Electronics > Metrology

Low thermal EMF binding posts - a quality warning.

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Alex Nikitin:
I've used Pomona 3770 gold plated Tellurium Copper posts with good results for a while, however recently I've ordered a somewhat cheaper "Mueller" posts from Digikey, and found these to be a Chinese copy of Pomona ones, of inferior quality (cracks in the plastic, not as accurate shape) and - most important difference - Pomona posts are gold plated over copper directly, but Mueller ones have a Nickel layer as well (and still the gold layer peels off easily). Pomona posts cost only about 30% more.

Pomona 3770-0/2 - Digikey p/n 501-1612-ND, 501-1699-ND

Mueller BU-P3770-0/2 - Digikey p/n 314-1200-ND, 314-1196-ND

Cheers

Alex

d-smes:
Did you call Digi-Key about this?   They should have traceability of the parts they stock to the manufacturer and I bet they would like to know of the quality difference.   Maybe it's Mueller that decided to outsource the part instead of manufacture them...

chickenHeadKnob:
This is a very timely warning for me as I was just about to order the mueller posts. The plating layers should not come off, that is an indication there was a contaminant on the surface. Is the base metal on the mueller really copper? I would think one way to cheap out is to use brass  and simply claim copper which what I suspect most of the ebay sellers do as they think no one will check.

KE5FX:
Tellurium, huh?  I don't want to be around when they test those things for thermal EMF...

Alex Nikitin:

--- Quote from: chickenHeadKnob on August 17, 2016, 12:24:52 am ---This is a very timely warning for me as I was just about to order the mueller posts. The plating layers should not come off, that is an indication there was a contaminant on the surface. Is the base metal on the mueller really copper? I would think one way to cheap out is to use brass  and simply claim copper which what I suspect most of the ebay sellers do as they think no one will check.

--- End quote ---

No, the main body on Mueller posts appears to be copper, I've checked by cutting a bit off.

Cheers

Alex

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