Rich,
I believe the ARRL test was in fact reported in QST. They were lab testing a
number of tuners.
Len
At 02:26 AM 3/31/99 -0800, Rich Measures wrote:
>
>
>
>>
>>Jim says:
>>
>>> >I am pondering ways of actually measuring the efficiencies of these
>>> tuners, >but am not sure how to proceed.
>>>
>>>
>>measure the load impedance, measure the current with a thermo ammeter.
>>Calibrate the thermoammeter with DC: measure its RF resistance (not easy!)
>>at the frequency in question, ,measure the DC resistance and calculate a
>>correction factor. Taking into account the inaccuracies, and the fact that
>>the tuner should hopefully be 98% efficient or better, you may well find
>>that the measurements tell you that the tuner is really an amplifier!
>>
>>Seriously, I think the best way to get an idea of tuner efficiency is
>>temperature rise after ten minutes of key down at full power. And if the
>>Delrin catches fire before then, you know it ain't that efficient..........
>>
>Unsubstantiated rumour has it that in the ARRL lab test of the MFJ "3kW"
>tuner Delrin ignition occurred at c. 30% of the mfg.-rated power level.
>>
>- later, Peter
>
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
>
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