I am not sure if Fluke had matched tempco spare parts, but you can look at some NOS resistors from Fluke on ebay. They may be a good start and some of the pricing isn't bad.
Todd On Thursday, July 17, 2014, Randy Evans wrote: > Frank, > > The high cost is my concern, although high performance demands high price > typically. I am trying to double the voltage reference from either an > LM399 or LTZ1000, hence the need for precision matched resistors for a x2 > non-inverting amplifier (using a LT1151 precision op amp). An alternative > I am investigating is using the LTC1043 in a voltage doubling circuit as > shown in Linear Technology app note AN 42, page 6, Figure 16. It states > that Vout = 2xVin +/- 5 ppm. I am less concerned about the absolute > accuracy than I am about the long term stability. I assume that a high > quality capacitor is required (low leakage, low ESR, low dielectric > absorbtion, etc.) but the circuit does not appear to be dependent on the > absolute value of the capacitors. I'm not sure if the two 1uF caps need > to be matched. If they do then that would be a show stopper. > > Does anyone have any experience using the LTC1043 in such a circuit? > > Thanks, > > Randy > > > On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach < > [email protected] <javascript:;> > > wrote: > > > Randy, > > > > resistor matched in T.C. are extremely expensive, as the manufacturer (or > > yourself) would have to select these from a batch of many samples. > > > > reistors with very small T.C. (<1ppm/K) would do the job also, but they > > also need to be stable over time, in shelf life opereation mode, i.e. > > P<10mW. > > > > That means, you need those hermetically sealed VHP202Z from Vishay, T.C. > > is typically < 1ppm/K and they are stable to < 2ppm over 5years. But they > > cost already 80€ each, depending on tolerance. > > > > I made a longterm observation of these and found these parameters > > confirmed. > > > > Frank > > _______________________________________________ > > volt-nuts mailing list -- [email protected] <javascript:;> > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/volt-nuts > > and follow the instructions there. > > > _______________________________________________ > volt-nuts mailing list -- [email protected] <javascript:;> > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
