[Test-Equipment] Bird Termaline Question

[Richard Knoppow]

     I found a couple of blogs on fixing Bird slugs
http://www.hamanuals.com/MMans/Dead-bird.pdf

http://www.chuckmartin.com/Wattmeter-Repairs.htm

     Also the patent is US2852741  available from Google patents or the 
USPTO site.

     Dummy loads are often made up of what amount to several resistors 
in parallel to get the final value.  This may be physically a single 
coated resistor with the coating cut into strips so that it forms 
effectively a group of parallel resistors. If one or more sections opens 
up the value goes up.  I think that is what has happened here. I am 
pretty sure its not drift. The resistance elements will be carbon film 
or metal film or even resistance wire. These are very stable with time 
and temperature unlike the familiar carbon composition resistors which 
drift up with time, heat and moisture.
    A google search for Bird Wattmeters will find some sites with 
material on repairing the meter.  I found quite a bit of general 
information on Bird loads but no specific repair instructions. However, 
this was a casual search so there may be more info there.
-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL