Re: K2 power out accurate? (UPDATE/CLARIFICATION)

Posted by Don Wilhelm-4 on Jan 11, 2012; 1:18pm
URL: http://elecraft.85.s1.nabble.com/K2-power-out-accurate-tp7174240p7176115.html

David,

That piece of information indicates to me that your wattmeter is not
accurate for power readings when the impedance is not 50 ohms.

You have the KAT2, and I presume you have calibrated it to agree with
your QRP Wattmeter when it is connected to a 50 ohm load.

The KAT2 does not change anything on the antenna side, it only creates a
low SWR on its input side so the K2 PA transistors are "happy" - there
will be no change of the antenna SWR (which is what the wattmeter is
reading).

With your report, I would hesitate to trust the reading of your QRP
Wattmeter when it is connected to something other than a 50 ohm
resistive load.

73,
Don W3FPR

On 1/10/2012 11:46 PM, David Dietrich wrote:

> Evening All,
>
> I neglected to mention this one piece of information with my issue on the K2/10.  The pinning of my Wattmeter happens when I have the K2 connected to my outside antenna in this order: K2 to Wattmeter to outside antenna.  This is after I do a tune and get a low SWR.  My K2 DOES have the KAT2 tuner installed.  My antenna is a simple G5RV Jr.  I originally said that I had it connected to a dummy load and that was happening.  Sorry about that.
>
> I did connect the K2 to my Wattmeter, and then to my Dummy Load,  and power output was within a Watt or so on different power settings.  So, that tells me the Wattmeter is calibrated within tolerances and the power out appears to be accurate.  I also verified this with my other HF radios, both kit AND commercially produced.
>
> Still, I wonder what would cause my Wattmeter to be pinned at 5W when transmitting into an actual antenna?
>
> The Wattmeter is the QRP Wattmeter from Oak Hills Research, and the 100 W dummy load is from them as well.
>

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