On Thu, Dec 27, 2012 at 6:45 PM, Tom Harris <celephi...@gmail.com> wrote:
> Watch out for Silicon Chip designs, they have a habit of not making the > source code available, which you only find out at the end of the project. I > suppose that it is to allow the author to make a few extra $$ selling > programmed micros. They had a nice 3 phase inverter design a year ago that > had this problem, I wrote to the author promising not to distribute the > source, I just wanted to read it, but didn't even get the courtesy of an > answer. > > I suspect that this counter is like the inverter, an oldish design that is > not worth building as you can get the same for half the cost out of China. > What makes it worthwhile is getting the hardware & the source code, so that > you can tinker with it. > I have a 2.7GHz counter out of China and cannot recommend it. If I feed it 10 MHz from a OCXO that is within 1Hz (as checked on my 5335A with high stability timebase), the counter will read fine for a while, then the reading will start drifting upwards and become unstable. I forget how high the reading drifts, hundreds of Hz at least. It will count to at least 2.7GHz, but I cannot trust it. It also has a 13 MHz output on the back. I looked at it on my TDS210 digital scope and there is a glitch on the leading edge of the waveform! It clearly goes up, returns to zero then finally goes back up for the rest of half a period. Whether this glitch affects the gating, I don't know. It's possible it is generated in whatever circuit buffers the clock for the output. Orin. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.