Thanks, let me explain
I just bought a "working" hp 8903a from ebay for a low price, but it is showing horrible distortion in the range 20Hz->3Khz (4% at 20Hz, 0.18% at 1KHz, 0.05 at 3KHz, 0.02% 10KHz following) which render it unusable.
I am starting to feel that it is the source the...