[Elecraft] 9:1 Balun

[Lynn W. Taylor, WB6UUT]

Oh, whatever power is generated by the transmitter is going to radiate.  
The classic example of "radiating power" that is completely and totally 
uninteresting is when you dump the power into a resistor (a dummy load) 
and the power is radiated as heat.

There is a contest where the participants take whatever metal stuff they 
find lying around, load it up and operate.  It's proof that lots of 
things can work, more or less.  The light-bulb example is another one.

I know that a 50 ohm source, going through a 50 ohm feedline into a 50 
ohm load means minimal loss in the feedline.  If you have 1/4 wave of 
coax with 100 ohm load the feedline will act as a transformer and you'll 
have 25 ohms at the transmitter -- and that means power lost as heat.

It also means the length of the feedline, in wavelengths (and therefore 
frequency) matters in the overall antenna system design.

That's why the balun should not be at the radio end, it should be near 
the antenna.  If it's a permanent installation, taking the time to 
figure it out and get everything matched up is a good thing.

Ladder line is well loved because it isn't as lossy as coax when things 
aren't matched.

Tossing the radio (gently!) onto a picnic table at a park and throwing a 
wire into the air is different.  Maybe it works, maybe it doesn't, but 
you don't have a lot invested in the antenna system, and you can pick 
wire lengths that'll be "good enough" -- and "good enough" often is good 
enough.

This discussion started with what were good and bad lengths for an 
ad-hoc, non-resonant wire.  Having some sort of 4:1, 9:1 or 16:1 balun 
(or un-un) gets important if your wire happens to be near resonance.

73 -- Lynn

On 1/31/2017 5:35 PM, Kevin - K4VD wrote:
>
> On Tue, Jan 31, 2017 at 8:03 PM, Lynn W. Taylor, WB6UUT 
> <KX3 at coldrockshotbrooms.com <mailto:KX3 at coldrockshotbrooms.com>> wrote:
>
>
>     That doesn't say the antenna would radiate it, but the transmitter
>     could make power and the tuner/transmission line would deliver it
>     to the radiat
>
>
> ​Why wouldn't the antenna radiate it? Seems to me if you can deliver 
> power then what's not being radiated as heat would be radiated as RF. 
> I have weird ideas about how all this works.
>
> One thing I think would be great to have, especially built in as part 
> of an antenna tuner, is a switchable BALUN. When someone needs to 
> throw up random antennas it would be handy to be able to just switch 
> in the appropriate ratio. Can a BALUN be tapped maybe? It seems it 
> would extend the range of internally antenna tuners also. I should 
> know this stuff. But I don't.
>
> 73,
> Kev K4VD
>