‰ NOW 30 WPM ‰ TEXT IS FROM JULY 2014 QST PAGE 34‰ LINEAR IN TERMS OF DB PER VOLT. BUFFERING THIS SIGNAL WITH A HIGH IMPEDANCE OPERATIONAL AMPLIFIER GAVE ME A METER DRIVER THAT IS LINEAR AND INEXPENSIVE TO CONSTRUCT. WHILE I WAS AT IT, I TOOK THE OPPORTUNITY TO IMPROVE ON SOME OTHER LESS DESIRABLE S METER CHARACTERISTICS SUCH AS ZERO DRIFT, AND JAMMING AGAINST THE STOPS WHEN CHANGING MODES. FIGURE 1 SHOWS HOW THE NEW METER DRIVER CIRCUIT INTEGRATES INTO A 75S 3B RECEIVER. COLLINS COLLECTORS WILL BE RELIEVED TO HEAR THAT INSTALLATION OF THE CIRCUIT BOARD REQUIRES NO WIRE CUTTING THE BOARD MOUNTS DIRECTLY ON THE S METERS TERMINALS AND THE ORIGINAL METER LEADS ARE PARKED OUT OF THE WAY ON STORAGE BOLTS AT THE BOTTOM OF THE BOARD. POWER FOR THE BOARD COMES FROM THE S METERS PILOT LAMP AND THE AGC VOLTAGE IS AVAILABLE FROM THE WIPER ARM OF AN ADJACENT ROTARY SWITCH. CIRCUIT DESCRIPTION THE CIRCUIT DEVELOPED FOR THE NEW METER DRIVER IS SHOWN IN FIGURE 2. NO VOLTAGE GAIN IS NECESSARY. THE CIRCUIT IS BASICALLY A VERY HIGH INPUT IMPEDANCE VOLTAGE FOLLOWER THAT DIRECTLY MEASURES THE AGC VOLTAGE AND USES IT TO DRIVE THE S METER. POWER IS SUPPLIED TO THE CIRCUIT THROUGH THE V AC AND GND INPUTS ‰ END OF 30 WPM TEXT ‰ QST DE W1AW ƒ