The PLL is unlocked and the instrument is trying to interpret various IF signals it receives from its several converters. I suspect that some DC offset signal from a mixer is wrongfully interpreted as a tone. Once the PLL is locked, this issue is resolved automatically.
Before I ask my question, I need to say, that I have not done much with RF, but find it fascination.
So, may be the answers are obvious to an RF specialist...
1)
I have an older HP Spectrum Analyzer Model 8596E.
This one also shows a peak at the very beginning of the sweep, when it starts the sweep at 9 kHz.
(Noting connected to the input)
Is it possible that this is inherent to HP spectrum analyzers?
I get a -1dBm at -100Hz
(see pictures)
2)
Why can I set my HP Spectrum Analyzer to start sweeping at a negative value?
i.e. -100 Hz
3)
And one more question, if you know the answer....
Why do most of these spectrum analyzers have a listed start frequency of 9kHz?
Why not 5kHz or 10 kHz or any other value?
Even some HP RF signal generators start at 9 kHz?
Was this an arbitrary selection by HP at the time or is there a significant technology reason behind this number?
Thanks for all your great videos.