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

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@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of Frank Stellmach Sent: Tuesday, May 21, 2013 12:53 AM To: volt-nuts@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 _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.

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@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@febo.com [mailto:volt-nuts-bounces@febo.com] On > Behalf Of Frank Stellmach > Sent: Tuesday, May 21, 2013 12:53 AM > To: volt-nuts@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 > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > >

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@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@febo.com [mailto:volt-nuts-bounces@febo.com] On >> Behalf Of Frank Stellmach >> Sent: Tuesday, May 21, 2013 12:53 AM >> To: volt-nuts@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 >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >

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@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@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@febo.com [mailto:volt-nuts-bounces@febo.com] On >>> Behalf Of Frank Stellmach >>> Sent: Tuesday, May 21, 2013 12:53 AM >>> To: volt-nuts@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 >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >>> >> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> > > >_______________________________________________ >volt-nuts mailing list -- volt-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >and follow the instructions there.

Hello >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@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 >> Within LT AN86 Cd60Sn40 is recommended for a limited temperature range of 0 to around 40 degrees. http://cds.linear.com/docs/en/application-note/an86f.pdf But: the thermal EMF is only zero against copper. Most precision integrated (hermetical) cirquits use Kovar. (39uV/K against copper) Relay contacts will be either copper berillium or another material. So in most cases a optimized solder for copper/copper connections will not be useful. On the other side Cd containing solders create very poisonous damps when being heated. With best regards Andreas

A few months ago I send Indium an email inquiring about low thermal EMF solders. A good choice is Sn10Pb90, or Indalloy 159. Andy Bardagjy bardagjy.com On Thu, May 30, 2013 at 5:05 AM, Andreas Jahn <Andreas_-_Jahn@t-online.de>wrote: > > Hello > > > 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<http://en.wikipedia.org/wiki/Solder> >> >> On Thu, 30 May 2013 04:00:19 +0200, Volker Esper <ailer2@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 >>> >>> > Within LT AN86 Cd60Sn40 is recommended for a limited temperature range of > 0 to around 40 degrees. > http://cds.linear.com/docs/en/**application-note/an86f.pdf<http://cds.linear.com/docs/en/application-note/an86f.pdf> > > But: the thermal EMF is only zero against copper. > Most precision integrated (hermetical) cirquits use Kovar. (39uV/K against > copper) > Relay contacts will be either copper berillium or another material. > So in most cases a optimized solder for copper/copper connections will not > be useful. > > On the other side Cd containing solders create very poisonous damps when > being heated. > > With best regards > > Andreas > > > > ______________________________**_________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/** > mailman/listinfo/volt-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts> > and follow the instructions there. >

Ah, that email left the gate before it was ready. Indium still does make Cd bearing solders, just not pastes. Andy Bardagjy bardagjy.com On Thu, May 30, 2013 at 12:51 PM, Andy Bardagjy <andy@bardagjy.com> wrote: > A few months ago I send Indium an email inquiring about low thermal EMF > solders. A good choice is Sn10Pb90, or Indalloy 159. > > Andy Bardagjy > bardagjy.com > > > On Thu, May 30, 2013 at 5:05 AM, Andreas Jahn <Andreas_-_Jahn@t-online.de>wrote: > >> >> Hello >> >> >> 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<http://en.wikipedia.org/wiki/Solder> >>> >>> On Thu, 30 May 2013 04:00:19 +0200, Volker Esper <ailer2@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 >>>> >>>> >> Within LT AN86 Cd60Sn40 is recommended for a limited temperature range of >> 0 to around 40 degrees. >> http://cds.linear.com/docs/en/**application-note/an86f.pdf<http://cds.linear.com/docs/en/application-note/an86f.pdf> >> >> But: the thermal EMF is only zero against copper. >> Most precision integrated (hermetical) cirquits use Kovar. (39uV/K >> against copper) >> Relay contacts will be either copper berillium or another material. >> So in most cases a optimized solder for copper/copper connections will >> not be useful. >> >> On the other side Cd containing solders create very poisonous damps when >> being heated. >> >> With best regards >> >> Andreas >> >> >> >> ______________________________**_________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/** >> mailman/listinfo/volt-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts> >> and follow the instructions there. >> > >

Hi Volker, Look carefully at the graph axis text, it is temperature difference between the two leads, not 0Centigrade to 40 centigrade room temps. M K > From: Andreas_-_Jahn@t-online.de > To: volt-nuts@febo.com > Date: Thu, 30 May 2013 11:05:42 +0200 > Subject: Re: [volt-nuts] cadmium solder alloy for low thermal emf? > > > Hello > > >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@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 > >> > > Within LT AN86 Cd60Sn40 is recommended for a limited temperature range of 0 > to around 40 degrees. > http://cds.linear.com/docs/en/application-note/an86f.pdf > > But: the thermal EMF is only zero against copper. > Most precision integrated (hermetical) cirquits use Kovar. (39uV/K against > copper) > Relay contacts will be either copper berillium or another material. > So in most cases a optimized solder for copper/copper connections will not > be useful. > > On the other side Cd containing solders create very poisonous damps when > being heated. > > With best regards > > Andreas > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

"Andreas Jahn" <Andreas_-_Jahn@t-online.de> writes: > Hello > >>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@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 >>> > > Within LT AN86 Cd60Sn40 is recommended for a limited temperature range > of 0 to around 40 degrees. > http://cds.linear.com/docs/en/application-note/an86f.pdf > > But: the thermal EMF is only zero against copper. > Most precision integrated (hermetical) cirquits use Kovar. (39uV/K > against copper) > Relay contacts will be either copper berillium or another material. > So in most cases a optimized solder for copper/copper connections will > not be useful. I have never understood why it matters anyway. The conductors being soldered together end up in very good thermal contact. So there should be no thermocouple generated by the solder-conductor interfaces (since there is no temperature difference between the ends of the wires being soldered). So if you have copper-solder-copper, say, then the copper-solder junction is microns away from the solder-copper junction and is surrounded by metal. So surely they will be at the same temperature unless there is a huge heat flow. The referenced AN86 even suggests introducing balancing copper-solder-copper junctions, by cutting tracks and bridging with solder. [...] -- John Devereux