On Thu, Sep 1, 2022 at 12:17 PM, Mikek wrote:

I have two meters both older I know because of the AC plug.

?HP 3400A # 806-08346

HP 400E # 0949A11285

Looking at your numbers, as well as those of my older HP instruments, it's clear that HP did not start inserting the central letter (country) code right away. It appears that the new scheme that started in 1960 was yww-sssss. It looks like the central country code letter was introduced sometime in '68 or '69, and this may have happened at the same time HP added the leading zero, knowing that 1970 would require it.

It's important to understand that the date, year and week, denotes the date the (new or revised) design was finalized. It's not the build date. It also seems clear that the sequential serial number restarted at 00101 each time the serial prefix (date code) changed. It should also be noted that the serial prefix need not be unique to a particular HP model; it's conceivable that two different design teams could finalize on the same week. As HPs catalog grew, this must have happened often.

There's one (maybe more) exception to this: On HP pocket calculators, the date code IS the year and week of manufacture.

So the design of your 3400A was finalized in the 6th week of 1968, and likewise your 400E was based on the design of week 49 of 1969. If you're looking for a manual for your instrument, it's important to get one that covers your serial prefix. Manuals will often have backdating info as well as update sheets for later instruments. You can look at the serial prefixes for this instrument and bracket the date when yours must have been made.

One of the important things to understand is how many design revisions some of HPs products got. This was especially true of popular instruments which had long production lifetimes like the 200CD, 3400A, and all the various versions of the 400.

Trivia: Serial numbers of the form “09mmXnnnnn” can also appear as “9mm-nnnnn.” Such instruments would have been made in (late, usually) 1969, when the change in format was underway. I suspect this was a practical matter: serial number tags would have been ordered in quantity and in advance of production. Production management, if several hundred of the old serial tags were in stock, would lean towards using up the old ones before bearing the expense of ordering new ones.?

On Thu, Sep 1, 2022 at 10:17 AM Mikek <amdx@...> wrote:

I have two meters both older I know because of the AC plug.

?HP 3400A # 806-08346

HP 400E # 0949A11285

??? Thanks, Mikek

PS, I knew I saw a thread about this, I checked several groups I frequent and couldn't find it.
?
????????????

--

Jeremy Nichols
6.

I have two meters both older I know because of the AC plug.

?HP 3400A # 806-08346

HP 400E # 0949A11285

??? Thanks, Mikek

PS, I knew I saw a thread about this, I checked several groups I frequent and couldn't find it.
?
????????????

Hi All -

Back about five years ago, someone who'd worked for HP posted an explanation of the post-1960 serial numbering system, which I then re-posted with my interpretation of it on another forum. Here is a copy of my forum post - the original text is at the start, and my understanding of it follows.

"Copied and pasted from a post to the HPAK mailing list explaining the serial numbering system; the original author worked for HP:

Having worked as a Production Line Engineer, Production Line Manager and Product Support Manager(Americas) for one HP Division, please let me clarify the process for Engineering Changes and how that affects Serial Prefixes.

1. The Basic Identity of an Instrument is the Model No. (e.g. HP 8510A,HP8510B,HP8510C). These Models are all independent of each other and each of the three examples would start with a Serial No.(Suffix) of 00101

2. The most Major Engineering Changes to an Instrument (e.g. Addition of a bunch of New Features or Upgrades) could be implemented into a New Model No. (e.g. change from "A" model to "B" model). In the case of changing to a New Model No. the Serial No.(Suffix) will start again at 00101.

Short of a New Model No., all other changes would be handled through a "Production Change Order".

3. A Production Change Order may or may not trigger a New Serial Prefix. Typically, for instance, the change of a single component value would not cause a Serial Prefix change. I believe (but I'm not 100% on this), that would be decided by Production Engineer in conjunction with Product Support folks, who are responsible for Service Manuals. Major Engineering Changes would always trigger a New Prefix.

4. Instrument Manufacturing is done in Batches, called Production Runs. The Size of each Run is determined by Sales Volume. More Sales, Larger Runs.

5. A New Serial Prefix would be implemented for the Start of a New Production Run. Before issuing Work Orders for a New Production Run, I believe a review of Engineering Change Level would be done and the decision to introduce a New Prefix would be made or had already been made. That could be due to one Major change or sometimes a roll-up of a bunch of Minor ones.

Keep in mind none of this is instantaneous, 'cos of lead times for (new)material to be provisioned.

6. In an Emergency (quite rare), it has been known for a Production Change to be implemented immediately, maybe 'cos of a Safety concern(I did it only once) or some major Defect being discovered.

7. I think by now it has been well established that the Serial Prefix first two digits are the number of Years since 1960 and the last two are the week number of the last Production change included in the Instrument.

Sorry for being a bit Verbose, but that's how it works.

Paraphrasing my understanding of the above:

1: The model number and its letter suffix identifies the instrument type. Each is considered to be independent of the others for serial numbering purposes, and starts with a 00101 serial number suffix.

2: An expansion of (1) reiterating that the serial number resets with a new letter revision to an instrument when major changes are made. If it is only a rev change then the serial number will continue to increment sequentially from the last instrument made under the previous engineering rev.

3: Minor changes would not trigger a prefix update; more major ones (but those that were not enough to trigger a new model suffix revision) would trigger a prefix update.

4: When a design is released, they build a bunch at a time.

5: This one hung me up for a bit until I thought it through a bit more and paid attention to the wording. A new serial prefix would be implemented at the start of a new production run (note that it's 'would be', not 'will be' or 'is' - it only changes if the design is revised) Prior to the new run, they'd look everything over, and determine if a new prefix was needed; if it was not then the new run would get the old (but current to the design, as it's essentially unchanged) prefix.

To summarize my understanding of what 2-5 mean, for example, if the last unit of the run of the mythical HP 0000A Whatsis (introduced in the 32nd week of 1972) serial number 1232A00250 is finished and the design undergoes a major change to become an HP 0000B Whatsis in the second week of January, 1975, then the first new HP 0000B off the line will be serial number 1502A00101 (new prefix, reset serial). If, instead, the new iteration of the HP 0000A comes off the assembly line with a lesser engineering change (not enough to warrant it becoming a 'B' model), then the first unit in the new run will have a serial number of 1502A00251 (new prefix, incremented serial). If it's just a new run with no real changes, then the first off the line in January of 1975 would be serial number 1232A00251 (old prefix, incremented serial).

6 & 7: self explanatory.

I left the OP's name off because it was posted to the mailing list; if anyone wants to dig it was posted on 10/05/17."

-Pat

> ------ Original Message ------
> From: jn6wfo@...
> To: [email protected]
> Sent: Thursday, September 1, 2022 10:32 AM
> Subject: Re: [HP-Agilent-Keysight-equipment] How do you decipher HP serial numbers for date.

Actually, Matt’s serial number ID (mmmmXnnnnn where X is the country of manufacture) applies to designs (redesigns) finalized in or after 1970.

A=America (USA), G=Germany, J=Japan, U=United Kingdom, etc.

For 1960-1969, the serial number is of the form nnn-mmmm where the first part is the date code and the second part the series number. The first digit in the date code is added to 1960 to give the year. The second two digits are often said to be a week number but I’ve seen numbers higher than 52 so I’m unsure. For instruments with small unit runs, the serial number block is sometimes shared with other instruments.

For instruments before 1960, there’s a simple serial number that has no date significance. Numbers range from 1 to 5 digits; comparing the various versions of the manuals and catalogs, if you can find them, can give a rough idea of the date.

On Thu, Sep 1, 2022 at 5:52 AM Matt Huszagh <huszaghmatt@...> wrote:

The serial number consists of a 4-digit date code followed by a letter indicating the country of manufacture, followed by a sequence of digits that uniquely identifies the instrument.

In the 4-digit date code, the first two digits are the number of years since 1960 and the last two digits are the number of weeks into the year. This date code represents the date of design, not manufacture. It’s a common misconception that this means build date. It doesn’t.

For the country code, off memory, A is USA, J is Japan, M Malaysia. Probably others too. I think this indicates location of manufacture rather than design, but I could be wrong on that.

I think the 5-digit suffix is sequentially assigned based on build date, but I don’t know.

So, to answer your question you can’t really know when your instrument was built other than it was sometime after the date code. Previously, I expect HP would have been able to provide this information if you called in, but I doubt keysight would (or probably even could) tell you that anymore. But you could try.

FYI this question has been posed and answered a number of times before. A search on the HP-Agilent-Keysight group would yield the same info. The serial number format is also usually described at the beginning of instrument manuals.

Matt

--

Jeremy Nichols
6.

The serial number consists of a 4-digit date code followed by a letter indicating the country of manufacture, followed by a sequence of digits that uniquely identifies the instrument.

In the 4-digit date code, the first two digits are the number of years since 1960 and the last two digits are the number of weeks into the year. This date code represents the date of design, not manufacture. It’s a common misconception that this means build date. It doesn’t.

For the country code, off memory, A is USA, J is Japan, M Malaysia. Probably others too. I think this indicates location of manufacture rather than design, but I could be wrong on that.

I think the 5-digit suffix is sequentially assigned based on build date, but I don’t know.

So, to answer your?question you can’t really know when your instrument was built other than it was sometime after the date code. Previously, I expect HP would have been able to provide this information if you called in, but I doubt keysight would (or probably even could) tell you that anymore. But you could try.

FYI this question has been posed and answered a number of times before. A search on the HP-Agilent-Keysight group would yield the same info. The serial number format is also usually described at the beginning of instrument manuals.

Matt