Differences

This shows you the differences between two versions of the page.

--- packet:transceivers_144pk [2025/07/08 09:35] – g7taj
+++ packet:transceivers_144pk [2025/07/08 12:33] (current) – g7taj
@@ Line 21: / Line 21: @@
 {{:packet:switch_hl.jpg?400|}}
-Once in my hands ( a 400mile round trip back to my old QTH location, having just moved, which is coincidentally where Nick lives and I just happened to be there to visit family) and with all this information, it quickly lead me to work out that the binary counter driving the EPROM address lines and driving the synthesiser to setup the frequencies. What I didn’t know, is how.
+Once in my hands ( a 400mile round trip back to my old QTH location, having just moved, which is coincidentally where Nick lives and I just happened to be there to visit family) and with all this information, it quickly lead me to work out that it was the binary counter driving the EPROM address lines and driving the synthesiser to setup the frequencies. What I didn’t know, is how.
 I removed the EPROM and dumped it and noticed some very repeated patterns.
@@ Line 35: / Line 35: @@
   * The EPROM was clocked via the RC NOR gate oscillator
   * This oscillator could be stopped by D7 of the EPROM going HIGH
+  * D4 - D6 were used to send the DATA, CLOCK and ENABLE signals to the NJ88c22
   * The reset circuit was triggered each time the channel switch position was changed, which would start the counter again from zero