"Ashlock,William" wrote:
Mal,
I believe what is going wrong is that many guys fail to start out with good
reference material and not 'going through the numbers' on paper. Secondly
they don't reach a basic understanding or 'feel' of how a loop performs by
getting the Rac down to an acceptable value consistent with the loop
dimensions and conductor type. They will be putting 99%+ of the power into
that Rac and it is all wasted in heat - so it better be as low as possible!
A low power level must be used for this experimentation because only a tiny
breakdown of a component will totally mess up results/conclusions/opinions.
Then comes the problem of selecting a capacitor that can handle the voltage
and current in the loop. At 1w my loops run up to 1.5A at 150v RMS... no
problem for plain old 500v micas. At 100w the current and voltage is 15A and
1500v RMS. Getting tough? Darn right! - but doable. At 1000w you are at 47A
Hi Bill
This is terrific current 47Amps. To generate 1W erp some stations in the
UK are
running 2Kw or more to their small vertical antennas. With a loop it
would be 94
Amps. In ZL to generate their permitted 5W erp from a loop it could be
nearly
250 Amps.
I think I will stick with my vertical antenna for transmitting and my
couple of
amps. I am using my loop for receive which is parallel resonated and it
works
very well, although I use the vertical for both tx/rx normally, but the
loop is
a good rx back up antenna.
With your power limit you can get away with hanging the loop directly on
the
trees but with 47 - 250 amps I expect you would start a forest fire !!
GL De Mal/G3KEV
and 4700v. For those that are this crazy, the loop conductor will have to
use #6 or multiple runs of smaller size wire and the capacitor will have to
be...... well, something exotic! My gestimation is that at 1000w you will be
exceeding 1w ERP, anyway, so this likely a theoretical design.
Bill A
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