In a message dated 9/4/03 7:44:28 PM Eastern Daylight Time,
jimlux@earthlink.net writes:
My questions about measuring power have a real basis in the context
of fairly sophisticated phased array designs where the amplifiers are used
to supply reactive power instead of using passive L or C. It's not that I
want to skirt the rules and run megaQRO with specsmanship and creative rule
reading... but neither do I want to artifically restrict the power available.
I had a look at your page describing the "problem". Here is practical
(contester's) perspective.
Commercial example of such transmitting array is at HAARP in Alaska. Nice but
EXPENSIVE!
Lets just take 4-square, which would be typical, efficient phased array. I
can build phasing unit (3 relays, two toroid inductors, bunch of fixed
capacitors) for about $95, or you can buy commercial unit for about $300. Works
on
transmit and receive, simple, low losses, reliable, instantaneous. No need for
"$300 vacuum variables".
1500 W amp, used can found for around $500. Array you have to build anyway.
"Distributed" amplifiers? You need to bring the AC power to them, weather
(thief) proof them, you need LC components and tuning or switching systems with
tracking (4x). What about receive? Receive antenna has to be most
discriminating. Another bunch of matching components and switching? How much
would that
cost and then "brains" in running it?
For contesters it don't look like attractive chick. Too komplikated :-)
For those who want to play around and "explore"? Maybe, why not.
Then there is a problem of reradiation and distortion from such a setup. I
heard one HG station in the contest with raspy fuzzy signal just from such
setup
- separate antennas fed with separate amplifiers.
Not to flame or pore cold water on the project, but it would be interesting
to see if such setup was built and practical advantage shown.
Yuri, K3BU
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