Hi Jeff
The October 1934 issue of Proceedings of the IRE, Vol 22, #10, pages
1151-1180 has a fairly detailed description of the design of the 500
kW rig. It was written by J. Chambers of Crosley Radio Corp, L. Jones
of RCA, G. Fyler of GE, R. Williamson of GE, E. Leach of GE and J.
Hutcheson of Westinghouse. Sort of the who's who list of high power
transmitter engineers in 1930s. But it doesn't show the coupling
coef. of that transformer. 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
>
>Date: Tue, 16 May 2006 22:02:36 EDT
>From: Xmitters@aol.com
>Subject: Re: [Amps] WLW 500 kW transmitter
>
>
>Will,
>
>Harris had no involvement with the WLW 500; RCA acted as the general
>contractor, General Electric designed all RF and Westinghouse
>designed the control
>circuit, motor-generator sets, audio and modulator and all "iron" for the
>project. RCA did assign a model number to the transmitter; the 500A.
>The person doing
>the preservation happens to work at Harris and has an intense interest in
>this transmitter as I do.
>
>The 500 kW was not fired up on the year 2000 but the Western Electric 7A
> 50 kW "exciter" for the 500 kW was. The 500 kW rig has not seen power in
>decades. Too much of it has been scrapped out to ever allow the rig
>to work again.
>
>
>The k factor for the coefficient of coupling I'm using I got from an
>iterative process using the standard formulas out of Terman for
>coupled coils. for the
>given circulating current in the RF PA primary k=0.143 gives me the proper
>reflected resistance from the secondary back to the primary and it
>also gives me
>a Mutual that gives me a believable Es at the secondary that results in a
>reasonable RF output voltage. The question is, is a k of 0.143 a
>practical figure
>for two coupled flat spirals, or is this much coupling too tight to be
>practical?
>
>
>
>Jeff Glass
>
>Northern Illinois University
>
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