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RF sampler / demodulator for oscilloscope

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giboni:
 :)

 Looks easy to build. Am going to use a steel electric conduit box to put it in.

Apparently. For lets say 1KW+ on AM. I need to use larger resistors. What value and watts could they be ?

Best John

guitar_199:
Just to be sure, check the video.  That 690 K, should be 690 ohm.
It is not a danger to equipment... it affects the accuracy.
With 47K nominal over 690 ohm in parallel with the load of 50 ohms (the cap is negligible at almost any RF) you get  a voltage divider of 46.6/47046.6 which is almost exactly 1/1000 (.00099051 in fact) which is almost spot on -60 dB attenuation (60.08).
If you do it with 690K that 46.6 goes up to 49.99 which makes your voltage divider 49.99/47049.99 which works out to -59.47 dBm.

It isn't a huge difference but some users may value that.

According to my calculations, at 1000 Watts RF In the 47K would dissipate 1.06 watts.  So use a 2 or 3 watt piece for safety.
At 1500 watts I show 1.59 watts so , again, a 3 watt piece, maybe 5 watts and that should handle it.

For other fun,    15K instead of a 47K would be -50 dB attenuation (15K will dissipate .33W at 100W RF/ 2w at 600w RF/3.3w at 1000W RF)
     4.7K would be -40 dB (4.7K will dissipate .107w at 10w RF / 1.04w at 100w RF).

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