[ARC5] Why an UNUN?

[Mike Hanz]

On 10/24/2012 11:03 PM, Neil wrote:
>> A transmitter does not present a "load" as such to the input end of a
>> transmission line.
> Actually it does, to the power reflected from a mismatch.
> And in the real world, there is ALWAYS reflected power,
> no matter how minute.

Thanks for articulating what I was originally thinking when I wrote the 
initial statement, Neil.  My bad...I should have been more specific.

Nothing on earth seems to generate as much controversy as antennas and 
matching.  I normally try to stay out of the discussions because there 
is so much violent agreement, usually caused by misunderstanding terms, 
as Bruce Long rightly pointed out in his note.  Here's the way I see it:

We have folks who just want to get a transmitter up and running on the 
air with their particular antenna(s), which run an almost infinite gamut 
of types and sizes.  They aren't concerned with losses in a long 
feedline or anything - they just want to get a signal out and start 
talking.  For them, a simple series capacitor is all that is needed for 
a command transmitter.  It's always worked, it always will.  They are 
justified to look askance at folks who are continually fiddling around 
with adding an unun and other components to their antenna system.  There 
is nothing wrong with their position...for *them*.

Then we have the guys who are dissatisfied with anything less than 
operating their set like it was operated back in the day.  They're 
frustrated with the wimpy antenna current readings on the antenna relay 
meter.  They want to see a sharper dip when tuning up. They're trying to 
lower losses so they get an extra watt or two on the air, never mind 
that it won't mean the difference between making a contact or not.  To 
them, it's more about the pursuit of hardware excellence than making DX 
contacts.  There is nothing wrong with their position either...for *them*.

The trouble begins when a person of one group starts criticizing a 
person of the other group, not understanding where they are coming from 
- and trying to use technical information to prove it.  I've seen 
invective thrown both ways.  Once they both understand where the other 
is coming from, there is usually a sheepish grin and "sure, do what 
makes you happy."  Inside they're still telling themselves that the 
other guy is as dumb as a rock, but that's okay...at least they're not 
swinging at each other.

Anyway, I try to learn from what really good engineers have done to 
design aircraft systems, and there are a few hints there for the second 
group.  The first group doesn't care, and that's fine, too. In the final 
analysis it doesn't matter a hill of beans, and that's what I try to 
remember when the level of discourse gets warmer.

With that, the words of the old Bobby McFerrin calypso song keeps 
ringing in my ears - don't worry, be happy...don't worry, be happy...:-)

73,
Mike  KC4TOS