[TenTec] Palstar tuner

[Dr. Gerald N. Johnson]

On Thu, 2009-05-21 at 19:25 +0100, Steve Hunt wrote:
> That's not true of all baluns. The flux in the ferrite core of a 1:1 
> Guanella balun wound with coax depends on the common-mode current, not 
> on the differential-mode current; so it's not directly related to the 
> load Z.
> 
> Also, we shouldn't confuse heating with saturation. To quote W8JI: "We 
> often assume heat means a core is very lossy or is "saturating", but 
> *t*his often isn't true." " It is almost never core saturation, unless 
> the core is subjected to very low average power and very high peak power 
> levels."
> 
> Steve G3TXQ
> 
Nearly aways the balun on a tuner is a voltage balun and it is sensitive
to applied voltage. Voltage is what saturates the core through the
magnetizing inductance. With power applied, a high impedance gets high
voltage a low impedance gets low voltage. With a high impedance load its
more likely to saturate and thus heat the core. And when a core
saturates for part of a cycle the inductance of the winding goes way
down.

Its OFTEN core saturation when the core area is not chosen to be large
enough. 

73, Jerry, K0CQ