[Elecraft] More Balanced Current Measurements - Voltage Balun

[Phil & Debbie Salas]

"Heat means LOST POWER. Virtually all baluns like the BL2 use Fair-Rite #61
(or something quite similar). Download 
http://audiosystemsgroup.com/RFI-Ham.pdf
and study Fig 6, the loss characteristics of Fair-Rite #61. The loss begins 
to rise above 10 MHz, and it isn't pretty above about 20 MHz."

The figure referred to is using the material as part of an RFI suppression 
choke where you want attenuation at RF frequencies.  I think you'll find 
that when the Type 61 material is used as a transformer, it will have very 
low loss if designed properly.  See Sevick's book on baluns and ununs.  But 
I think that even a well-designed transformer will have maybe 1-2% loss.  At 
100 watts, that is 1-2 watts which will cause the transformer to heat up. 
Just dissipate 1-watt in a resistor with your DC power supply and feel the 
heat.

Phil - AD5X