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The 1432P Decade Resistor consists of a combination of Type 510 Decade Resistance Units mounted on an aluminum panel and encased in a welded aluminum cabinet. Ample mechanical strength is assured by the use of 3/16-inch panel and 1/8-inch walls. A considerable reduction in volume is realized--1/8-inch aluminum replacing 5/8-inch hardwood reduces both width and length by a full inch. Excellent electrostatic shielding and good thermal characteristics are also assured by this construction. A separate binding post for connection to the case is provided, thus permitting shielding of the resistors whether used grounded or ungrounded. Other time-proved features, such as engraving the current carrying capacity of each decade on the panel, are included.
Mere accuracy of adjustment, however, is not sufficient in a laboratory resistor. The stability of resistance value is equally important, if not more so. The resistor units used in General Radio Decades have a stability considerably better than the accuracy of adjustment and can be expected to stay within their specified tolerances well beyond the one-year warranty period.
Both the improved accuracy and greater stability result largely from the use of new resistance alloys made available during the past decade. These improved alloys have a low temperature coefficient that is substantially constant over a wide range of operating temperature, a high specific resistivity low thermal emf to copper, and a remarkable insensitivity to changes in resistance induced by mechanical strain. Furthermore, fine wire drawn of these alloys is much less susceptible to deterioration under conditions of high humidity than are the older alloys.
The new alloys are used in the 100Ω, 1 kΩ, 10kΩ, and 100 kΩ units. Manganin is still used in the lower-resistance units, where wire diameter is larger and atmospheric conditions are not so significant in determining long-time stability.
Groups of these resistance units, used as working standards in our shops and laboratories, have shown a stability of better than 0.01% under constant usage over a period of years.
The 100,000-ohm unit is a new design, replacing the spool-wound resistors formerly employed for this resistance value. The winding form is a thin mica card of the type employed successfully for over twenty years in 1000-ohm and 10,000-ohm units. The high-resistivity alloy, in a wire having a diameter of one-thousandth of an inch, allows the desired resistance to be wound on a form of substantially the same size as used for lower-resistance units. These new 100,000-ohm cards result not only in improved performance but also in a reduction in the price of the Type 510-G Decade Resistance Unit, which uses ten of these cards.
Model No
1432P
Condition
Used
Manufacturer
General Radio
30+ Years in Business
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30+ Years in Business
Secure Payments
Sell Test Equipments
Knowledgeable Staff
On-site Lab
