[TowerTalk] balun testing

[Steve Hunt]

Take a look at the voltages in the example I worked using your 
impedances. There would be no difficulty at all designing balun windings 
to handle the 452v rms (639v peak) differential-mode signal for a 1kW 
level; and of course there is no core dissipation arising from the 
differential-mode signal.

In these OCFD applications the limitation is nearly always the core 
dissipation arising from CM current driven by the CM voltage across the 
CM impedance. The 669v rms CM signal from that worked example would mean 
a dissipation of 45W in the "lower" choke of a 4:1 Guanella balun with a 
Zcm of 7000 Ohms (5000+j5000).

I can't think of any application - including at the output of a tuner - 
where the CM dissipation is not the limiting factor rather than 
breakdown voltage.

Steve G3TXQ


On 25/11/2015 21:16, Jim Lux wrote:
>
> That would depend on whether the voltage is important beyond power
> dissipation.  You could test breakdown voltage in another (more 
> convenient) way, e.g. hi-pot type testing.
> (or if you wanted a "realistic test load" for applications engineering 
> advice, beyond the "testing" aspect)
>
>