I am currently playing with tuners... Specifically link coupled... And
I have been making my own condensers... Part of the exercise includes
efficiency 'that' word again of power transfer, more specifically
tank coil losses... I had been using my fingers as my calibrated
temperature differential meter but I have gotten the tuners engineered
to the point where there are not enough differences to tell by feel...
So I purchased an Infrared measurement gun...

fascinating little instrument - did you know that on a clear day with
the air temperature +12.1 F and zero wind, that a 5 foot diameter
black rubber tractor tire facing the clear sky to the North can have a
surface temp of -2.6 to -3.0 F? I didn't but that is what I found...
OK, I digress again

So, I have been running power soak measurements of the tuner components
with the power source remaining energized during measurements - the
nice part of a non contact instrument... The measurements turned up
surprising results to me...
The continuous power level was 680 watts input to the tuner box at 3508
kc ( two Bird meters, uncalibrated and the power averaged / 670 and 690
W. respectively)... The power soak time was ten minutes total... The
outside air temperature was +12.1 F throughout the measurement period -
mid day... The tuner components were +12.8 at the start (- + 0.2 F)...
The tuner parts are in a plastic waste bin with the top on, except
during measurements, to control air currents... The box sits about 4
feet away from the wall of a large building and shaded from direct
sunlight weak sun at the time of measurement...
The coil is ~4" diameter and consists of 20.5 feet (22 uH) of #10
enameled wire wound on a paper mailing tube, and glued down with
epoxy.. The link coil is the same wire (2.2 uH) wound on PVC tubing
and slid inside of the tank coil tube - it was not available for
temperature measurement, a finger slid inside of the PVC tube did not
detect any temperature rise power off!... The tank condensers are
aluminum and are ~24 square inches in area per plate (a pair of caps in
a series tank configuration)...
At 5 and 10 minutes the top was popped and the surface temperature of
the tank coil and condensers were measured - taking about 30 seconds -
and the top replaced... The results for both times were within a few
tenths of a degree...
The coil was found to be +12.9 to +13.1 F and the condenser plates were
+31.5 to +32.3 F... A result which sent me away mumbling to myself...
Not what I expected...
This is consistent with an earlier test in which the tuner was powered
for 10 minutes at 1800 watts with the exciter sending dahs at 20 wpm (
typical contesting environment)... The components were finger measured
power off and the coil felt to be barely above the starting
temperature and the plates to be just a bit warmer than the starting
temperature, which prompted the purchase of the infrared gun because it
couldn't possibly be right - we all know that condensers are 100%
efficient and coils are lossy - right?...

denny / k8do