DIY Open Source LM399 10V Voltage Reference

while working on a project i needed a really stable voltage reference so i made my self  LM399 based 0.5 ppm/ C 10V refernce.

LM399 is nice shunt reference chip , Although initial accuracy is only 2% but accurancy does not matter , what matter is stability. Because i have recently calibrated Agilent 34465A 6.5 digit multimeter , i can easily find out absolute value. 

With 0.5 ppm/C and 10V range , its translate to 5uV /C. At this range of temperature stability it is way beyond what my Agilent 34465A can measure.

Agilent 53132A 53131A 53181A DIY Open Source 3Ghz Channel Option 030 Board

As mentioned my Open source Agilent OCXO upgrade post, I mentioned, I have bought a Agilent 53132A a 12 digit universal counter, more capable than commonly known 53131A 10 Digit Counter. Both are really nice units though.

unit i have bought did you have ultra stable oven oscillator so i made oven board, this unit also have option for third channel, my unit did not came with any third channel.. which is capable for frequency up to 12.5 Ghz with correct option installed. These optional board contains RF Gain blocks and frequency prescaler chips. many people have made there own DIY units but none of the is open source. So i have to make one open source DIY Design.

Although i did not needed any RF counter, but i still decided to make my self 3Ghz prescaler. Because when i was doing oven board so it was no too much hassle to make one more board.

here is how board looks