Morrey's Super Oscillator Heathkit IG-18 Modification

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mediatechnology
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Morrey's Super Oscillator Heathkit IG-18 Modification

Post by mediatechnology » Sat Jul 12, 2008 10:51 am

I have a Heath IG-18 "low distortion" oscillator I modified a number of years ago to become Morrey's Super Oscillator based on a TAA 4/75 article. The IG-18 (or IG-5218) can still be obtained on eBay on occasion and I use mine quite often.

Image
Image Courtesy of The Audio Amatuer Issue 4/75

The large-format file is here:
https://www.ka-electronics.com/Images/j ... llator.JPG (2.3 MB)

A pdf of the article here:
https://www.ka-electronics.com/Images/p ... A_4-75.pdf (5.8 MB)
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

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mediatechnology
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IG-18 Modification: What is the Lamp Part Number?

Post by mediatechnology » Tue Sep 20, 2011 2:19 pm

I've always wondered what the industry part number was for the lamp, L1. I recently found this text online at DIY Audio: http://www.diyaudio.com/forums/equipmen ... 8-a-3.html
The lamp itself is marked SYL 90V. I was able to cross-ref to a Sylvania 90MB, which is a T2 bayonet-mount bulb with the right envelope shape, 90 volts at 30mA, giving a hot resistance of 3k ohms. I pulled one lead of the lamp and its cold resistance is around 280 ohms. I say around because even the small current from the ohmmeter raised it to 290 ohms while I was measuring. This all seems to be in the right ballpark to me, even though the cold R seems low.
I think the 90MB is a replacement based on the following information.

This is what the original looks like with wire leads:

Image
Image Courtesy of Surplus Sales

The Chicago Miniature Catalog shows that the wire lead, slide base and bayonet base have identical electrical characteristics. Unfortunately they only made 60 or 120V lamps, not 90V.

Image

It would appear that the 90V version had a part number 90PS. Fortunately the 90MB is still made and available:

Image

The original lamp wire lead lamp was either custom-ordered or long-discontinued. I suspect that 90V lamps were used in telecommunications.

Allied Electronics carries the 90MB: http://www.alliedelec.com/search/produc ... KU=9379720

Hope this helps anyone that needs a lamp for their Heathkit IG-18. I love mine.

I'll be ordering some 90MB lamps from Allied and will provide feedback.
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

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mediatechnology
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Re: Morrey's Super Oscillator IG-18 Modification

Post by mediatechnology » Tue Sep 20, 2011 3:22 pm

Dick Moore has this page on lamps for oscillators.

http://www.moorepage.net/Lamps.html
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

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