"Tri-Mode-Keyer" - by WA7RSO
This "Tri-Mode-Keyer" was originally designed and constructed about or before 1972-1973 by myself WA7RSO.
*. I originally first "Breadboarded" my design to test the design concepts, then the circuit boards were made manually,
*. - by laying out each individual trace with drafting tape on a transparency above a grid lined paper base.
*. Negatives were created with Orthomatic Film for high contrast to expose the photo-resist-coated PC boards later.
*. Both sides of each circuit board was accomplished this way, and blank copper-coated fiberglass boards were cleaned,
*. - and treated with "Negative Photo Resist", then exposed to UV light for an appropriate amount of time to activate the Resist.
*. Then immersed in Tri-Chlor to to remove the unwanted Resist, and then on to the acid bath to remove the copper between the traces,
*. - leaving the copper traces for components.
*. Holes were manually drilled for through-hole components, which were then added and soldered in place (or socketed).
*. Standard TTL chips that became availble at that time were incorporated (they were quite new at that time).
*. After all parts soldered and the circuit tested, both sides of the boards were spray coated (except for the socket tabs).
*. Now in the process to reduplicate the original, and also with SMA devices, and also to incorporate various programable CPU's and LCD's.
*. These new ones will be known as "Multi-Mode-Keyers", with more personalities than the "Tri-Mode" had.
Keyer.html - SfE-DCS, ddf - WA7RSO - 05/21/2020