Re: Procedure to measure rf watts

Jim Potter
 

If you use a directional coupler you need to be sure that it is calibrated properly. Unless you have a fully calibrated 50 Ohm system your measurement is nothing more than a WAG (Wild A$$ Guess). The higher the frequency the more complicated it is to get accurate measurements.


At 07:54 PM 5/22/2019, Jim Ford wrote:
Definitely use a directional coupler or an attenuator.I assume that the flow-through wattmeters like those made by Bird have couplers inside those plug-in modules.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone --------
Original message --------From: sdturne@q.com Date: 5/22/19 6:25 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Procedure to measure rf watts On Wed, May 22, 2019 at 04:00 PM, Randy.AB9GO wrote:>> Hello everyone,> > I have a need to check the calibration on some low power watt meters (10 watts> or less, 21 megahertz or less) and was wondering if anybody had a favorite> procedure using their scope to measure peak-to-peak rf voltage without letting> out the magic smoke. My thought is to use a t connector, hook one side to the> transmitter, one side to a dummy load and then the center connector straight> to the 10X oscilloscope probe. Any other precautions I should take?> > Thank you,> Randy.>I will say above anything else, 10W is way too much power to be putting into most test equipment, especially spectrum analyzers. You *will* burn up something in the frontend and then you'll be sad. You want something like an RF sampling tee that will couple a much smaller version of your TX signal into your instrument.Sean
James M. Potter, PhD, President
JP Accelerator Works, Inc.
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