Hmm, I'm getting to the point I'm going to give up on this now. I've spent too much time chasing my tail and I'm just not smart enough to figure it out.
I can get it to respond from 20 MHz up to 3.2 GHz without any input bias and it operates fine (if a bit deaf compared to the HP design, as per my previous messages), but then it has that free-running thing with no input signal.
If I use any sort of bias on the input (22K bias in the following example, the internal resistance from the input pins to Vcc is 7.5K) the random counts stop but the maximum frequency the prescaler operates to is only 2.4-ish GHz (minimum is still less than 100 MHz, so that's fine), BUT it seems there is some weird behaviour from the prescaler chip.
At a number of frequency ranges (shown below) it outputs roughly double the frequency that it should.... (changing the amount of bias just shifts the problematic frequencies up or down)
190 MHz - 195 MHz
224 MHz - 240 MHz
275 MHz - 305 MHz
350 MHz - 415 MHz
450 MHz - 495 MHz
I just don't know enough to figure this stuff out, so I'm quickly coming to the point of not continuing to waste time and dropping this project.
Jared Cabot