Ok, lets say you find a suitable cable. What scope do you plan to use? What is the stability of your scope's circuitry? What is the input resistance of your scope?

All of these comments about cable requirements from the OP and still no answers about WHY he needs this unique cable.

 

I have 5 probes with X1/X10 switch (Pomona, Hitachi and noname). Resistance in X1 position is from 220 to 540ohm. I opened few broken probes (1 from HP) and at all cable have few 100ohm resistance of inner conductor.
That's facts.

So you say, but I find your claims highly dubious. Are you sure the instrument you are using is designed to measure low values of resistance? Instruments often "lie" when you exceed their capabilities.

 

So you say, but I find your claims highly dubious.

I don't. Probe cable may not be "normal" coax. I have some raw cable made by HP and it has a single single conductor center conductor -- probably nichrome. See page 15 of this:

http://www.ece.vt.edu/cel/docs/TekProbeCircuits.pdf

 

I don't. Probe cable may not be "normal" coax. I have some raw cable made by HP and it has a single single conductor center conductor -- probably nichrome. See page 15 of this:

http://www.ece.vt.edu/cel/docs/TekProbeCircuits.pdf

Interestingly, to OP is asking for capacitance +/- 10 femtoFarads in the audio range. I just cannot understand what instrument can discriminate this type of variation. I would hope the OP could share more so I could learn, or, so we can offer alternatives. I personally think alternatives must exist because nobody here seems to understand why he needs probes with specs that are not available - not even close!

 

So you say, but I find your claims highly dubious. Are you sure the instrument you are using is designed to measure low values of resistance? Instruments often "lie" when you exceed their capabilities.

The coax used with scope probes has a very small diameter center conductor made of resistance wire. The probe that came with my Agilent DS50304 measures 130 ohms from probe tip to center pin of the BNC connector, with probe set to 1X.

Have you measured any of yours recently?

 

It is clear from his posts that the OP intends to use the cable to measure small capacitance values some distance from the measurement circuit and the shunt capacitance of the cable would use up some of the test circuit's dynamic range (inferred) and that drift of that capacitance would throw off the calibration. He said he cannot disclose more, so we should respect his need to keep some details confidential.

It appears that the cable the OP seeks may not be obtainable. If that were the case, then one solution that might be acceptable would be to put the converter circuitry that is "intimate" with the capacitance being measured onto a compact test head that is then connected to the rest of the instrument or system via cable.

An aside:
This is a interesting discussion about scope probe cables. The high resistance of the center conductor answers the nagging question of why scope probe cables don't act like open transmission lines. RichardO, thank you for posting the link to that old and wonderful Tektronix document.

 

@DickCappels 1st one who know what I want.

Measurement circuit can't be placed close to the measured objects.