Decided that in fairness to the THD, s/n thread the IG should be I modified this IG a long time ago — looks like it’s in need of modding. This same upgrade can be performed on the IG, SG-. 18, and incorporated into your kit by Heathkit, depending on when your particular model was sold. Download HEATHKIT IG SINE-SQUARE AUDIO GENERATOR SM service manual & repair info for electronics experts.
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This project takes the popular Heathkit IG and audio generator to a whole new level of performance, replacing the main board with a design based-on the HPA. The write-up is in the form of what I call construction notes, which is brief. Oscillator board pictorial layout. Oscillator board bottom view. New range switch with cap board heathki.
PCB Created for the Project! After doing the layout, he fabricated his own, single- sided Ig-52188 and successfully built the working generator. Performance results seem at least as good as the ones we obtained.
His project, with the PCB, is shown below. The PCB layout, as seen in Eagle is at left. Click on it for higher resolution. Note that red topside traces are only to guide topside wiring. Also, everything shown outside of the terminal reference letters is just extra descriptive info, in a reference layer. For readers who want to fabricate the PCB, Larry provides the following tips edited and augmented:.
Click on the image at left, for a high resolution pdf file, showing the silk- screen and topside jumper wires. Click on the image at left, to download a small zip file, containing the files package for PCB fabrication.
Audio Generator IG-5218
The PCB files package includes:. The drd file is excellon drill data. Note that this layout is intended for a single sided board. The topside traces shown in the BRD file are only to guide topside jumper installation. They are not suitable for fabricating a topside copper layer on the PCB.
Dick has done extensive work on various approaches to enhancing the IG His write up on it is here. I must say that the distortion figures seem almost too good to be true under 0. However, his measurement methods, while indirect, certainly make sense. The Heathkit tuning network uses a It originally seemed likely that the higher ratio was responsible for the low distortion performance of the HP oscillator.
However, he reports measured distortion figures under 0. While I find this very surprising, Dick obviously has done a lot of excellent work on this, so I would hardly question his results. Maybe you know the feeling—so many toys, so little time: Sadly, Dick passed away in However, inhis wife Robin graciously allowed Tronola to preserve his website, Moorepagewhere you can find more information.
Posted by Shawn S.
Modifications: Heathkit IG Audio Generator
August 27, – I’ve used Osh Park but they won’t do single sided boards. Shame I don’t have the time or patience to figure out how to mod the file. I’d probably add plated through holes with tiny pads to the top layer as well. Any help would be appreciated. Posted by Steve L. September 22, – The main concern about the diode is its forward characteristics.
That’s because the IG meter scale is corrected for hathkit diode effects at low voltage. Heath’s part number for the diode was which is shown as a 1N in the cross reference table at d8apro. I looked at the NTE replacement but it’s not a very good characteristic match.
The diode I actually used which worked well came from Radio Shack more than ten years ago and was an unmarked Germanium, as I recall.
Shouldn’t matter a great deal though and the 1N34A looks like a good match for the forward spec. Ig-218 current is about 30mA on each rail and the positive rail rises to about 47mA with the square wave converter on.
Let us know how it goes. Will be happy to help if you have further questions. Do you have a part number for the germanium diode? Also, Being a project nut, I have several small footprint toroidal transformers on hand. What would be the ballpark specs that would work for this? I wish they would indicate that on the “obsolete” page. The schematic and the parts list in the construction notes have been updated to show the CDB as heathkitt.
Thank you hfathkit bringing this up!
September 21, – Mouser and Digi-key doesn’t seem to carry them. Remove the B and quite a few places have the 74C Any help would be greatly appreciated. October 25, – Hearty congratulations on completing the project! I hope that using your new IG gives you as much pleasure as using mine has given me. Before doing this project, I had gone through previous iterations of “greening” the critter, beginning way back in the seventies with an article from the Audio Amateur.
While those reduced distortion, they increased settling time and reduced stability. Now when I use it, I recall how it used to waver around the final level and change level across the bands. The way HP’s excellent circuit just locks right in on the level seems almost magical in comparison. Add your comments here The board is intended for single-sided, DIY fabrication.
As such, the topside traces are to guide topside hand wiring and the silkscreen was for guidance, rather than application to the board. While some silkscreen marks may overlap pads, PCB vendors typically mask out the silkscreen over the pads, anyway. The overall dimensions of the board are 5. Pot R54 1kohm is added, in series with R If the pot is used, reduce R51 to 2. Adjust the pot for minimum second harmonic distortion. The power supply seems quieter with two 10uF tantalum caps added, across C5 and C6.
It is a direct replacement, except that the compensation components are left out. Those would be C44,45,48, CR7,8, R27, Dick also left out C32,46 and R29, though he and Larry think that these last three might be useful. Eagle version-6 is required to open the.
Eagle generates errors if an error check is run on the board.
Audio Generator IG Equipment Heathkit Brand, Heath Co.;
After inspection approve all of them and it will be okay. It would be worthwhile during checkout to disconnect it at transformer end to see if it is adding anything, especially on the high value range resistances.
Normally, the leads will be positioned on the opposite side from the lamp —ed. For the square wave generator, the CDB was substituted for the equivalent 74C14B, since the other chip was handy. Other specifications were not tested but the chips have similar speed ratings. It was a pretty easy job and is accurate. Gerber files for PCB fabrication are provided below. If instead, you wish to generate your own output files from the. If you wish, you can view the Gerber files using the free application, GC-Prevue.
Note that it will show errors which are harmlessdue to the fact that informational parts of the layout extend past the Eagle zero-reference. That was needed to use free Eagle to create the board.
Heathkiit has kindly generated Gerber files to allow PCBs to be fabricated at commercial board vendors. However, those files have not at this point been used to make a board. Please proceed at your own risk. We would very much like to hear, your results, if you have boards made with the files —ed. PCB Files for Download Click on the image at left, for a high resolution pdf file, showing the silk- ig-52218 and topside jumper wires.
The PCB files package includes: Reader Comments Posted by Shawn S. Bottom view of the oscillator board wiring.