LM399AH sources

[bdunham7]

Shows the price of $26.31 if I just click on the link. Says "Not in stock, but orderable" so I am not sure what happens if one orders it.

At that price you can be pretty sure they aren't doing a 1kH burn in and rigorous tempco selection. Perhaps they have a deal with Analog Devices where there is some additional selection and custom marking, but that would be about it.  Still, compared to $17 for the LM399AH from Mouser, it might be the right deal for someone repairing a 34401A or something like that.

[dietert1]

The LM399AH i bought from S. Bruder (the german ebay link i posted above) show zener voltages within +/- 15 mV. So i think some of the statements made above are a bit fallen out of time. Those parts marked e4 have little to do with the parts you may find in 30 year old HP gear. One possible explanation i have is that fabs are performing much, much better nowadays, especially on simple parts like that. And if AD sell a simple part like that for several $, they can afford strict selection. Otherwise the price would be 50 cents and they would have to compete with no-name products.

Regards, Dieter

[mawyatt]

The 1st LM399 we got off eBay a couple years ago, was all over the place and likely not new although didn't have any visible solder on leads. When Mouser or DigiKey (can't remember) showed some stock we ordered a couple, later things dried up and no stock available. Then Mouser showed some stock ~6 months ago we ordered another.

Agree, I'm sure the LM399 of today are not like the old ones used by HP when National made them. Todays processes and equipment are so much better, suspect the yields are high and variation low. They may even be a different design and/or layout

Best,

[GigaJoe]

there is no such thing as cloned or knockoff 399 on ebay.  al of them 399.
bit the problem are conditions\state where have they been, and what stress they got.
most of them are de-monted parts with legs was reconstructed ,   that process of harsh re-soldering and reconstructing potentially caused some permanent damage, and side effect of non stability.

from approx 40 pcs  from ebay, the cheapest one .... after 6 month approx 70% still changing , after a year approx 45% - changing, after 3 years around 30%- changing ,   that include change output if  power on\off,  or sudden jump.

so run probability \ price of purchase retail VS used for long term stability.

[DavidKo]

It is hard to say who all produced them. But in our country it was Tesla (now part of ON Semi). I expect that there were more producers around the world and maybe still there are, than it is only about correct package.
http://www.teslakatalog.cz/MAB399.html

[iMo]

Sure, there are clones on the ebay available - the most popular item is the MAB399 (<5ppm/K) and rarely the MAC199A (<0.5ppm/K). Both are usually around 7.25V.
I got a batch of both in past, what is left after an initial measurement and ~1500h burn-in is 2x MAC199A.
Those were produced by TESLA (the former Czechoslovakian electronics/semi giant) in early 90ties, afaik. The die shot could be seen on the Noopy's page.

..
Agree, I'm sure the LM399 of today are not like the old ones used by HP when National made them. Todays processes and equipment are so much better, suspect the yields are high and variation low. They may even be a different design and/or layout

The experts here usually are looking for those old National ones -  those with 6.9V. The new ones you get from ADI (made by LT) are around 7.05V. People say the 6.9V ones have better stability and noise..

[IanJ]

The experts here usually are looking for those old National ones -  those with 6.9V. The new ones you get from ADI (made by LT) are around 7.05V. People say the 6.9V ones have better stability and noise..

I've bought hundreds via Digikey, and sometimes Analog Devices direct in the past say 3 years and have them vary from 6.9V thro' 7.05V.
Definitely see them vary in batches, and definitely the latest few batches have been at the higher end.

PS. Good to see that Digikey have 1788 in stock (LM399AH#PBF)......for a while there I was buying up all stocks available!

Ian.

[deepfryed]

I've bought hundreds via Digikey, and sometimes Analog Devices direct in the past say 3 years and have them vary from 6.9V thro' 7.05V.
Definitely see them vary in batches, and definitely the latest few batches have been at the higher end.

PS. Good to see that Digikey have 1788 in stock (LM399AH#PBF)......for a while there I was buying up all stocks available!

Ian.

I saw this on fleabay during my lunch break browsing, if you're interested in a risky bargain Ian

https://www.ebay.com.au/itm/304814679682

[GigaJoe]

mmm ... my guess ,  it reclaimed  \ used one  , the legs restored \ extended , they are  usually non even smooth if look under microscope, it 100% lm399 , a s there no fake one, plastic caps are new print, and cover usually not sit well.   on the picture mimic of old style national , but no side "Philippines batch # "
so it $5 per 1 in a volume,   as usually was such price on ebay per 1 ,  in old days ...

puzzle for me "MTR" meaning 

[dietert1]

You can find very strange offers there, e.g. https://www.ebay.de/itm/185842488871

I bought some on ebay marked "e4" and they are flawless. Very low tolerances and no popcorn noise. Made two arrays, one with 5x and a 14 V reference with 5x pairs. That one has a similar noise level as an ADR1399 except at twice the voltage.

Regards, Dieter

[deepfryed]

You can find very strange offers there, e.g. https://www.ebay.de/itm/185842488871

Wow, 115GBP for 2 LM399s feels like a ripoff. Unless I'm missing something obvious.