The Tek terminal strips, used in all the tube and hybrid scopes (through the 547) had silver plating on those ceramic standoffs. The silver bearing solder was used to prevent the plating from leeching off and the parts coming adrift. No thermal issues in those, they drift like crazy. You just live with it. Here is more on the issue of thermal emfs : http://www.edn.com/design/analog/4342865/Minimizing-thermocouples-maintains- 20-bit-DAC-precision > > Joseph, > > The only place where I have seen low thermal solder used was in the OLD > TEK tube scopes in only one special place. Those OLD tube scopes had a > few ceramic standoffs that had a number of cupped spaces with metal > surfaces bonded with some kind of glue that could not take a lot of > heat. These standoffs were used, at the time, for providing a high > impedance, low leakage connection point. > > We are talking in the 1950 and 1960's time frame. Later in time TEFLON > became the choice for such use. > > Bill....WB6BNQ > > > Joseph Gray wrote: > > >Volker, > > > >I came across a couple of old Fluke differential voltmeters that need some > >work. I thought it would be best to use low thermal EMF solder on these. > > > >Joe Gray > >W5JG > > > > > > > >On Mon, Aug 12, 2013 at 10:39 AM, Volker Esper <ailer2@t-online.de> > wrote: > > > > > > > >>Sorry, Joe, if my question was mistakable. I wanted to know your > >>application. Maybe I'd recommend not using a special solder alloy rather > >>than going the long way of aquiring it. > >> > >>I give you an example: When fixing a 6.5 digit DMM (HP34401A) I wasn't > >>sure if I might use a special alloy to solder the pins of an input relay. > >>In the end I did not. Comparing this fixed unit to a second one in several > >>automated 24 hours tests with varying room temperatures, there seem to > be > >>no measurable differences between the two. So in this case it appears to > be > >>of no great importance using a special solder. > >> > >>Enthough the thermoelectric voltages at these pins are not negligible and > >>therefore have to be considered, other effects obviously are of much > more > >>effect. So, as I mentioned, using a special soldering alloy drops in the > >>priority list. > >> > >>Now, that I'm curious, please let us know, what you are using the solder > >>for. > >> > >>Volker > >>DF9PL > >> > >> > >>Am 12.08.2013 15:06, schrieb Joseph Gray: > >> > >> > >> > >>>As I asked in my original message, I'm trying to find out where I can buy > >>>a > >>>small quantity of rosin-core 10/90 (tin/lead) solder. I don't want to buy > >>>it in bar form from China. > >>> > >>>Joe Gray > >>>W5JG > >>> > >>> > >>> > >>>On Mon, Aug 12, 2013 at 3:17 AM, Volker Esper<ailer2@t-online.de> > wrote: > >>> > >>> > >>> > >>> > >>> > >>>>sorry, spelling mistake: > >>>>"What do you _want_ it for?" > >>>> > >>>>Remember, those solder alloys are optimized for a specific alloy > >>>>combination only, e.g. Cu-Cu. > >>>> > >>>>Volker > >>>> > >>>> > >>>>Am 12.08.2013 10:39, schrieb Volker Esper: > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> > >>>>>Hi Joe, > >>>>> > >>>>>What are you looking for, Cadmium-Solder, or Sn10Pb90, which is > >>>>>Stannum/Plumbum-only? > >>>>> > >>>>>And what do you what it for? In (very high) precision applications > there > >>>>>are so many issues to consider that the solder doesn't appear to be at > a > >>>>>high priority... > >>>>> > >>>>>Volker > >>>>> > >>>>> > >>>>>Am 12.08.2013 00:38, schrieb Joseph Gray: > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>>>Reading through the archives, I saw that there was some discussion > >>>>>>about > >>>>>>a > >>>>>>safer alternative to cadmium-based solder. The low tin, high lead > alloy > >>>>>>was > >>>>>>recommended as a good low-thermal EMF substitute. However, I did > not > >>>>>>see > >>>>>>any recommendations on where to buy some of this. > >>>>>> > >>>>>>I just did some searching and all I come up with is bar solder, mostly > >>>>>>from > >>>>>>China. Where can I buy a small quantity of rosin-core 10/90 solder? > >>>>>>Mouser, > >>>>>>which is my preferred vendor certainly didn't list any. I would think > >>>>>>that > >>>>>>even 1/2 pound would last me a lifetime. > >>>>>> > >>>>>>Joe Gray > >>>>>>W5JG