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Shielding dummy loads

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While checking a new rig I connected a dummy load (a 25 watt lamp) to the transmitter. During the checks I heard an out of town station calling CQ. I was still using the dummy antenna on the transmitter but since I was tuned up on his frequency I gave him a call just for fun. Not only did I make the contact but I also received a good report!

A later check with a field-strength meter indicated an extremely strong r.f. field around the lamp. I applied several coats of conductive paint (Television tube coat, General Cement No. 49-2) to the glass envelope around the lamp, leaving a small ¼ inch circle to allow observation of lamp brilliance. After this coating, the field-strength meter gave only a slight reading a few inches from the dummy load. Now, the lamp makes a good dummy antenna.

Harrison A. G. Stone, K2LIF.