Re: Power meter accuracy

John Lonigro

Cecil has probably given you the best advice.  However, I suspect you'll then have 3 power values and will begin to wonder about the accuracy of the RF probe.  Unless there is a systemic error involved, you can either average all three readings or simply throw out the high and low ones.  Or if you are really lucky and two of the readings are close to each other, throw out the third one, average the two, and call it good. 

I would suggest you buy the highly accurate KD1JV power and SWR meter, but I see that kit is retired (as am I).

Whatever the final result, that radio would be legal in the upcoming Second Sunday Sprint - official announcement coming shortly.

John AA0VE

On 02/04/2014 06:30 PM, Cecil Bayona wrote:

With a RF Probe measure the voltage across the dummy load, Ohms law
aught to tell you the power knowing the resistance and the voltage
across it. The only other thing you need to know is if your RF probe
measures Peak or RMS voltage, a cheap RF probe usually reads peak. If
peak you will need to convert it to RMS voltage before calculating the power.

That will verify which meter is closer.

At 06:11 PM 2/4/2014, you wrote:
>I did a bit of "domestic archaeology" in the attic this afternoon and
>found a long-forgotten Autek Research WM1 SWR/PWR meter. Managed to even
>find the matching wall-wart !! Put it in-line with the TenTec Argo 556
>and noted a difference in power reading between the Argo and WM1. The
>meter in the Argo shows 4 watts (dead center between the "3" and "5"
>points on the front panel meter) and the WM1 shows exactly 3 watts on
>the 0-20 scale.
>So, which one is closer to the truth? In the big picture, it doesn't
>really matter but I'm enough of a radio nerd to want to know closer than
>"3-4 watts". Is there a way to determine which reading is accurate? Can
>the WM1 meter cause that much power "loss"? I do not have any test
>equipment here so it may be a moot point. Your comments welcome. Thanks
>in advance.
>Bruce AA5CO
>4SQRP #664
>SKCC #10643T

Cecil - k5nwa
< > < >

Never take life seriously. Nobody gets out alive anyway.

Join to automatically receive all group messages.