David, I was over simplifying when I said "voltage". Voltage is important but current plays a huge role too.
My DMM's (4 of them, one a Fluke) produce less than 0.6V except on the lowest resistance range. On the highest resistance ranges the voltage is 0.2 V or a bit less. On the lowest resistance range, the voltage increases to over a volt, but it's current limited to less than 1 mA. That's where the d'Arsonval meter movements have trouble. Even the venerable Simpsons need more current to operate the meter mechanism than is safe for the circuit under test with most modern electronics. Junctions will start to "turn on" at somewhere between 0.2 and 0.6 VDC, depending upon the silicon material used. That's why the readings can be changed greatly by the orientation of the test leads. Ron AC7AC -----Original Message----- From: David Christ [mailto:radio...@mchsi.com] Sent: Monday, February 21, 2011 2:15 PM To: Ron D'Eau Claire; elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 RF Board Resistance Checks What is the maximum safe voltage? It must be less than 1.5 v as that is what the Simpson and Triplett VOMs use in their lower ranges, but how much less? David K0LUM At 3:47 PM -0800 2/20/11, Ron D'Eau Claire wrote: > > >I trust you are using a DMM and not a VOM (like the old Simpsons, etc. - >just about anything with a "wiggly needle" meter ;-) All of the older >meters applied a dangerous amount of voltage to the circuit for today's >solid state components > >Good luck! > >Ron AC7AC > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
