Re: Balun

[peteh@xxxxxxxxxxxxxxxx (Pete Hall)]

In message <v03102803b00c370c1f82@[199.183.45.88]>, From PaulMmn 
<PaulMmn@ix.netcom.com>, the following was written:
> If both are balanced, the big difference would be the impedance and
> voltages in the circuit.

That's what they told me in school. A balun is basically just a
transformer that matches two different impedances. If impedances aren't
matched, you lose a lot of power. Consequently, components heat and
signal strength is attenuated. Take a common example:

8 ohm output impedance from an audio amp at 50 V.
2 8 ohm speakers in parallel - put a second speaker in the kitchen (= 4
ohm impedance) amplifier output power is 8 * 50 = 400W (p = ei)
A lot of the output never makes it to the speakers.
Since by ohms law, i = e/r = 50/8
And since power also can be stated as p = i*i*r 
Using the same voltage and current throught the 4 ohm output, (2500/64)
* 4 = 156.25W The balance of the output (243.75W) is in heat, mostly
generated in the amplifier collector circuit. There is a phase shift due
to circuit inductance, but not enough to change the results a lot.

I can't believe I still remember any of this stuff.

Pete


--
 - Pete Hall peteh@earth.inwave.com
http://www.inwave.com/~peteh/

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