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HP 8590A RES BW NOISE FAIL 100000 on Confidence test - Troubleshooting?

Question asked by andersg on Feb 21, 2015
Unit seems ok otherwise. Noise floor in the installation manual test is fine, but it gives the above error on the confidence test.I sort of understand what the error indicates, ie:

"The test compares the noise-floor amplitude of each
resolution bandwidth to that of the next, narrower
resolution bandwidth.
If the error message RES-BW NOISE FAIL is
displayed, a decrease in the noise floor amplitude did
not occur when the test switched to the narrower
bandwidth. The test displays the narrower
bandwidth as the test failure and displays all
bandwidths that fail."

But with what parameters are that test performed? To test i did set CF to 300MHz, VBW to 30Hz, SCAN to 0Hz, Atten to 0dB and REF to -80dB (ie same as for the manual test. I then did a single scan with varying resolution bandwidths, with the internal generator connected and with the input connected to a 50 ohm terminator. The results are below:

RES BW    GEN    50ohm
1kHz         -119,77 -119,25
10kHz       -109,22 -109,79
100kHz     -91,29   -91,79
1MHz       -60,66    -89,88
3MHz          none   -86,99

Ny "none" i mean offscale. Is this normal? Forgive my ignorance. It is my first SR, not counting the quick hack job I once did with a swept Tv tuner :)