At 11:41 PM 11/30/2009, Joseph Gray wrote...
We all have our various highly accurate frequency and perhaps time
references. Is there a relatively simple and inexpensive method of
making an accurate RF power level reference?
Joe Gray
KA5ZEC
Since you're a ham, I'll assume you're primarily concerned with the
simple case (50 ohm source impedance, sine wave, HF-VHF). Use an
o-scope to measure the p-p voltage across a precision 50 ohm load (I
use the Caddock thick film resistors available through Digikey, which
are 1%, with minimal inductance).
The power is then W=((Vpp/2)^2)/100
Not time-nuts precision, but good "bang for the buck," and you can get
better accuracy than a Bird wattmeter (which is only 5%), assuming you
have a decent scope. Without an o-scope, you can make a peak detector
and use a voltmeter, with some loss of low level accuracy.
You asked for "simple and inexpensive." For higher frequencies,
different impedances, non-sine waves, the other more expensive
solutions are needed.
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