Jason continued to develop his 7400 contest entry the 80M direct conversion receiver, here is an update:
Finally, I addressed the lack of knowledge of what frequency is being tuned by adding a frequency counter. It is based on the XC9572XL breakout board from Ian and company. Coding the counter was a good learning experience for me as I learned how to squeeze more and more out of the limited logic available on the CPLD until I got it to do what I wanted. I tested the counter up to 100MHz and found that it tracked accurately to over 90MHz and then it started missing counts by the time it got to the mid-nineties. Still impressive given that the timing analyzer predicted a maximum of around 71MHz. Since I multiplexed LEDs (vintage HP calculator LEDs in the picture), I found that the display didn’t look good when I gated the counter at 100Hz as the update rate was too slow. So I dropped to a 5 digit display (99.999MHz) and a gate frequency of 1kHz which allows me to update each of the LEDs 200 times per second.
Via the forum.