------------ ORIGINAL MESSAGE ------------(may be snipped)
On Sat, 17 Dec 2016 10:41:53 -0500, you wrote:
>Bill,
>
>Would you please explain this a little more?
>
>I am having trouble getting my head wrapped around
>
>"... a bunch of 250 watt modules which were combined
>and switched in and out at an audio rate to produce
>the modulation"
>
>Just getting to my first cup of coffee ... and that's
>my story and I'm stickin' to it.
>
>Thanks - David KD4E
REPLY:
What the DX50 has is several racks of plug-in modules, each capable of
250 watts output. To produce the amplitude modulated output, they are
individually switched on or off at an audio rate. Each module produces
only carrier, no modulation, but the effect of switching them on or
off in a precisely controlled way produces an AM signal.
The engineers at KFI especially liked the fact that the modules cold
be "hot swapped", i.e. a failed module could be replaced while the
transmitter was running.
?At one point the tour guide took us out to the base of their many
hundred foot tower, which itself was quite impressive. They turned the
power down to only 5 kW while were at the base. That tower was later
hit by a small aircraft which brought it down, killing everyone on
board the plane, but I believe there were no injuries on the ground.
One can only imagine the chaos that caused!
That's about all I know, except for one other puzzling thing: There
was a power output meter on the transmitter which was rock steady at
50 kW. Normally, with AM the power kicks up during modulation, but
this one didn't. I don't know why. I should have asked one of the
engineers but I didn't think about it till later.
The tour was arranged by a local radio club, of which I was not a
member, but got invited anyway.
73, Bill W6WRT
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