Have just finished assembling one of these,the 2003 model Silicon Chip frequency counter. Follow link for complete article with circuit diagram.
Among other things, it is intended for use as a readout on a signal generator, an archaic solid state RCA job from about 1969. The counter is fine up to about 10MHz but then it runs out of sensitivity and will no longer read the output of the signal generator. Problem does not seem to be with the signal generator. Looking at the waveform on a 'scope, it is putting out around 50mV p-p all the way up to20Mhz and there is no drop off in output at the point where frequency counter ceases to read. Designer of frequency counter says "Input sensitivity: Typically less than 20mV rms from 1Hz to 100kHz rising to 50mV at 20MHz and 85mV at 50MHz"
I've done some Googling for "frequency counter preamp" and similar search terms but haven't seen anything very useful.
Any ideas for improving the front end of this counter for more sensitivity?
Current residents of my crap filter: soundhaspriority Robert Morein George Middius Phil Allison Brian Goldsmith