( ) Using the Meter Adjust control on the new Meter Board, adjust the reading of the meter to indicate 1 Volt RMS ( ) This completes the IM-18 Distortion Mod THD Measurement We are currently working on a small PC board that will allow you to determine the approximate THD measurement of your newly modified IG-18. This board should be available in a couple of months. Please watch our listings on eBay for when these will become available. Appendix 1 IG-18 Component Replacements C1 1000 µF 63 VDC Electrolytic Capacitor – C2 1000 µF 63 VDC Electrolytic Capacitor – C3 470 µF 63 VDC Electrolytic Capacitor – R1 56k (Green, Blue, Orange) ½ Watt Resistor (Larger than the others) – C5 100 µF 50 VDC Electrolytic Capacitor – Meter Board Components D1 D3 1N270 Germanium Diode – R1 Meter Control 10k Potentiometer – R2 (Brown, Black, Brown) ¼ Watt Resistor – 100Ω R3 R4 100K (Brown, Black, Yellow) ¼ Watt Resistor – R5, R6, R8 10K (Brown, Black, Orange) ¼ Watt Resistor R7 (Green, Blue, Red) ¼ Watt Resistor (*Optional See Text) – 5600Ω Q9 417-801 MPSA20 Transistor – C1 10 µF Electrolytic Capacitor – C2 C3 100 µF Electrolytic Capacitor – C4 220 µF Electrolytic Capacitor – Contact Us Don Peterson Data Professionals
( ) Using the Meter Adjust control on the new Meter Board, adjust the reading of the meter to indicate 1 Volt RMS ( ) This completes the IM-18 Distortion Mod THD Measurement We are currently working on a small PC board that will allow you to determine the approximate THD measurement of your newly modified IG-18. This board should be available in a couple of months. Please watch our listings on eBay for when these will become available. Appendix 1 IG-18 Component Replacements C1 – 1000 µF 63 VDC Electrolytic Capacitor C2 – 1000 µF 63 VDC Electrolytic Capacitor C3 – 470 µF 63 VDC Electrolytic Capacitor R1 – 56k (Green, Blue, Orange) ½ Watt Resistor (Larger than the others) C5 – 100 µF 50 VDC Electrolytic Capacitor Meter Board Components D1 – D3 1N270 Germanium Diode R1 – Meter Control 10k Potentiometer R2 – 100Ω (Brown, Black, Brown) ¼ Watt Resistor R3 – R4 100K (Brown, Black, Yellow) ¼ Watt Resistor R5, R6, R8 10K (Brown, Black, Orange) ¼ Watt Resistor R7 – 5600Ω (Green, Blue, Red) ¼ Watt Resistor (*Optional See Text) Q9 – 417-801 MPSA20 Transistor C1 – 10 µF Electrolytic Capacitor C2 – C3 100 µF Electrolytic Capacitor C4 – 220 µF Electrolytic Capacitor Contact Us Don Peterson Data Professionals
Heathkit%20IG-18%20Mod%20Manual%20Rev%202.docx