. QST . edconsiderably, and what is normally amilliammeter becomes a Mill be found to be a handy anduseful instrument to have around theshack. Once you have used it you willsee why it is called the Little Gem. resistance, Ri. If the signal being measured isvery strong, no external antenna will be necessaryfor full-scale deflection. When more sensitivityis needed, a short piece of stiff wire can be con-nected to the antenna binding post. If it is desired to check the quality of a phonesignal, it is only necessary to plug a pair of head-phones into the phone jack. The closed-ci
. QST . edconsiderably, and what is normally amilliammeter becomes a Mill be found to be a handy anduseful instrument to have around theshack. Once you have used it you willsee why it is called the Little Gem. resistance, Ri. If the signal being measured isvery strong, no external antenna will be necessaryfor full-scale deflection. When more sensitivityis needed, a short piece of stiff wire can be con-nected to the antenna binding post. If it is desired to check the quality of a phonesignal, it is only necessary to plug a pair of head-phones into the phone jack. The closed-circuitjack isolates the meter from the circuit and al-lows the amplified audio component of the recti-fied signal to be heard. When the instrument is to be used as a micro-ammeter, the transistor is switched from thediode rectifier circuit to polarized pin jacksmounted on the cabinet. The transistor continuesto operate as a current amplifier, and full-scaledeflection can be obtained with a very small cur-. The transistorized LittleGem with plug-in coils whichprovide coverage of all ama-teur bands, 160 through 6meters. The phone jack ismounted on the side of thecabinet and insulated by fiberwashers. 16 QST for 1N34A c, OFF /^?o ■K A-J,9+J,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
