In a message dated 5/23/06 8:04:58 AM Central Daylight Time,
amps-request@contesting.com writes:
<< It does say that the Q of the plate
'winding' was 1200, really high for a coil made from tubing! Since
the position of the two spirals was adjustable from the front panel
(for the loading or coupling control), the coef of coupling K would
vary. I don't know if 0.143 is reasonable or not.
73
John
K5PRO
>>
John,
The coefficient of coupling figure I came up with, will reflect the required
load resistance that the 167 kW amplifier sees, to a load resistance the tube
plates want to see.
I'm actually more interested in knowing what practical values of k would
bethat are actually realizable. I don't think, for example, you could get a k
of 1
with an air core transformer. In some of my old EE texts that describe
coupled solenoid coils, k figures or .008. .010 or thereabouts, are given
I found a program on the Internet that allows the modeling of coupled coils
of all kinds. With the approximate geometry figures I have for the WLW plate
tank, I got k values around .1, but the problem now is, to what degree of
coupling does that k represent? It's pretty easy to calculate, but not so easy
to
model. I doubt that you would want the coupling much greater than "optimum"
coupling, which is 1.5 * critical. The value for critical coupling is dependent
on
the uncoupled Q of the tuned primary and secondary. The rub there is knowing
what "loading" resistance the tube would be providing while unloaded.
I think if a k value of .143 is practically realizable for two coupled flat
spiral coils, I think I will conclude my analysis at this point then. One thing
I did learn from running this coupled coil simulator is, it was much easier
getting a higher degree of coupling with flat coils compared with two solenoid
type coil physically separated by the dame distance. So summarize, I'm more
interested in knowing if a coupling coefficient of .143 is physically
attainable
than I am knowing if this K value represents loose, critical or optimum
coupling.
One might be able to make electrical measurements on the coil that is at the
site, but that 50,000 watt signal there on 700 kHz might raise heck with such
an experiment :-D
Jeff Glass, BSEE CSRE
Northern Illinois University
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