[Elecraft] Tuner efficiency question

[Bill Coleman]

On May 13, 2005, at 12:40 AM, John, KI6WX wrote:

> At high power, an inefficient tuner can generate significant  
> amounts of heat, which can destroy components.  A 1kW transmitter  
> into a 70% efficient tuner will generate 300 watts of heat in the  
> tuner.

This is why I tend to disbelieve tuner efficiency figures. From the  
QST tests, there seem to be a lot of tuners than have losses greater  
than 10% -- yet there is no evidence that any of these tuners heat up  
appreciably! At 1 kW, a 10% loss is 100 watts -- imagine how hot a  
tuner enclosure would get if you had a 100 watt light bulb inside it.

Even at 100 watts, 10% loss is 10 watts. That's still enough to  
induce a few degree change in a small enclosure.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901