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The Tektronix P6451 is an 8+1 channel active logic probe designed for use with the 7D01, 7D02, DL502, LA501A, WR501, 308, 318, and 338. It presents nine differential ECL signals back to the input section of the analyzer − 8 data channels, plus a 9th channel that is used either as a clock or as a qualifier.

Channel equivalent circuit (click to enlarge)

The P6451 has the ability to set different threshold voltages for each of three channel groups − 1-4, 5-8, and the 9th (called 'C' in the manual).

The only active components are two 155-0137-00 custom hybrid pre-amp/comparator modules containing comparators with FET inputs and differential ECL outputs that can drive terminated 100 Ω lines. The instrument input would contain differential ECL receivers like the 10115 or 10216.

The P6451 uses the P64xx-family 10-wire input lead harnesses with 0.2"-spaced connectors. It is also possible to use standard jumper wires with pins, sockets or clips on the other end for connecting inputs.

There are two versions of the P6451:

  • Part No. 010-6451-02/-03 has a straight connector, and is intended for 7000-series and TM500 plug-ins (e.g.7D02, SA501) and 8550 series development systems.
  • Part No. 010-6451-05/-07 has a 90° connector and is intended for 300 series analyzers (e.g. 308). The -07 also has additional series resistance in the inputs for damping ringing caused by a lead set.

P6458 is a 4-channel version for the SA501, which works with either model.


Maximum Voltage ±40 V nondestructive
Input impedance 1 MΩ // 5±1 pF (without input leads)
Delay time 17±2 ns with ±1 V input and threshold at 0 V
Power 5 V, 260 mA