation capacity and it should crank itself up to nominal, but maybe
> there's an aspect I'm overlooking.
> Thank you,
> Radu.
>
> On Sun, Mar 2, 2025 at 1:52?PM Radu Bogdan Dicher via <> > <vondicher=gmail.com@groups.io <mailto:gmail.com@groups.io>>
> wrote:
>
>? ? ?One of the two scopes is completely disassembled - head exploding
>? ? ?emoji - and I have the old battery desoldered after confirming?it's
>? ? ?fully depleted.
>
>? ? ?I enclose pics with what I'm using for replacement. I probably would
>? ? ?have been fine going with a 2032 type, but the 2430 I ended?up
>? ? ?fitting just right (maybe a bit snug), and the pins of the holder
>? ? ?actually match the PCB eyelets. So all is good.
>
>? ? ?I couldn't figure out what exactly was the original battery model,
>? ? ?as it's not legible even after removing the top tab, but its
>? ? ?diameter is a bit over 23mm.
>? ? ?I think this should work OK.
>
>? ? ?Back to the?actual troubleshooting now!
>? ? ?Radu.
>
>? ? ?On Fri, Feb 28, 2025 at 6:21?PM Roy J. Tellason, Sr. via
>? ? ?<> <roy=rtellason.com@groups.io
>? ? ?<mailto:rtellason.com@groups.io>> wrote:
>
>? ? ? ? ?On Thursday 27 February 2025 04:09:31 pm Radu Bogdan Dicher via
>? ? ? ? ? <> wrote:
>? ? ? ? ? > One other unfortunate effect of the spot-welding of the top
>? ? ? ? ?tab is that the
>? ? ? ? ? > battery code is not visible. I can probably destroy the
>? ? ? ? ?battery once out,
>? ? ? ? ? > and read the CRxyzt battery code, but would anyone have good
>? ? ? ? ?info offhand
>? ? ? ? ? > on it?
>
>? ? ? ? ?You might find bits of this useful:
>
>? ? ? ? ? <>? ? ? ? ?>
>
>? ? ? ? ?Scroll down to where they discuss coin and button cells:
>
>? ? ? ? ?"IEC designation numbers indicate the physical dimensions of the
>? ? ? ? ?cylindrical cell. Cells less than one centimeter in height are
>? ? ? ? ?assigned four-digit numbers, where the first two digits are the
>? ? ? ? ?diameter in millimeters, while the last two digits are the
>? ? ? ? ?height in tenths of millimeters. Taller cells are assigned five-
>? ? ? ? ?digit numbers, where the first two digits are the diameter in
>? ? ? ? ?millimeters, followed by the last three digits indicating the
>? ? ? ? ?height in tenths of millimeters."
>
>? ? ? ? ?So the size of the battery will give you the info that you need.
>
>? ? ? ? ?--
>? ? ? ? ?Member of the toughest, meanest, deadliest, most unrelenting -- and
>? ? ? ? ?ablest -- form of life in this section of space, ?a critter that can
>? ? ? ? ?be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet
>? ? ? ? ?Masters"
>? ? ? ? ?-
>? ? ? ? ?Information is more dangerous than cannon to a society ruled by
>? ? ? ? ?lies. --James
>? ? ? ? ?M Dakin
>
>
>
>
>
>


Re: HP 54512B (pair) repair

 

开云体育

Radu,

?

I am not sure what the chemical is that they are using.? You need to find out what it is from someone who is familiar with chemicals such as a chemical engineer.? I would guess that something like acetone may work but I’m just guessing.? Of course, you need to put a sheet of some kind under the arm to protect the rest of the instrument.? I assume no responsibility for this suggestion.

?

Mike

?

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> On Behalf Of Radu Bogdan Dicher via groups.io
Sent: Monday, March 3, 2025 3:17 PM
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair) repair

?

Thank you, Mike.?

?

In terms of removing the arm from the switch stub (see pics enclosed a few messages down), where HP decided to use this brown resin to glue them together (completely unnecessary, in my opinion - how about a cable tie or something easy to remove and replace?...), what would be some recommendations in handling this? Specifically, safely and non-destructively detaching the arm from the stub. The arm is marked: "SPREAD JAWS TO INSTALL AND REMOVE," but due to the resin, that was just about impossible upon my examination when doing this.?

  • Can anyone determine or have some educated?guess regarding what sort of glue or resin that'd be? I tried seeing if I could scrape it or shatter it off, to no avail. It's tough and very hardened in place. Much?harder than either of the two plastics it joins.?
  • Solvents? I'd be pretty weary using liquid chemicals over the main board, but maybe something is recommended and safe to use in a situation like this.?
  • What else would?work? I assume others may have had this problem?and came up with some good solutions.?

Thank you,

Radu.?

?

On Mon, Mar 3, 2025 at 8:32?AM Michael Bafaro via <m.bafaro=comcast.net@groups.io> wrote:

Radu,

?

I wish you luck finding a replacement for the line filter and switch.

?

Mike

?

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> On Behalf Of Radu Bogdan Dicher via
Sent: Monday, March 3, 2025 10:23 AM
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair) repair

?

Mike,

This is unrelated with the issues I'm having with the -12V rail. When disassembling/reassembling the scope, the EMI Filter?(more specifically, its built-in switch) and the HP arm/button broke apart. I can now either try to find replacements, or just replace?the EMI Filter with a unit having the switch accessible from the back of the scope (this type is relatively easy to find) and disable the actuation of the front button.?

Radu.?

?

On Mon, Mar 3, 2025 at 8:16?AM Michael Bafaro via <m.bafaro=comcast.net@groups.io> wrote:

Radu,

?

The pictures you sent appear to be the AC line filter (EMI) and the power switch and perhaps the line fuse.? If one of the supplies is off and the others are working, then the problem is somewhere else.?

?

The display is a standard magnetic deflected CRT.? I worked in that group years ago at Motorola.

?

Mike Bafaro

?

From: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> On Behalf Of Radu Bogdan Dicher via
Sent: Sunday, March 2, 2025 7:14 PM
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair) repair

?

Two steps forward, one step back (one and a half?).?

?

While other things have been progressing, the power switch stopped?working once I put?most of the?unit back together. I enclose some pictures, but it's a typical flip flop type where a pin prods and finds two different locations between the?two states ON/OFF. I guess I can either look for a replacement (does anyone have one?), or try to repair it. Repairing something like this hasn't been something?I've had a lot of luck with - if anyone has some good tips, I'll take them happily - and then there's also the way the longitudinal arm (actuating the pressing of?the button on the front panel all the way to the back) is supposed to be handled. It seems to be glued with some hardened resin or something similar. In retrospect, though the SM doesn't mention this, I think the arm should be detached before removing the rear panel and moving it around. It puts too much pressure?and torque on the switch to take this easily and not get damaged.?

?

Thank you for any pointers.?

Radu.?

?

On Sun, Mar 2, 2025 at 3:20?PM Radu Bogdan Dicher via <vondicher=gmail.com@groups.io> wrote:

Razvan,

Thank you very much, this is very helpful.?

I've managed to rig a load - I had a couple of 1ohm/10W Vishay RS10s (bulletproof, in my experience), and it looks like the -12V rail is MIA because of something going on in the PS. If I can confirm?this, this would be great news (as opposed to tracking some failed tantalum decoupler or something else on the main board....).?

Radu.?

?

On Sun, Mar 2, 2025 at 2:51?PM Razvan Popescu via <yo8ryr=gmx.net@groups.io> wrote:

Hi Radu,

I think the PSU in all 545xx series was made by Boschert Inc. and
someone already reverse engineered it. I attached the file.

I hope it helps.

Regards,
Razvan

On 02/03/2025 23:33, Radu Bogdan Dicher via wrote:
> Going back to my -12V rail issue, the SM advises loading the 5.20V rail
> with a 2ohm/25W resistor. The only way I can put something similar
> together with what I have at hand is using these dummy loads I am using
> when repairing audio amplifiers, which are a pair of 8ohm/100W non-
> inductive resistors. By paralleling?them I can load the 5.20V rail with
> a 4ohm resistor.
> What are some thoughts regarding whether this would be a suitable load
> for the PS? I think the PS just needs a low ohmic load of sufficient
> dissipation capacity and it should crank itself up to nominal, but maybe
> there's an aspect I'm overlooking.
> Thank you,
> Radu.
>
> On Sun, Mar 2, 2025 at 1:52?PM Radu Bogdan Dicher via <> > <vondicher=gmail.com@groups.io <mailto:gmail.com@groups.io>>
> wrote:
>
>? ? ?One of the two scopes is completely disassembled - head exploding
>? ? ?emoji - and I have the old battery desoldered after confirming?it's
>? ? ?fully depleted.
>
>? ? ?I enclose pics with what I'm using for replacement. I probably would
>? ? ?have been fine going with a 2032 type, but the 2430 I ended?up
>? ? ?fitting just right (maybe a bit snug), and the pins of the holder
>? ? ?actually match the PCB eyelets. So all is good.
>
>? ? ?I couldn't figure out what exactly was the original battery model,
>? ? ?as it's not legible even after removing the top tab, but its
>? ? ?diameter is a bit over 23mm.
>? ? ?I think this should work OK.
>
>? ? ?Back to the?actual troubleshooting now!
>? ? ?Radu.
>
>? ? ?On Fri, Feb 28, 2025 at 6:21?PM Roy J. Tellason, Sr. via
>? ? ?<> <roy=rtellason.com@groups.io
>? ? ?<mailto:rtellason.com@groups.io>> wrote:
>
>? ? ? ? ?On Thursday 27 February 2025 04:09:31 pm Radu Bogdan Dicher via
>? ? ? ? ? <> wrote:
>? ? ? ? ? > One other unfortunate effect of the spot-welding of the top
>? ? ? ? ?tab is that the
>? ? ? ? ? > battery code is not visible. I can probably destroy the
>? ? ? ? ?battery once out,
>? ? ? ? ? > and read the CRxyzt battery code, but would anyone have good
>? ? ? ? ?info offhand
>? ? ? ? ? > on it?
>
>? ? ? ? ?You might find bits of this useful:
>
>? ? ? ? ? <>? ? ? ? ?>
>
>? ? ? ? ?Scroll down to where they discuss coin and button cells:
>
>? ? ? ? ?"IEC designation numbers indicate the physical dimensions of the
>? ? ? ? ?cylindrical cell. Cells less than one centimeter in height are
>? ? ? ? ?assigned four-digit numbers, where the first two digits are the
>? ? ? ? ?diameter in millimeters, while the last two digits are the
>? ? ? ? ?height in tenths of millimeters. Taller cells are assigned five-
>? ? ? ? ?digit numbers, where the first two digits are the diameter in
>? ? ? ? ?millimeters, followed by the last three digits indicating the
>? ? ? ? ?height in tenths of millimeters."
>
>? ? ? ? ?So the size of the battery will give you the info that you need.
>
>? ? ? ? ?--
>? ? ? ? ?Member of the toughest, meanest, deadliest, most unrelenting -- and
>? ? ? ? ?ablest -- form of life in this section of space, ?a critter that can
>? ? ? ? ?be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet
>? ? ? ? ?Masters"
>? ? ? ? ?-
>? ? ? ? ?Information is more dangerous than cannon to a society ruled by
>? ? ? ? ?lies. --James
>? ? ? ? ?M Dakin
>
>
>
>
>
>


Re: 48-440 Hz AC power compatibility option (HP 8660B OPT 003) - acoustic noise (hum/buzz) from the unit?

 

Well I have run into the laminates?also.
But on a HP8640b it was the transformer and it finally let the smoke out. This happened some 20 years ago and on that generator I plumbed in a external linear supply. It lives in the basement and is a backup backup backup... So trying to find a replacement never made sense.
Paul
Re: 48-440 Hz AC power compatibility option (HP 8660B OPT 003) - acoustic noise (hum/buzz) from the unit?

 

Years back I had a problem in my 8660 where I had 60 Hz sidebands on the CW output that exceeded spec.? After extended troubleshooting and consultations with the (at the time) Yahoo group it came out that the problem was not electrical in the power supply itself but related to the transformer which was creating an external magnetic field which was inducing current into the instrument frame rear section which formed a pickup loop and this 60 Hz ground potential shift was getting into various electronics.? Mechanically breaking the loop temporarily would eliminate the output noise and I considered a mechanical solution involving a machined FR4 piece to replace a small aluminum section but eventually was able to find a replacement transformer which solved the problem.? It didn't eliminate the problem but attenuated the 60 Hz to where it was acceptable and within spec.

The new transformer was audibly quieter as well.? IIRC it was the 400 Hz capable one, as was the replacement.? I believe most of the instruments available at the time were military surplus.

I disassembled the old transformer with guidance from at least one person from old HP who was intimately involved with this generator and even posted photos but there was no obvious faults found such as an unsoldered or cracked copper sheet shield.

One conclusion was that it was entirely possible that some instruments left the factory out of spec due to issues in their transformers.

I still have the instrument and it still works but needs alignment and the low frequency plug-in needs repair at some point.? Much of the alignment can be done without extenders but some adjustments cannot be done without and that's kept me from working on it in favor of other projects.? Perhaps I can borrow a set from someone at some point.

Peter

On 3/3/2025 10:34 PM, David Feldman via groups.io wrote:
My AC mains 60 Hz (however, good question!)

Other than irritating (and not really all that bad, seeing as the cooling fan is about the same total dBa), it was more of a concern that it might be indicating something (else) wrong with the unit.

I could see running one of these at 400 Hz on an aircraft, but the aircraft probably couldn't get off the ground with this thing aboard.

Thanks for your description/info, much appreciated!

Dave
Re: HP 3403C True RMS Voltmeter display fault

 

Hey everyone,
?
I'll check whether or not the blob will melt. Both capacitors have this blob, although it is more pronunced on the dead one. Considering that we can now see inside the capacitor I think it's indeed solder. It was there when I got it, and the caps date code match the rest of the instrument.?
Is it wise to reuse the old one which is good, but looks justs as weird? I'll post a picture later when on lunch pause.
I have already mapped the original part numbers for the capacitors in the unit based on the manual, I need to check the actual reality of it. I'll post the sheet when I'm done. They're basically all still available new, albeit at a premium. Once again a costly order.
?
After that I'll adjust the voltage again, and try to calibrate it. I do not own a trustable RF source yet as my Marconi 2018A is in repair aswell (and part of the order), but I do own an Adret 104A DC voltage standard which is good enough for decent DC calibration.
It's probably been one or two decades since this thing had someone try to calibrate it. I'm worried about the converter internal state. Testing it, it's of course not accurate but it's not widdly far from it. I've tested it up to about 20MHz. DC is particularly close.
?
Cheers,
Arnaud.
Re: E5052A Power On Test (3.3V Bus Supply)

 

Thanks, Jim!
?
We have gone through all the usual suspects when choosing the phase noise kit for this round. There was also NoiseXT (is it former Aeroflex?)
Cross-correlation is a great advantage but you have to start with decent phase noise LOs if you want to keep the R&D cycle sensible.
I have no idea how people design long term high stability oscillators in one lifetime!
Leo
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On Sun, Mar 2, 2025 at 09:51 PM, Jim Ford wrote:

Watching this subject with interest.? Leo, you may want to check out OEWaves, Synergy Microwave, and Holzworth Instrumentation (now part of Maury Microwave) for ultralow PN sources and Rohde & Schwarz, OEWaves and Holzworth for measurement instruments.? Also, there are several source mfrs making sapphire resonant cavity oscillators.? You probably already know about these companies, but throwing the names out there just in case. Microchip (was Microsemi, was Symmetricomm, was Ball Efratom; correct me if I got that progression wrong) as well.
?
I bought one of your GPSDO models a few years ago; it's great!? Looking forward to getting one (or more) of your pulsers at some point.
?
I'm working on a synthesizer myself based on a long spool of optical fiber to get the ultralow phase noise.? The tradeoff is sidemodes, which are spurs in the microwave output.? I have an idea for a way to knock those down.? My goal is a low SWaP-C synth mainframe in a 3 rack unit box that can be expanded from 1 to 8 outputs DC to 18 GHz or so.? I just don't have the room for multiple 4 RU boxes (HPAK 8340, 8662, etc.)? Stay tuned!
?
Jim Ford
Laguna Hills, California, USA
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Re: E5052A Power On Test (3.3V Bus Supply)

 

Thank you Jeremy,
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I might pick one up to play with.
?
I have spoken to Jeremy Everard last year about shared low phase oscillators development and ended up sending him the actives I was using that they were going to test at the department.
He was using fully kitted out FSWP26 at the time but it was not perfect for low phase noise work.
To be honest far out noise between -170 and -180 is not a problem since cross-correlation gets it cleaned ?up within a minute or two.
It's the close in at 1Hz which takes forever to stabilise — I usually have to wait 30-40 minutes for it to reach -120dBc/Hz at 1Hz for 10MHz carrier.
Also 10-100Hz is a very problematic area where a lot of hash is holding cross-correlation stubbornly high for longer.
Leo
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On Sun, Mar 2, 2025 at 10:56 AM, jmr wrote:

The best thing about the E5052A is that it is very fast. What isn't so good is the qty of internal spurious terms, especially the one from the backlight at 60 kHz. I don't think it can compete with modern alternatives in terms of the noise floor it can achieve. The E5052B is going to be better I think. Hopefully the internal spurious are improved on the E5052B as well.
Re: HP 3403C True RMS Voltmeter display fault

 

开云体育

When the orange “tombstone” plastic encapsulated surface mount tantalum caps fail, they fail shorted.

Last year, while powering up a 9000/715, I saw one actually flame because I had the good fortune to have the case open. Fortunately, damage was minimal and i happened in have a partial real of an exact replacement.

I’ve had other tantalum capacitors fail, orange drop epoxy dipped, actually incandesce and shoot an glowing slug about 5 feet away onto the carpet.
Re: HP8510C TRL Calibration

 

Once calibration/correction constants have been computed externally on a computer, would it be possible to upload the computed correction constants to the 8510C so it can do calibrated measurements with this externally determined correction?
If so, how? This would allow correction schemes that the 8510C not originally allows.
?
Tom
Re: 48-440 Hz AC power compatibility option (HP 8660B OPT 003) - acoustic noise (hum/buzz) from the unit?

 

My AC mains 60 Hz (however, good question!)

Other than irritating (and not really all that bad, seeing as the cooling fan is about the same total dBa), it was more of a concern that it might be indicating something (else) wrong with the unit.

I could see running one of these at 400 Hz on an aircraft, but the aircraft probably couldn't get off the ground with this thing aboard.

Thanks for your description/info, much appreciated!

Dave
Re: 48-440 Hz AC power compatibility option (HP 8660B OPT 003) - acoustic noise (hum/buzz) from the unit?

 

Do you mean that the audible noise is there when operating on 400 Hz, or that it's there at 50 or 60 Hz now? You are right to suspect the core laminations buzzing. On transformers intentionally built to run well up to 400 Hz, the laminations are usually quite a bit thinner than for 50/60 Hz, so tend to be more pliable and can rattle against each other if anything is too loose. Usually the whole transformer would be vacuum impregnated with some kind of varnish or other goop that damps the motions at all frequencies, but after so many years it can deteriorate or get rusty, or the core mounting may loosen up. This all can happen in a regular 50/60 Hz unit too. Also, a regular unit can work at 400 Hz too, but the core loss goes up, so it would tend to run hotter, and you would want a little derating of thermal specs - usually no big deal.
?
You can look at the condition and try tightening or loosening it up first, then look to see if a particular area is emitting most of the power. If it's an E-I core, the corners can be quite tight due to the mounting screws, but the rest in between tends to bow and form gaps that allow motion. Sometimes it can be mostly caused by a gap around a single lamination that's just right to resonate and be irritating. If there's room enough, you can poke around between laminations with a razor blade and maybe find spots where it can jam in and greatly change the sound situation. If you ID any really bad ones, you can jam a paper or plastic shim in there.
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The noise is harmless to the machine, but you can get eddy currents that circulate in and around the chassis depending on the electro-mechanical character and condition of the core mounting scheme, so there can be some signal interference. I wouldn't worry too much about it in this old gear, unless it seriously affects the specs or is very irritating.
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Ed
48-440 Hz AC power compatibility option (HP 8660B OPT 003) - acoustic noise (hum/buzz) from the unit?

 

My HP 8660B (subject of the instability issue now resolved) includes option 003 which is compatibility with 48-440 Hz power sources.

The HP 8660B has a linear power supply (ca. 1970s, predates switchers), presumably to improve the ability of the unit to serve as ballast on a large ocean-going vessel, among it's other capabilities.)

Question is this - the machine emits an acoustic (audible) noise after being on for a few minutes. I didn't pay attention to this before, but realized that the noise may be associated with the wide-range AC mains frequency compatibility - I figured it was just plates in the power transformer rattling.

In my (now obsolete) work life (mostly in cable tv engineering), "ferroresonant" power transformers (used to adapt 60 Hz local mains power to the 60-90 Hz pseudo-sinewave power used in the cable tv hardline infrastructure to deliver power to inline amplifiers), the noise was similar.

Does this (acoustic) noise ring a bell with anyone? Should I be concerned? The machine doesn't appear to exhibit any operating problems related to this (and I doubt has anything to do with the now-mitigated PLL issue).

Thanks

Dave
Re: 8656B HPIB connector

 

Save money and defer the repair until such time as you have a need to use GPIB.

The connectors are reasonably easy to find around here but very costly to ship.

Peter
KB2VTL

On 3/3/2025 5:29 PM, Wayne Eckert via groups.io wrote:
Hi all, working on my 8656B sig gen, and managed to break the IDC Centronics connector , so the cable is no longer attached. Is there a suitable replacement available taht is not too ex[ensive. Have to replace teh mains socket as smoke came out, still waiting on that, and it cost over $86Aus? from RS on its own.I don't want to spend more than the device is worth to fix it, not that I am likely to use this port
Wayne
VK2WDE
Re: 8656B HPIB connector

 

Hi thanks for the reply, I think part of the connector may be missing, I have moved house a few times , with the back panel hanging of the unit? from when I was investigating the power socket issue. This is what led to the cable being pulled out of the connector. I will have a close look and see what I may be able to do when the power connector gets here.
Also my eyesight and steady hands are not what they used to be.
Do the documents indicate which colour wire is pin 1?
?I need to blow up the manuals more to be able to read them
Re: 8656B HPIB connector

 

You know, if it's not broken too badly, you can reattach the IDC into the ribbon cable manually by slowly and carefully jamming the leads against the forks in the connector. Put the connector in a vise or other secure holder, and align the ribbon cable carefully to be sure of the right pinning, with the forks in a fresh spot on the insulation. Then use a broad flat screwdriver tip or a piece of sheet stock to gradually push the lines into the forks. Start between the rows of forks, and run back and forth across from one edge of the cable to the other, each time pushing the insulation a bit deeper until punched through. Then push the areas farther out from centerline a little at a time until it's reasonably flat and thoroughly punched through all around. If the plastic cover is intact you can attach it and squeeze it tight, or epoxy it on if necessary.
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If it's messed up so much such that the forks can't be used, you can with some artful lead prepping just solder each one to its corresponding fork directly. This old-school stuff is big enough that a steady hand and decent vision can get the job done, and there aren't all that many lines - I think 20 or 24 max. Use a small iron, and pre-tin the lead ends and forks.
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Ed
8656B HPIB connector

 

Hi all, working on my 8656B sig gen, and managed to break the IDC Centronics connector , so the cable is no longer attached. Is there a suitable replacement available taht is not too ex[ensive. Have to replace teh mains socket as smoke came out, still waiting on that, and it cost over $86Aus? from RS on its own.I don't want to spend more than the device is worth to fix it, not that I am likely to use this port
?
Wayne
VK2WDE
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