Re: Procedure to measure rf watts

Chuck Harris <cfharris@...>

The venerable bird wattmeter is really quite awful in terms of
accuracy. At its rated best, it is +/- 5% of full scale.

So, if you are using a 10W slug, its accuracy band is +/- 0.5W.
Ok, if you are measuring 10 W, but it gives you a 50% uncertainty
if you are measuring 1W.... 20% if you are measuring 5W.

Your scope can do much better than that.

-Chuck Harris

Dennis Tillman W7PF wrote:

Hi Randy,
How about a Bird Wattmeter. They are the first thing a ham thinks of when they need to measure RF power.
Dennis Tillman W7PF

On Wednesday, May 22, 2019, 4:01:03 PM PDT, 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,

Join to automatically receive all group messages.