[volt-nuts] Datron 1065 and 1071 differences

Simon McNally simon.mcnally at sky.com
Sun May 25 13:15:47 EDT 2014

Hi guys.

I have been looking at the service manuals for the Datron 1061 and 1071 
to try and discover the hardware differences between these models. What 
i have discovered so far is that several of the pcbs are identical 
barring maybe a few headers not fitted. These are the psu, gpib, l.h. 
pcb and the centre PCB. There is no R.H. PCB. I have not checked the ac 
or ohms pcbs yet but they do look like they are the same.  The digital 
pcb has the 3rd eprom position unpopulated. I have mostly looked at the 
analogue PCB.

The Analogue PCB does not have any of the current measurement parts 
fitted which is no surprise as it was not offered as an option. The 
potentially most interesting part revolves around the references. As the 
1071 is 7 1/2 digit the references need to be orders of magnitude 
'better' than the 1065 which is 5 1/2 digit.  This is achieved by having 
more resistors in the resister network to set the voltage from the 
zener.  The boards are the same but the resistors R41 - R45 and R88 - 
R92 are all fitted to the 1071, whist only R42 - R43 and R89 - R90 are 
fitted on the 1065, 1061, and 1061A. Both the service manuals describe 
the step to set the reference voltage, however the voltage is set to a 
order of magnitude better on the 1071.

The values on the 1071 are R41=169R 1% 10ppm , R42=84R5 1% 15ppm , 
R43=42R2 1% 50ppm , R44=21R0 1% 50ppm , R45=10R5 1% 50ppm , R88=169R 1% 
10ppm , R89=84R5 1% 15ppm , R90=42R2 1% 50ppm , R91=21R0 1% 50ppm , 
R92=10R5 1% 50ppm

On the 1061 et all:- R42=196R 1% 15ppm, R43=97R6 1% 50ppm, R89=196R 1% 
15ppm, R90=97R6 1% 50ppm

The drawing are in the manuals which can be downloaded from KO4BB's 
site. I have not found any other differences yet. Im not sure if adding 
these resistors and nailing down the reference will be of any benefit to 
my 1065, and could possible introduce some additional drift as the 
current reference parts have stabilised together for 30 years. It would 
be interesting to find out though at some point.


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