[volt-nuts] Fluke 335A/D

m k m1k3k1 at hotmail.com
Sun Dec 16 15:49:35 UTC 2012

Hi Frank,

where does the Fluke 3335b sit in the range of specifications?

M K 

> Date: Sat, 15 Dec 2012 12:38:00 +0100
> From: frank.stellmach at freenet.de
> To: volt-nuts at febo.com
> Subject: [volt-nuts] Fluke 335A/D
> Hello,
> according to the different documents for the 335A and the 335D, the 335A 
> had a mechanical chopper for the main error / chopper amplifier, and the 
> voltage reference consisted of a discrete (separate) zener and 
> transistor in an oven.
> The 335D already had the FET chopper and the TI or Motorola 'reference 
> amplifier', i.e. zener and transistor on-one-chip.
> Both versions obviously have the opto-chopper for the differential 
> voltmeter amplifier.
> This is the same design as in the 845AR/AB.
> The 332D therefore is preferred over the 335A, and over the 332B, if the 
> differential voltmeter is needed.
> Maybe it's easily possible to increase its sensitivity and damping to 
> 1µV instead of 10µV.
> I own a defective 332B/AF version (possibly AF = Air Force), which is 
> built the same as the 335D, only without the additional differential 
> voltmeter.
> Its big problem is the high voltage pre regulator, as the supressor 
> Zener (CR14) and the switching transistor (Q1) are not available any 
> more. Therefore, a 5440/5442 was the best choice, especially as it has 
> Autocal; all the others need additional equipment for linearity and 
> range calibration.
> The HP 740B is also nice unit, but is has several neon bulb based 
> opto-choppers, which may be a big pain if they go defect.
> Frank
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