[R-390] R390A Carrier Level Meter Question

[DCrespy at aol.com]

Dennis,  
 
I assumed you were asking to decide on a substitute?  If so: the  problem is 
not the full scale current, it is the internal resistance of the  meter.  
 
Most 1ma movements are 100 ohms.  The R-390A needs (if I remember  right) 18 
ohms.  I have successfully used up to 38 ohm movements  with completely 
comparable results.  100 ohm movements just do  not work.  If you are thinking of 
shunting a meter, the problem is the  same.  Most 100 microamp meters are 1000 
ohms, so shunted, you still wind  up with a 100 ohm / 1 ma meter!  The 38 ohm 
meters I have used  (International brand) had a series internal resistor, that 
when  removed dropped the meter resistance.
 
Good luck and have fun!  73
 
Harry  KG5LO
Saline MI 
(home of a dozen meters that fit, but don't)