Topband: How to measure the resonance of a tower?

[DM4iM]

Topbanders,
i plan to try shunt-feeding my tower again, now with more experience and 
better measurement gear.
I'm still far from being an expert, so here are a few questions:

I have a Dip-Meter, Noise-bridge and access to a DL1SNG Vector 
Antenna-Analyser.

How can i measure where the tower resonates?
Has someone tried to use a SteppIR as a variable capacitance hat?

All input welcome.

-- 

73,
Martin DM4iM