Peak-to-peak voltage of WRL-10534?
14 dBm is 10^1.4 = 25 mW.  Assuming an output impedance of 50 ohms, P = V^2 / R.  0.025 W * 50 ohms = 1.25.  sqrt(1.25) = 1.12 Vrms.  Vrms = Vpk-pk/sqrt(8), so Vpk-pk = 3.16 V.