131

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The Tektronix Type 131 is a current probe amplifier used only with the P6016 current probe. Type 131s were never given serial numbers, instead, they were produced chronologically in "Models." Models 1 thru 3 looked alike, while Model 4 got a redesigned enclosure like that used later by the Type 134.

Key Specifications

Sensitivity	1 mA/Div to 1 A/Div, 1−2−5 (scope input fixed at 50 mV/Div)
Noise	0.1 mAp-p
Risetime	20 ns (eq. 17 MHz −3 dB bandwidth)
Lower frequency limit	50 Hz
Delay time	32 ns typ.

(all specifications are overall values including the P6016 probe)

Connectors

All models of the 131 use a BNC input connector.

The vast majority of 131s, including all the Models 1 thru 3, have a UHF output connector. 131 Model 4s with UHF outputs were Tektronix #015-0029-00.

A few very late 131 Model 4s were supplied with a locking BNC output connector, as Tektronix #015-0050-00.

Internals

All four Type 131 models used PNP transistors, thus requiring a negative power source. Models 1 thru 3 were hard-wired to their separate minus ~19 V power supplies, while Model 4 got a power supply, 015-027 for 115 V_AC, with a proprietary Tektronix coaxial connector. The center pin of the Type 131 Model 4 power supply connector is grounded, so the outer contact is ~19 V negative. Note that the 015-0058-01 power supply for the Type 134 uses the same connector with the same relative voltage levels (center conductor ~19 V more positive than the outer contact) but the negative outer contact on the Type 134 power supply is held close to ground. So the Type 131 Model 4 will only work with the correct 015-027 power supply.

Using the wrong power supply with either amplifier type will short circuit the power supply output. Tektronix claims that this will not damage the Type 134 power supply (015-0058-01) if connected to a Type 131. Damage to the Type 131 015-027 power supply seems likely if it is connected to a Type 134. Damage to the amplifier itself is unlikely either way.

Power supplies for Type 134s are labeled "POWER SUPPLY FOR TYPE 134", while those for Type 131 Model 4 have no marking other than Tektronix and 015-027. All Type 131 power supplies have the AC line connector built onto the end of the power supply housing. Early 134 power supplies share the same construction, while later 134 power supplies came with a ~1 m AC line cord and plug.

Accessories

The Type 131 Model 4 could be purchased with a battery adapter instead of a power supply. The 131 / battery adaptor set was sold as a Tektronix 015-026. The adaptor was simply a pair of wires, ending in fork lugs, that came together in a socket that mated with the 131 Model 4 power cord. See here for more information

Pictures

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  Type 131 Model 4 Front

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  Type 131 Model 3 Front

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  Type 131 Model 4 Side View

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  Type 131 Model 3 with P6016

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  Type 131 Schematic, Models 1-3

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  Type 131 Model 3, with attached power supply

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  Type 131 Model 3

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  Type 131 Model 3

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  Type 131 Model 3

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  Type 131 Model 3

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  Type 131 Model 3

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  Type 131 Model 3