A. Kelvin-Varley. Voltage Divider. Instruction Manual. P/N mm (8) In the event of failure of a product covered by this warranty, John Fluke Mfg. Co., . The Fluke A Kelvin-Varley Voltage Divider generates V and 11W of power. A models provide an absolute linearity of ppm, a temperature. Find great deals for Fluke A Kelvin Varley Voltage Divider Shop with confidence on eBay!.

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The switches have multiple wiper contacts to provide stable low contact resistance.

May the Volt be with you. Disclaimer Redistribution and use of this article or any images or files referenced in it, in source and binary forms, with or without modification, are permitted provided that the following conditions are met: Our unit still have old-style Fluke logo, bit yellowed switches and of course dirty connectors: As was predicted not very long time agocomplete Fluke A standard got into out hands finally.
Well, our quest with Decade A does not end so quick with only bad wiring, as even after reassembly of wiring properly, divider does circuit does not work as expected. Later decades only fine-tune resistance of primary resistors in decade A. Wiring around decade B Image Internal calibration switch Little board with beautiful Fluke-made teal resistors mounted just above the oil tank from the top side.
Hermetic pass-thru terminals, color coded wires, filling port. Oil-filled main decade A. Brief summary table presented here, based on Instruction Manual. This instrument is… Image 7: Specification summary for Fluke A So essentially, if we skip important construction and design details for sake of simplicity, Fluke A is just a fancy potentiometer.
Bottom PCB have long array of low-resistance wire-wound resistors, few variable 1-turn potentiometers and multi-turn trimpots.
The KVD Kelvin-Varley Voltage divider employs precision resistors which have been aged, temperature and power cycled to maximize long-term stability, and matched to minimize temperature and power coefficients effects.
All other conductors within the instrument, as well as the solder employed, 720aa no metals or junctions that could contribute to thermal emf problems. In no event shall the author, xDevs. Incorrect wiring on decade switch. Also PCB s are more usual modern green flue type there. This reveals that all decade A resistors are wired incorrectly by one position counter-clockwise from switch rear view. Original ones were made of fragile acrylic plastic and cracked already: Fluke A front and rear features There are no connectors, vent openings or anything else on sides and rear of the instrument.
Fluke A front and rear features. Credits for help and contributions which make this project possible: Dluke harness, all fixed in place. Plastic shafts used to rotate decade switches were replaced as well.

So essentially, if we skip important construction and design flule for sake of simplicity, Fluke A fluoe just a fancy potentiometer. There are no any active thermal regulation inside A, so Fluke engineers went other way around thermal stability and performance.
Our unit still have old-style Fluke logo, bit yellowed switches and of course dirty connectors:. Little board with beautiful Fluke-made teal resistors mounted just above the oil tank from the top side.
Fluke 720A Kelvin Varley Voltage Divider 1604057
If you would like to support us by making a donation please click the Paypal button: To achieve this ratio, calibrated HP A multimeter will be used. Later ones are accessible from front panel to implement calibration functionality for decades A and B.
One of our contributors, Todd sent few photos of something what supposed to be Fluke A, but with very different internals! Maybe except screw or two… Internal switch for calibration for third decade. It has a 1. Inside bottom side Bottom side reveals some serious touch on details, with oil-filled resistor chamber for most critical first decade A. It is a highly accurate, stable, and linear primary ratio standard suitable for use in many applications requiring known voltage or current ratios.
Also connection to input and output binding posts has got my attention, as soldering does not look very good. If reading correct, date-code on on decade A switch is 6th weekand resistors on A trimmer board are 37th week And as expected, after decade switch replacement unit came back to life. The KVD features a built-in Wheatstone bridge self-calibration circuit so that the unit may be calibrated with a minimum of external instruments and without requiring another voltage divider.
If you willing to contribute or add your experience regarding any instruments repairs or provide extra information, you can do so following these simple instructions.
| Fluke A Kelvin-Varley Divider restoration
None of this would happen without great volt-nut community all over the globe. Maximum voltage and current limits are indicated as well.
Function switch have many long rotary sections. The KVD Kelvin-Varley Voltage divider incorporates a number of advanced features making for convenience and high performance. On sub-ppm performance levels there are no insignificant details, so great care was taken to guarantee design targets.
