In order to proceed in getting new plastic dials made, that will not discolor, I need to borrow a dial from someone to use as a prototype; it doesn¡¯t have to be glass-clear as normal. ?It can be discolored, but all the printing needs to be present and undistorted. ?A little discussion about the mysterious darkening of some dials offers a good hypothesis about what is going on here. ?The normally clear plastic called Lexan (TM), a polycarbonate with production beginning in 1960, did (and still can) discolor; as most know, these radios are over 55 years old. ?¡°After 1970, the brownish polycarbonate tint was improved to glass clear.¡± ?On the other hand, acrylic often called Plexiglass (TM) will not discolor over time. ?As a reference, safety lenses and most all eyewear lenses are made of polycarbonate plastic because of its durability. ?So, this offers a plausible explanation why some dials are clear with no problems and others are this brownish color. ?Apparently the manufacturer of the dial used Lexan when the supply of acrylic ran short, temporarily, or perhaps began using Lexan altogether during the 60¡¯s in lieu of acrylic.
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If someone can allow me to borrow a spare B-line dial, please let me know. ?I will do everything possible to keep it in the present condition.
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Thank you.
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73, Michael Smith, N4KZO
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