I am using a E4432B RF signal generator. It is pretty old. I recently connected the signal generator to a spectrum analyzer to see if I really get the signal that I am outputting. Mostly, the spectrum analyzer readings are pretty accurate, but at times (very rare), I get SA (spectrum analyzer) readings that are completely absurd, like 1-1.5 dBs far from average. For example, if I program the signal generator to output -67 dB, and I expect a SA reading between -67.5 to -67.8 dB, that is what I get in the most part, but at times, I also get something like -66.6 dB. And it happens mostly when I am switching between signals. Like if I do a sweep from -63 to -67 dB and change the level by 0.5 dB each time and run if overnight, rarely I get those absurd data points at different signal levels. I was wondering what is the reason for this. Is the attenuator a problem here, or what else can it be? I tested the cable with another signal generator and that test indicated that the cable is good.