-
The original punchcards had a numbered square that you peeled off of the top surface of the card to reveal a punched hole under that square.
After some very careful measurements of old (used) punchcards and a lot of trial and error using CorelDraw vector graphics to lay out a template with the punch holes perfectly positioned, I can now reproduce them quite easily. They need to be printed on at least 40lb card stock paper or heavier if the printer will take it. I have also printed them on sticky labels and affixed them to heavy card stock and trimmed them to size. There is an optical reader inside the scanner that uses a pretty strong light source, so the material used must be dense enough to block all light passing through and around the edges of the card except at the precise location of the punched hole. I use a 1/8 inch paper punch to punch out the appropriate holes.
There was a 94 page programming book (≈100 frequencies per page) that came with the scanner that showed the binary code for which holes to punch for a given frequency. The book also gives a formula to follow for frequencies not listed. Line 12 on the card in the pic is punched for NOAA @ 162.475. Punch code is 0010101100011000 (1=punch, 0=no punch).
The last 3 positions on each line (14 15 16) told the scanner which of the available 5 bands to use :
100 - For 30.000 - 50.000 MHz
000 - For 150.000 - 170.000 MHz
001 - For 450.000 - 469.995 MHz
101 - For 470.000 - 489.995 MHz
011 - For 490.000 - 510.000 MHz
View attachment 117648
