User manual HARBACH ELECTRONICS PS-220

[. . . ] Lift the case up and remove it from the amplifier. Place the amplifier on the bench with the front panel facing you. You are now ready to proceed with the installation. [. . . ] Trim the lead to about 1/8" protruding. Slip the loop end of one of the parasitic choke/resistor assem blies over one of the plate cap screws with the coil up, followed by a #6 lock washer. Install this assembly on one of the plate caps with the assembly pointing toward the HV lug. Fish the free end of this assembly through the outer hole in the HV lug and trim the end to about 1/8". In a like manner, inst all the other parasitic choke/resistor assem bly onto the other plate cap, trimm ing the end to 1/8". Now solder the 3 wires going through the HV terminal of the plate choke. Turn the amplifier upside down with the front panel facing you. () () () () () () () () () () () 1 () Locate the (2) 1mH chokes going from the rear-most tube socket pin. Clean out the hole through which the chokes were removed. In place of these chokes, install a 27 resistor paralleled with one 820pF disc capacitor (1 resistor/capacitor pair for each choke). On the right hand tube socket, parallel the existing 200pF capacitor closest to the front panel with (1) 820pF disc capacitor. Leave all other 200pF capacitors in place. On the left hand tube socket, parallel the 200pF capacitor on the extrem e left with the remaining 820pF disc capacitor. Leave all other 200pF capacitors in place. Locate the 2-lug terminal strip just behind the filament choke (the input drive coax is connected here). Remove the capacitor going from this strip to the filament wires. Clean solder from the terminal strip w here you just rem oved the capacitor. [. . . ] Replace the perforated cover and top rear plate cover. Reinstall the 15 s heet m etal screws holding these pieces in place. DO NOT over tighten these screws, as it is fa irly easy to strip the screw threads in the aluminum underneath. [. . . ]