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Yes, QEX December 2002. The tank coil
was located about 30mm away from the perforated steel casing and when the Tx was
running at the 700W level the casing immediately above the coil reached
over 100deg. (the reast of the PA was quite cool). A sheet of soft
aluminium of > 1mm thickness interspersed between the coil and the casing
solved that problem, and the Q of teh tank rose a bit. The AL has to
have a thickness of a few skin depths to be worthwhile, so 0.5 to
1mm. Al foil is barely good enough at a few tens of microns
thickness, and might suggest why some people find lining an otherwise lossey
cabin with it to be not very effective.
Andy G4JNT
I think that was G4JNT's off-line TX
using circuit techniques from the Decca design. As I recall, When Andy
initially put the TX in a steel case, the casing around the tank coil got
very hot due to eddy current heating. The problem was overcome by placing
aluminium sheeting between the coil and the steel
casing.
That is correct. Andy published his
design in QEX.
73, Dick,
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