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I'm experimenting with the 434 MHz RF Link transmitter (WRL-10534) from SparkFun. I'd like to determine the peak-to-peak voltage of the RF output, but I don't have access to an oscilloscope that can measure this signal. The datasheet for the transmitter says that the output power is 14dBm. The transmitter's supply voltage ranges from 1.5 ~ 12V so I assume the 14dBm spec is full power when operating with a 12V supply.

Can anyone suggest how I can determine the peak to peak voltage of the RF output?

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If you want to try and measure it you could use fast diodes and a peak detector which is basically just a capacitor like 100pF with a 1Mohm resistor across it.

I mean really fast diodes of course not standard 1N4148 or 1N914 type things. Even BAS16 isn't really man enough for the job (probably). Look for RF diodes that can be used in demodulators up to and over 1GHz. Maybe like what PIN diodes that Skyworks make here

Basically couple your antenna feed to a 50 ohm load (or the antenna) and use a circuit like this: -

enter image description here

There will be one diode drop voltage lost which will probably amount to about 0.5V. Use a DVM across the RC network to measure the DC voltage. The reading plus 0.5 volts will be the peak voltage i.e. about 1.5 volts.

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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.

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