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John Weatherlv K1ZYG

The Dummy Loader

Did you ever wonder whether your RF was actually getting to your antenna or merely heating up the shack? lie Dummy Loader is a gild gel which indicates to dummys like me that the RF is in fact where it should be* Remembering that commercial transmitters use a sampling current for this purpose I figured I better have one, but RF Ammeters are expensive and there is an easy way to do essentially the same thing.

Take a small metal box about 4"x2"x2" and remove its cover„ In each end of the box install a coaxial connector of the type suitable for the transmission line being used. Between the center contacts of the connectors solder a length of bare #12 copper wire. Now find a pilot lamp (#47) and solder a pair of 2"

leads to it. One of these two leads is now soldered to the center contact of either of the connectors. Next connect the gadget into the transmission line on the output side of the antenna change over relay and connect the leed line to the other end of the gadget. Make certain at tliis point that the coaxial connectors are making good electrical contact with the box.

Apply power to the rig in the normal manner. At resonance lightly touch the free lead from the bulb to the #12 wire at a point about one inch from the soldered connection of the bulb. At this point observe that the lamp barely glows. (If not, turn out the lights in the shack or slide the loose contact along the #12 wire until a small glow is seen*) Retime the rig for maximum bulb brilliance. CAUTION: If you get tuo much brilliance the lamp will not last and power will be lost. When you have found the right spot TURN OFF THE TRANSMITTER and solder the connection to the copper wire.






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