KPA500: Integration with K3

[Guy, K2AV]

On Fri, Sep 10, 2010 at 11:43 AM, Bob Nielsen <[hidden email]> wrote:
> There is the little matter of Part 97, Section 97.317, which limits amplifiers to 15 dB gain (10 watts in -> 316 watts out).

Ourselves as individuals, we can build for ourselves (or modify) an
amp to other gain figures.  Amazing what one can do with a pair of
4X150's in this same app.  There was a period where SSB exciters were
10 and 20 watts, followed by tetrode and pentode amps that easily put
out 600 or 700w PEP (I know, I know, only real old old farts know
about those).

Without a schematic, it is hard to tell, but 17 dB (10 watts in makes
~500 watts out) is still way less than the 23 db "natural" gain of the
transistors.  It is probable that the 15 dB is using some degree of
feedback that most likely can be mildly modified by the owner to 17 dB
to make a natural "pair of shoes" for a 10W K3 or K2.  Wayne of course
is precluding from offering that as an option or modification kit.
But he doesn't have to preclude it with a Microsoft style "licensing"
agreement forbidding modification, either.

Thinking in that vein....

One thing that would be quite nice: The external KPA100 and K2 share
an auxbus, and the K2 knows when it is attached and ready, the power
adjustment display in the K2 tells what is available, and if the power
knob is dialed down to a barefoot power level, the KPA100 drops out
and indicates low power range, or dials up above some wattage, kicking
in the amp up to 100.

IF the KPA500 would only extend to 500 watts with 10 watts drive in an
Auxbus linked mode aka external KPA100, does that not satisfy the FCC
requirement in the same fashion the KAT100 only runs with the K2?.
And of course the K3 PWR control would now scroll from 1 watt to 500
watts, kicking in the KPA500 as needed.

I think for a lot of people, that would allow them to ignore the K3
100w amp and go directly to the KPA500 and yet to be anounced matching
Auto tuner.  AND use that cavernous space vacated by the KPA3 and KAT3
 for stuff like a built-in power supply designed for hams and zero
RFI.

Or simply have a mild variation of the KPA500/autotuner combo that
simply only runs integrated to a K3/10 or K2/10.

Or one could have a combined KPA500/KAT500 integration/K3 power supply
module that goes in the KPA3/KAT3 space which includes an always used
robust 17 watt boost amp and isolation stage which drives the KPA500
as is, and when that's installed the K3 PWR display scrolls from 1 to
500.  Brick on Key.  Same deal for the 1.5 kW version.

Of course, the FCC could always accuse us of only wanting 500 watts as
a driver for a 3CX10000A7 and clamp down, makes as much sense as the
CB thing.  They can use it that way in Italy as an export model (I've
already told you about I9xxx who is an honest to god 40-45 over S9 on
40 with a calibrated K3 S-meter, right?)

Just thinking out loud.

73, Guy.
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