. QST . and To,the kejer bias transformer. The balance of theheaters are supplied from a replacement-typepower transformer, rated at 750 volts, center-tapped, and volts at amperes. It will be noticed that no power switches appearon the transmitter proper. AH switching is done ata central control panel, located beneath the VPOtuning unit. As the schematic of Fig. 2 shows, 115volts is brought into an automobile ignitionswitch. Si, which allows the entire station to beshut off with a key. Since the key is carried in theauthors pocket, there is little likeUhood that thejunior ops will
. QST . and To,the kejer bias transformer. The balance of theheaters are supplied from a replacement-typepower transformer, rated at 750 volts, center-tapped, and volts at amperes. It will be noticed that no power switches appearon the transmitter proper. AH switching is done ata central control panel, located beneath the VPOtuning unit. As the schematic of Fig. 2 shows, 115volts is brought into an automobile ignitionswitch. Si, which allows the entire station to beshut off with a key. Since the key is carried in theauthors pocket, there is little likeUhood that thejunior ops will get their little fingers across thehigh voltage. The switching is arranged so that itis necessary for the exciter, final heaters and high- TABLE 1 Bandpass Coup er Data Coil Band Turns Wire Spacing B ct W No. L3 80 44 30 enam. M L* 80 37 30 enam. L5 40 21 30 enam. 7/16 L6 40 16 26 enam. U 20 15 24 tinned 9/16 3012 L8 20 10 24 tinned 3012 U* 15 9 24 tinned M 3012 LIS 6 24 tinned 3012 October 1955 17. Bottom view of the main chassis showing the grouping of the handpass couplers around the handswitcli in tlieupper left-hand corner. Rz, the bias-adjusting potentiometer for the switch circuit, is to the left of the grid-current milliammeter, top center. The 0B2 in the 4-65A screen circuit is mounted on a bracket below the and bias transformers are to the right. All power wiring is done with shielded wire. voltage-rectifier heaters to be turned on beforethe power can be apphed to the plate transformer. The switch, S5, a toggle, is the usualspotting switch, which grounds the key leadand opens the primarj circuit of the plate trans-former. The power-control panel is made from two7 X 9 X 2-inch aluminum chassis, bolted to-gether with their bottoms facing, with most ofthe front skirts cut away to receive an aluminumpanel. The VFO tuned-circuit is mounted onthis with shock mounts. Tuning Up After all wiling is checked, the oscillator tubeand cathode
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
