Heatkit IG 18 schematics please!

[TonyTecson]

can anyone please send me schematics for this heatkit sine-square wave generator?

i lost the manual when we changed residence! this function gen is pushing years and still functional,

i would like to find out if any upgrades could be done. thanks

 

[roddyama]

Here you are J2,

This was a first page find with Google.

I built the IG 1272 (sinewave, push button) that I still use

 

[TonyTecson]

thank you very much....

 

[richiem]

Tony, see Heathkit Schematic Diagram Archive then scroll down to the SG-5218. The schematics are there. There are only three components that were changed in the SG-5218 from the IG-18 --
C5 from 0.68uF/25V to 100uF/35V
R3 from 4.7k to 56k
R11 from 150 to 130
I think that's it.

Then read Reg Williamson's mods, particularly the meter buffer amp -- that is crucial to best performance. Ignore the mod to make Q3 a darlington pair -- it didn't work and Reg retracted the suggestion. Also do not bypass R11 as he recommends -- that makes HF performance dicey.

Good luck.

 

[Speedskater]

We also have another active thread on the IG-18:

http://www.diyaudio.com/forums/equipment-tools/168718-heath-ig-18-ig-5218-a.html

 

[TonyTecson]

thanks a lot richiem....