The Preamplifiers-Integrators circuit diagram. Note that the EW preamplifier-integrator is identical to the NS preamplifier-integrator that is shown completely in the top center. All resistors shown with three significant figures are 1%, 1/4-watt carbon film. All other resistors are 5%, 1/4-watt carbon film. Polarized capacitors are 35 V tantalum. C1 to C4 are 50 V polyester film capacitors (Panasonic B-Series, Digi-Key), matched within 1%. Capacitors in picofarad units can be either zero-temperature-coefficient ceramic (Panasonic Monolithic Type COG) or dipped-silver mica; the remainder are polyester film. C5 determines the E-field gain when the attenuator relay is closed, 200pF to 2700pF. Similarly, C6 sets the normal gain, 100pF to 1600pF. See text. Trim pots, P1 and P2, are 6-mm cermet (Panasonic Series 36C). Relay is a 12 V SPST reed relay (Radio Shack 275-233). Components marked with # make up the first pole of the 5-pole low-pass filters. See text under Low Pass Filter Construction.   Note Spring 2001: Q7 was originally specified as an RCA 40673 but is no longer available. The NTE222 is a replacement item with identical characteristics.