[Elecraft] dmm vs vom

[AJSOENKE at aol.com]

In a message dated 10/8/2008 11:03:32 A.M. Pacific Daylight Time,  
knowkode at sbcglobal.net writes:
Hi all,

Is there any problem using a  VOM instead of a DMM to perform the resistance 
checks while building the K3? I  have yet to make it fully into the modern era 
and to that end, do not have a  DMM.

Tnx es 73,
Jim  W5QM


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Generally it is not a problem, if you are checking resistors. The area you  
can get into trouble is when you have semiconductors connected to the circuit - 
 Elecraft Rigs are loaded with them. The problem can come from most VOMs not  
being able to limit the current applied to the circuit under test. Even at 
low  voltage you could apply a voltage with enough current to bias a transistor 
to a  destructive level. Most DMMs use a high impedance amplifier on input to 
reduce  current flow to/from the meter. The resistance circuitry can also be 
made to  sample E/I data at low enough levels to provide resistance measurement 
at much  lower current and voltage. IMO, with many DVM/DMMs on the market at 
low cost,  it's probably not worth the risk.

Al WA6VNN
 



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