Re: [volt-nuts] LTZ1000A Heater Temp (Ben Clark)
Jan, Would you please post the link to your plot? I searched but haven't found it yet. thanks, Randy Evans On Thu, Feb 12, 2015 at 3:51 AM, Jan Fredriksson wrote: > I posted a plot of calculated resistor values versus temperature in > the LTZ1000 thread on the EVV blog yetserday. Email me if you can't > find it. > > I guess the 3458A was specified to be used at north pole and desert > heat, that's why they have such a high temperature setting. They could > have a "laboratory version" and a "field version" of the reference > > I have a NI-4071 PXI DMM with a LTZ1000 and it uses 14.3 ratio to > fulfill the PXI specified temperature range. Still higher than optimal > for stability but the temperature in my PXI rack is typically 40C at > 20C room temperature. > > my2C > ___ > 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] HP 3458A Vref LTZ1000 question
I have a spare REV A Ref Board, 03458-66509, from a 3458A. I need to know if the LTZ1000 reference IC is a 1000 or a 1000A chip, as they have different temp set points and thermal losses. The LTZ1000 on my board only has the HP part number, 1826-1860. I have an HP X-ref, but this number is not listed. If anyone knows for sure which version of the LTZ1000 this is, it will help many besides myself. Best, Dick Moore ___ 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.
Re: [volt-nuts] Zener, IC, references - which one
Am 13.02.2015 14:31, schrieb Andrea Baldoni: Hello All. I would like to experiment with voltage references by putting them into a ovenized chamber (a DOCXO with a broken crystal) with their bias and buffer circuitry. The final goal will be to have the way to calibrate the HP 34401 as well as other instruments, but now I want more to "learn by doing". The chamber has his own heater so I'm not planning to use LTZ1000 or LM399 unless I leave their internal one unconnected. Between the ones I am able to find new on the market, there are the zener diodes 1N829A (6 EUR new, 8 EUR NOS), the LM399H (12 EUR), the LM329BZ (4 EUR), while the LTZ1000 and the SZA263 are available used. I'm more concerned with long term stability than TC because everything will lie in a very constant temperature oven; I would like to use more expensive devices only if they have some advantage (IE, the LTZ1000 is really better than 1N829A or the advantage come by the fact it has his own oven?). Also, about external circuitry, what op amp do you suggest? A chopper one is probably not needed, always because it lies in a oven, and it may add noise. And about resistors? Yes, there are Vishay Z-foil, but there are other with worse tempco but same long term stability? Best regards, Andrea Baldoni ___ 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. Hi Andrea, some comments: A LTZ1000A voltage reference will not need an outer oven at all. Elevated outer temperature makes a elevated internal temp necessary and you can expect this to make long term drift worse due to aging. The LTZ just as everyone else likes to be as cold als reasonable possible. The circuit according to datasheet and good temperature setpoint give optimum results. The LM399s are running very hot already, so this negative effect might not show up so much. If I would have the OCXO can, I would stick several LM329 in it. Also, if you want a 7V->10V stage with a opamp and resistive divider, these might benefit from the oven if they are inside. Dont use the HP10544 oven, as it is using PWM and I think that is bad around a voltage reference. =) Best regards Hendrik ___ 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] Zener, IC, references - which one
Hello All. I would like to experiment with voltage references by putting them into a ovenized chamber (a DOCXO with a broken crystal) with their bias and buffer circuitry. The final goal will be to have the way to calibrate the HP 34401 as well as other instruments, but now I want more to "learn by doing". The chamber has his own heater so I'm not planning to use LTZ1000 or LM399 unless I leave their internal one unconnected. Between the ones I am able to find new on the market, there are the zener diodes 1N829A (6 EUR new, 8 EUR NOS), the LM399H (12 EUR), the LM329BZ (4 EUR), while the LTZ1000 and the SZA263 are available used. I'm more concerned with long term stability than TC because everything will lie in a very constant temperature oven; I would like to use more expensive devices only if they have some advantage (IE, the LTZ1000 is really better than 1N829A or the advantage come by the fact it has his own oven?). Also, about external circuitry, what op amp do you suggest? A chopper one is probably not needed, always because it lies in a oven, and it may add noise. And about resistors? Yes, there are Vishay Z-foil, but there are other with worse tempco but same long term stability? Best regards, Andrea Baldoni ___ 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.
