Unused HP432A find...

[G0HZU_JMR]

I found the equivalent of a 'barn find' HP432A power meter recently so I wondered if anyone would like to see it. This old power meter was dry stored from new and appears unused. It still has all the leads and cables and paperwork and the user manual sealed from new. The seller opened the meter packaging to test the HP432A to see if it powered up but it looks absolutely brand new as if it's been in a time warp. The front panel is so clean and shiny I don't want to touch it. It looks like this meter was purchased and stored and never used. The sensor cable is still sealed so I think this is a clue it was never used. It still has all the original factory HP tamper seals on it. The picture below doesn't do it justice.

https://vgy.me/XQmTpr.jpg

I have another HP432A which I would describe as in immaculate condition and the best I've seen in a long time but this one in the image below looks like it is a few days old rather than several decades old. It looks like it has spent the whole time in a box in a storeroom. If I touched the glass on the meter and left a fingerprint I'd never get it as clean again. It really does look like it has just been unpacked as a new purchase

The (new unused) HP478A thermistor in the image is from a separate purchase and I'm hoping the seller of this meter can search and find the delivery box for the HP478A sensor that would have been ordered at the same time.

[mhennessy]

Wow!

Time to build a nice wooden display case with a glass front. What a display piece! And not to onerous to treat in that way, unlike some bits of gear.

Was it terribly expensive?

[Radio Wrangler]

Have a look at the serial number and it'll tell you what week it was made and whether in the US or UK.

Nice find. Mine is the old line standard one and all the transistors have dabs of coloured paint to make the different types obvious.

Remember, 10mW max into that sensor!

The NPL folk were up visiting for some discussions on noise source calibration in about 2000 and I gave them a tour round the plant and they spotted the 432 line in the distance and there were unanimous appeals from them to never stop producing the old 432 and to never remove the mount resistance switch!

David

[MrBungle]

That's a rather nice specimen. Everything in this form factor I've had from HP has been through the wars. I inherited a semi working one with power sensor from my father but the power sensor is somewhat knackered. Turns out they are rather expensive if you want one that actually works. Also easy to blow up so there are more power meters left than sensors!

I would pay a lot of money (£250+) for a 427A in that condition.

[G0HZU_JMR]

Thanks for the replies

It wasn't that expensive at about £150 considering it came with an unused sensor cable. Apparently these cables are quite rare.

I think the manuf date is 1990 in the USA but the formal HP cal sticker is dated 1992. Not sure if that means it may have been sent for cal at least once in its lifetime. Or maybe it didn't get sold straight away when it was new. There is a date on the manual but this is for the manual revision and this is 1988.

I bought my other HP432A some time ago and imported it from the USA. I think it was made in 1986. It was just $50 and is in very nice condition as seen in the link below.

https://vgy.me/eZHel4.jpg

But the 'new' one is really as new. Even the gold coloured contacts in the mount connector look sparkly fresh and clean and shiny like they are new and untouched like brand new jewellery. I'm going to try comparing the results between the meters when doing the DC substitution method. In theory the results should be the same (for a common HP478A sensor) because the external DMM does all the work.

[Radio Wrangler]

For 1990 in the USA, the serial prefix will be 30xxA..... where xx digits are the week number.

They're just superb instruments and the RF power measurement is a true DC substitution and is pretty accurate. For standards lab use, short of buying a NIST typeIV meter, a 432 with a pair of 6 digit DVMs has long been a standard approach.

David

[G0HZU_JMR]

OK thanks but I'm still a bit confused how the HP dating system works... I think my first attempt at dating this meter is wrong because I misunderstood the system. I did search on the internet and the first two digits set the number of years post 1960. So I can see why 30 would be 1990 as 1960 + 30 = 1990.

But if the manufacturing date for my meter works like that then my meter was made in 1978 because my prefix is 1848A3xxxx. This doesn't stack up with the paperwork. My other meter is also 1848A but it is 1848A2xxxx.

I had a look online and could find quite a few meters with the 1848A prefix with quite a spread in serial number. eg a spread of 12000.

Some online guides give the second pair of numbers as the week code. But others argue that it's not a week code but a batch code. But if these guides are correct then HP made a batch of over 12000 meters (possibly in just one week in 1978)... but that doesn't seem realistic.

My attempt at making sense of this is that the 1848A prefix possibly relates to the initial release date for a drawing set for meters built to that drawing set. The date for making the very first meters (to this drawing set) sets the prefix and I wonder if 18 = 1978 and 48 = ID code that corresponds to the HP432A (for that year) and A = made in USA.

Then there is a 5 digit serial number and obviously the bigger the number the newer the meter is and HP can date the meter by the serial number. So if you gave HP/Keysight a complete serial number based on 1848Axxxxx they would know it is a HP432A made to the 1978 drawing set and they could get the manufacturing date from a database from the remaining 5 xxxxx digits of the serial number.

But all of the above is just a guess and most likely wrong