02-04-2014, 04:53 PM
(02-04-2014, 04:36 PM)AlanBeckett Wrote: The Link to the Boonton Probes is interesting. I particularly liked the construction method using Copper Pipe - just my line, although I'd probably throw a bit of Turning in there.
Yes, I can see the reasoning to that. You have rough idea of the freq. whose amplitude you want to measure, but at the same time, you want to be sure that you're measuring the amplitude of that signal, and not have an erroneous measurement made on account of any unwanted signals and noise, etc. But any such tuning will have to be before the a.c, to d.c. conversion (obviously) and since your VTVM is alleged to go up to 500 MHz, at UHF, a tuning arrangement with a high input impedance and also something that isn't large and cumbersome will present a formidable design challenge. And then there is question of calibration to consider. Obviously, at lower freqs. - say up to about 30 MHz - that design requirement becomes a lot easier. So there is some room there for a design approach, dependent on your anticipated need, frequency-wise.
Al.
