LO chain effect on VCO pulling

Hi,

My VCO has a pulling characteristics of 4 MHz pp @ 12 dBr, If my LO distribution chain has reverse isolation like -70 dB, how can I calculate what is the pulling effect at VCO output. So if the load changes at the end of the LO distribution chain, taking into accoutn this 70 dB isolation, how much does the VCO output be pulled?

Initial guess that I have is 4 MHz *10^(-7) = 0.4 Hz

Is this correct?

Thanks

Pulling is not only due to reverse isolation of your LO amplifier. Change of return loss (S11) of the LO amplifier, connected to the VCO output, will give pulling as well.