|[AMRadio] Re: new antenna and matchbox a bust.|
jpl15 at panix.com
Tue Jan 30 17:12:58 EST 2007
On Tue, 30 Jan 2007, ne1s wrote:
> So what's not balanced?
Given two lengths of coax, connected as per the Original Description -
center 'hot', shields connected at each end and grounded:
Resistively - perhaps at dc-to-some-very-low-frequency - this
configuration will handle a 'balanced' circuit, in which both conductors
are 'hot' and both are referenced equally to ground.
As the frequency increases, the lumped-constant parameters of the device
as a whole comes into play - just what kind of play, I haven't a good idea
(yet). Also - this is a fairly complex transformer, IMHO.
And while I'm not sure if parallel-adjacent coaxial cables retain the
characteristics we call 'balanced' at HF RF freequencies - its for Damn
Sure that terminating this device in a balanced-output antenna tuner on
one end, and in a run of classic ladder-line (of some signifcantly other
impedance) at the antenna end - all this forms some kind of complex
transformer / attenuator / network - the exact electrical nature of which
I haven't the skills to accurately infer at this moment.
I do know it's probably not "optimal".
I also know that if, as a classic 4-terminal black box, you like what
comes out as a result of what goes in... and 'not blowing stuff up' is a
part of "like" - then I'd be of the opinion that It Ain't Broke.
So don't fix it..... ;}
Someone did an article in QST sometime in the last 20 years or so - on
pretty much the same subject. They decided to do the opposite of careful
and scientific antenna design. They used some small rig and a tuner and
set about seeing just how many Things (of all descriptions) they could get
to load-up - and have a QSO thereupon. They talked on a table lamp
(unplugged from the wall, natch) - a chain-link fence, an actual
screwdriver, a wire coat-hanger, ect ect. The moral of the story was
just as others have said - if it works, it works. If you're happy with
how it works, well, cool!
If on the other hand, getting an antenna system 'perfected' is your goal
- that's an enjoyable part of the Hobby, as well....
My 200 millidollar....
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