[volt-nuts] cadmium solder alloy for low thermal emf?

[David]

I do not imagine cadmium bearing solder being easy to acquire.  The
Wikipedia entry for solder says Pb90Sn10 can be used as a replacement
for Cd70Sn30 in low thermal EMF applications:

http://en.wikipedia.org/wiki/Solder

On Thu, 30 May 2013 04:00:19 +0200, Volker Esper <ailer2 at t-online.de>
wrote:

>
>By the way: does anyone know, if Agilent uses special solder alloy? I've 
>heard that a cadmium containing solder is used to get extremely low 
>thermoelectric voltages (or voltage differences).
>
>Is that right? If so, which alloy has to be used?
>
>Thanks
>
>Volker
>
>
>Am 30.05.2013 03:29, schrieb Volker Esper:
>>
>> Thank you for your suggestions.
>>
>> Yes, I tried to identify the connection that is faulty. Though I 
>> mistrusted all mechanical contacts (relays and front/rear switch), my 
>> greatest fear was, that one of the PLCCs would be defective...
>>
>> I opened the case and shortened all the closed contacts with an 
>> extremly low ohms short and the display changed significantly when 
>> coming to K101. Today I screwed up my courage and soldered a short 
>> wire across the contacts of this high voltage relay. It's been running 
>> for 12h now, without any wrong value.
>>
>> So I've got to get one of those relays - Agilent says "orderable" at 
>> about 40 Euro. That's quite fair, I think.
>>
>> Thanks so far
>>
>> Volker
>>
>>
>> Am 21.05.2013 17:39, schrieb Don at True-Cal:
>>> Volker,
>>>
>>> I agree with the assessment that Frank gave you, that one or several 
>>> high
>>> resistance connections between the terminals you are using and the
>>> connection to the main circuit board are at fault. This path would 
>>> include
>>> the front/back switch itself and any low EMF slip-on connectors between
>>> front/back terminals and switch as well as from switch to main board. 4W
>>> measurements can correct for this increasing and varying path 
>>> resistance but
>>> 2W measurements can't. I have seen this behavior in the 34401A and 
>>> even the
>>> 3458A as well. It's an easy fix. You can probably find the offending
>>> connection by wiggling each while watching the 2W reading with a 
>>> short on
>>> the terminals. If you see the problem on both front and rear 
>>> terminals, the
>>> fault is between the switch and main board. If only on front OR rear, 
>>> the
>>> fault is between that set of terminals and the switch. You will want to
>>> clean ALL connectors on both Input and Sense while you are inside.
>>>
>>> Hope this helps...
>>> Don @ True-Cal
>>>
>>>
>>> -----Original Message-----
>>> From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
>>> Behalf Of Frank Stellmach
>>> Sent: Tuesday, May 21, 2013 12:53 AM
>>> To: volt-nuts at febo.com
>>> Subject: [volt-nuts] Volt Nuts Rookie
>>>
>>> Hello Volker,
>>>
>>> welcome here.
>>>
>>> Currently, my 34401A shows a similar behaviour, on the rear 
>>> connectors only.
>>>
>>> 2W Ohm there drifts up and down, several 10 digits in 6 digit mode, 
>>> whereas
>>> the measurement is stable on the front connectors.
>>> 4W Ohm is stable even on rear connectors.
>>>
>>> Obviously, the front/rear switch is oxydized, or otherwise faulty.
>>>
>>> Please, check the measurement on the rear connectors also.
>>>
>>> Regards Frank
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>>
>>
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>
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