There have been lots of articles regarding the improvement of the Heathkit IG-18, but none of them have ever offered a complete kit to make these modifications for   the DIY'er.  We are now offering a complete kit to upgrade the Heathkit IG-18 based on the many articles covering the IG-18.  This same upgrade can be performed on the IG-5218, SG-18,   and the SG-5218.
 
 This kit is available in two formats; one complete kit including the parts that need to be changed in the original IG-18, and a supplemental 'meter buffer' only kit for   those that have already made the basic changes to the Heathkit IG-18.  It comes with a complete step-by-step instruction manual for making the changes.
 
 We have discovered that a very few of the last IG-5218's utilized a meter that was manufactured in Japan.  This meter, while having the same electrical specifications as the   earlier meters, has a smaller physical spacing between the meter terminals.  For this reason, we have paid the additional expense to have new PC boards manufactured that will   fit both styles of meters.  We will constantly strive to improve our products even if it means throwing away perfectly good PC boards.
 
 THIS KIT IS FOR THE METER BUFFER BOARD ONLY.  This assumes that you have already made the easy changes to your IG-18 but either stopped short of adding the meter buffer   circuit, or like many others, implemented the additional circuitry on some kind of prototyping board.  This kit is intended to replace or add that meter buffer   circuit to your IG-18 and does not include the other components necessary to modify the existing boards in the IG-18.  The meter buffer is a crucial part of improving the THD   specification of the IG-18.  The non-linear loading of the analog output can create additional harmonic components due to the non-linearity of the diodes used to drive the meter.    By adding an additional transistor to increase the impedance of the meter driver and to isolate the rectifier diodes for the meter circuit, you remove this effect from the analog   signal path.
 
   This kit provides the necessary parts and PC Board to add the following:
 
 * Meter Buffer ONLY