Heatkit IG 18 schematics please!

Tony · 28th May 2004, 11:35 PM

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 · 29th May 2004, 03:29 AM

Here you are J2,

This was a first page find with Google.

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

Tony · 29th May 2004, 04:54 AM

thank you very much....

richiem · 18th September 2010, 05:43 AM

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 · 18th September 2010, 04:19 PM

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

Heath IG-18 IG-5218

Tony · 18th September 2010, 08:18 PM

thanks a lot richiem....

29th May 2004, 03:29 AM	#2
roddyama diyAudio Moderator Emeritus Join Date: Jan 2002 Location: Michigan	Here you are J2, This was a first page find with Google. I built the IG 1272 (sinewave, push button) that I still use __________________ Rodd Yamashita

29th May 2004, 04:54 AM	#3
Tony diyAudio Moderator Join Date: May 2003 Location: Palatiw, Pasig City	thank you very much.... __________________ http://www.elab.ph/forum/index.php?topic=32688.0

18th September 2010, 04:19 PM	#5
Speedskater diyAudio Member Join Date: Sep 2002 Location: Lakewood, Ohio	We also have another active thread on the IG-18: Heath IG-18 IG-5218 __________________ Kevin

18th September 2010, 08:18 PM	#6
Tony diyAudio Moderator Join Date: May 2003 Location: Palatiw, Pasig City	thanks a lot richiem.... __________________ http://www.elab.ph/forum/index.php?topic=32688.0

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18th September 2010, 05:43 AM	#4
richiem diyAudio Member Join Date: Sep 2010 Location: Grapeview, WA	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.

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