Electronics > Metrology

Reversing switch

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zlymex:

--- Quote from: quarks on April 03, 2016, 01:55:32 pm ---Hello zlymex,

about Tellurium, as discussed with and confirmed by robrenz, CuTe is only used because it is much easier to work with lathe/milling tools. The emf properties should be worse then pure copper. But because there is only very little Te in CuTe, it seems to be there is almost no difference. All you have to avoid/take care of is oxidation. Therefore I prefer gold plating (but without Nickel layer underneath).

About the Fluke 7002 (4mm banana), they are the way to go, if you cannot use/connect the much better spade lug cables. I.e. on Fluke 5450A front connector is unfortunately 4mm banana only, which I do not like at all. Same is true for my R6581 an my 6.5 digit meters. Because of that, I have made several adapters, so I am able to use spade lugs.

Bye
quarks

--- End quote ---
It just because every nano-volt counts in a nano-voltmeter, you cannot choose materials other than pure copper no matter how hard they made. I had several dozens of pure copper binding posts custom made for this reason. I hate my 5450A and R6581 too. I'm going to take down/sell then.

quarks:

--- Quote from: zlymex on April 03, 2016, 03:53:20 pm ---I hate my 5450A and R6581 too. I'm going to take down/sell then.

--- End quote ---

if you really want to sell your R6581, please send me a PM with details, I am interseted to buy it

manganin:

--- Quote from: zlymex on April 01, 2016, 10:54:19 am ---But it does affect the properties doesn't it? The requirements for nano-meter is very strict. Take 34420A for example, the input connectors 'are almost pure copper (pp.271 manual), and certainly they are not gold-flashed. In the case of 3458A, they did say the terminal material is Gold-plated Tellurium Copper. Also, I just found out that they use pure copper terminals in their EM manometers

--- End quote ---

When we talk about machined parts, "copper" is hardly ever just copper. The electrolyte copper is a good material for punching, but very slow and difficult to machine. And threaded parts like binding posts would wear out quite fast.

According to my experience, protecting the connections from air currents (and everything else causing thermal gradients) is the most important thing. The copper alloy used and the possible gold plating come far behind.

lowimpedance:
 Hunting around for other switches I did find another one from the same manufacturer, so I could see exactly how it was put together (which has made it easier to reassemble all the bits correctly). Okay some pics side by side and re assembly complete, all bar the timber case.

lowimpedance:

--- Quote from: manganin on April 04, 2016, 11:38:56 am ---
--- Quote from: zlymex on April 01, 2016, 10:54:19 am ---But it does affect the properties doesn't it? The requirements for nano-meter is very strict. Take 34420A for example, the input connectors 'are almost pure copper (pp.271 manual), and certainly they are not gold-flashed. In the case of 3458A, they did say the terminal material is Gold-plated Tellurium Copper. Also, I just found out that they use pure copper terminals in their EM manometers

--- End quote ---

When we talk about machined parts, "copper" is hardly ever just copper. The electrolyte copper is a good material for punching, but very slow and difficult to machine. And threaded parts like binding posts would wear out quite fast.

According to my experience, protecting the connections from air currents (and everything else causing thermal gradients) is the most important thing. The copper alloy used and the possible gold plating come far behind.

--- End quote ---
I had to tweak the copper rotor brushes to make better contact on the stator and I found them to be quite soft and easliy 'manipulated'. here is a pic. of the rotor looking at the contact brush arrangement.

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