Fluke 5520A/SC300, 600, 1100 Matched Cable Use

[Hawaii596]

So according to the manual for use and calibration of the Scope options on 5500A and 5520A, they prescribe use of the matched cable that comes with it.  I am calibrating an SC600 Scope option right now, and in the cal procedure it requires it, and in the operations manual, it requires it. 

However, no one appears to be using them.  Using a proper matched cable during an NAPT oscilloscope proficiency test, I believe it was a 3 Vpp, 600 MHz (don't remember freq for sure).  But with use of the proper cable, it made the difference between a reading at the upper BW freq of about 2.99 Vpp with proper cable, and about 2.72 with any other cable.  I included enough MU to allow me to pass.  But when I read the results of all the other participants, and NAPT, their readings matched pretty much readings made with the wrong cable.

Also, I send my two accredited 5520A's, both with SC1100 Scope options to Fluke.  I don't send the matched cables, and they don't ask for them (even though when I send my 5720A with Wide Band, they do ask for that cable).

I have the impression that no one is using the correct cable as spec'd in the manual - including Fluke.  Is this perhaps because everyone doesn't use the original matched cables any more, and the world has adapted to that?

Just wondering if anyone has any thoughts on this.

[scottbp]

My question is how does Fluke do the matching? What are they matching it to? I know there has to be more to it that simply adding ferrite cores to the cable.