I recently got in an ESI DB877 8 decade resistance box (12 Megohms at 0.1 ohms/step). This box is chock full of 0.01% wire wound resistors (1R and 5x2R resistors per decade) and a pair of nested four gang switches/dials. The 1K resistor was pretty much toast. I replaced it with the 900.98 ohm and 100.02 ohm resistors from a Tektronix 067-0503-00 precision DC divider (paralleled with a selected 1 Meg resistor). That resistor is now within around 0.0005%. The 10K resistor was also off, reading around 10015 ohms. Paralleling it with a selected resistor pair also got it to around 0.0005%. All is well with this wonderful little box and all values are now well within spec (0.01%). Most are under 0.003%. However, things could be better for this volt nut. The 100K and 5x200K resistors are all around 8-9 ohms high. Does anybody know of a cheap source of 1 to 5 gohm resistors (actually 1.250 gohm, 1x2.500 gohm, and 4x4.000 gohm, would be best and would get that whole decade under 0.001%)? Mouser/Digikey/etc have them for around 4 bucks a pop... cheaper is better... Now, if I could also find a -0.0382 ohm resistor to cancel out the zero ohm lead/switch bias... ---------------------------------------- _________________________________________________________________ Windows Live™: Keep your life in sync. http://windowslive.com/explore?ocid=PID23384::T:WLMTAGL:ON:WL:en-US:NF_BR_sync:082009

I picked up a DB-877 at the De Anza swap meet in the bay area a few years ago. It was grubby but a bargain at $40! Works perfectly after a bit of cleaning and some lubrication of the concentric shafts. These a realy good units, very compact for 8 decades. 0.01% is good enought for me as a decade box. The swap meet is well worth a vist. Dispite many vists to the bay area only on coincided with the meet. Robert G8RPI. --- On Sun, 16/8/09, Mark Sims <holrum@hotmail.com> wrote: > From: Mark Sims <holrum@hotmail.com> > Subject: [volt-nuts] More Precision Resistors > To: volt-nuts@febo.com > Date: Sunday, 16 August, 2009, 2:26 AM > > I recently got in an ESI DB877 8 decade resistance box (12 > Megohms at 0.1 ohms/step).   This box is > chock full of 0.01% wire wound resistors (1R and 5x2R > resistors per decade) and a pair of nested four gang > switches/dials. > > The 1K resistor was pretty much toast.  I replaced it > with the 900.98 ohm and 100.02 ohm resistors from a > Tektronix 067-0503-00 precision DC divider (paralleled with > a selected 1 Meg resistor).  That resistor is now > within around 0.0005%. > > The 10K resistor was also off,  reading around 10015 > ohms.  Paralleling it with a selected resistor pair > also got it to around 0.0005%. > > All is well with this wonderful little box and all values > are now well within spec (0.01%).   Most are > under 0.003%.  However,  things could be better > for this volt nut.  The 100K and 5x200K resistors are > all around 8-9 ohms high.  > > Does anybody know of a cheap source of 1 to 5 gohm  > resistors (actually 1.250 gohm,  1x2.500 gohm,  > and 4x4.000 gohm,   would be best and would > get that whole decade under 0.001%)?  > Mouser/Digikey/etc have them for around 4 bucks a pop... > cheaper is better... > > Now,  if I could also find a -0.0382 ohm resistor to > cancel out the zero ohm lead/switch bias... > > ---------------------------------------- > > > _________________________________________________________________ > Windows Live™: Keep your life in sync. > http://windowslive.com/explore?ocid=PID23384::T:WLMTAGL:ON:WL:en-US:NF_BR_sync:082009 > _______________________________________________ > 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. >