|
I really doubt that any decent modern meter presents a danger to battery tube filaments. Most of these require a filament current of 150 milliamps to operate, although some tiny hearing aid tubes require only 20 or 50 milliamps. I spot checked a couple of modern DMMs and found that they only supply less than 1/2 milliamp to measure ohms... not a problem! Although many DMMs are *powered * by a 9 Volt battery, the current supplied for resistance measurement is indeed quite small.
I have no doubt that somebody at some time, using a very primitive ohm meter did, indeed blow a filament of a battery tube (I have read the same warnings before in old electronics magazines), but it is highly unlikely with decent modern meters.
If concerned, simply *measure* the amperage delivered by your ohm meter in various ohm ranges.
jr
Last edited by jr_tech; 11-03-2013 at 01:06 PM.
|