How to verify the VCO peformance?

Hello guys,
I'm trying to design a local oscillator using a Z-comm VCO+National's PLL. Now, the loop filter could lock and give me a stable frequency output. I checked the phase noise performance of oscillator, there's hump from 300Hz -30Khz.

To figure why this hump comes, firstly, I want to make sure the VCO is working under the pefermance which is specified by the datasheet. I have a bit suspect on the VCO"s power line noise to ruin the performance.

A method I try to verify this is to break the output of loop filter and tuning line of VCO, and attach a (AA+) battery to tuning line, meanwhile, just provide power to the VCO. With this method, I found that even the battery output is not as stable as expected. I could found the VCO frequency output drift slowly, or maybe this due to frequency drift of spectrum analyzer. Anyway, the measured phase noise under this condition is worse about 11dB than specified by datasheet.
like this.

I"m wondering whether there's better way to figure out the performance of VCO, or whether the VCO on my board works at specified performance?

Yep, that is pretty nasty! You would have to tell us all the circuit and programming details for useful comments. But, what is the clock phase noise?

The hump maybe result from your PLL filter bandwidth, your bandwidth maybe 30KHz? If so, try to reduce the bandwidth to about 1KHz.