22 Mar
2007
22 Mar
'07
9:33 a.m.
Tyler
Usually, an RF voltage is specified as potential difference (PD), i.e. the voltage when connected to a 50 ohm load.
To convert uV to dBm :-
i) work out the power in Watts :- P=V^2/R so 25uV equates to 12.5pW or 0.0000000000125W.
ii) Multiply by 1000 to give the answer in mW; i.e. 0.0000000125mW.
iii) Take the logarithm and multiply by 10 to give -79dBm.
However, I'm not sure where 12.5uV comes from - a typical VHF receiver needs about 0.25uV or better - that's -119dBm; if your radio really needs 25uV then there is something seriously wrong.
regards
Grant G8UBN