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![]() "Avery Comarow" wrote in message ... On Feb 13, 10:41 pm, "Richard Knoppow" wrote: At some time in the recent past there was a discussion in this or the antique radio group about coil dope. As a result I tried making some. ...What I did was to dissolve polyfoam shipping material in a mixture of MEK and xylol. I chose these two solvents because both were listed on the lable of some old commercial coil dope. Richard Knoppow Proportions, please? Mostly MEK. I added a little Xylol (AKA Xylene) because I thought I saw it listed in an MSDS for coil dope. However, the MSDS for the General Cement product lists only MEK although the thinner is Toluene. If I do it again I will use straight MEK. I added the styrofoam until the stuff got to what seems to be the right consistency, about like honey. Mine came out a sort of gray color rather than clear but the pictures of the General Cement Q-Dope also look gray. My styrofoam was scraps of shipping material from something I mail ordered. It is amazing how quickly it dissolves, at least at first. I used a small, wide-mouth, bottle I got years ago. I would test the cap of any container you plan to use with a little MEK to make sure it will not be attacked. MEK is a rather wide spectrum solvent which will dissolve latex and a number of other substances. I will make some measurements when I have a little time to see if my dope affects coil Q. Commercial dope has very little effect. MEK is available at any paint or hardware store and styrofoam abounds. One can use styrofoam cups but I think a sufficient supply can be found free. I tried making my own after working on an old Hewlett-Packard signal generator (606-A) where the high band coils must be fastened down with it after adjustment. I found none of my usual local suppliers had the stuff. I have since found that Action Electronics, in Anaheim CA carries it but that is a 30 mile drive from here. So, I decided to make my own. -- Richard Knoppow Los Angeles WB6KBL |
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