Gamal says it all. It was impossible to keep the Decca coils tuned
accurately and maintain phase constancy without the copper screening. Even
then there had to be an automatic re-tuning device for when nearby
lightning strikes made the coils jump. It was driven by a small electric
motor and a belt/pulley arrangement that moved a little subsidiary coil
back and forth a few inches. Occasionally there was a direct lightning
strike on the antenna usually resulting in the belt jumping off the
pulleys and a panic callout for the duty engineer.
And for Bob, VE7BS - no, there was nothing in the hut except the loading
coils - it was only about 5 x 5 metres.
Walter G3JKV.
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