[Elecraft] Re: More Quests: Driving (big) linear amps withthe K2?

[George, W5YR]

"Mark J. Dulcey" wrote:

> > The Harris amplifier as briefly described would appear to violate Part 97
> > if driven to a KW output with 100 mw input. That is 40 db of gain . . .
> 
> The input power and gain restrictions apply to amplifiers that are
> manufactured and sold for the amateur service. Amateurs can build
> amplifiers for their own use, or adapt amplifiers from other services,
> that don't fall under those restrictions.

That is correct, Mark, as stated in 97.315 (b)(3)(ii) - beginning to sound
like a lawyer. If only one amplifier is modified per calendar year by the
licensee for use only in the licensee's station, then it need not follow
the requirements for amplifiers certificated for amateur service.
> 
> The spectral purity issue, however, is a real one. Any signal put on the
> amateur bands must comply with that regulation. The spectral purity of
> the K2 may or may not be an issue, depending on how good it is, and on
> how much bandpass filtering, if any, is done by the amplifier. (Any
> reasonable amplifier will have low-pass filtering, so harmonic radiation
> shouldn't be a problem. But in-band and near-band spurs could be.)

Yes, I think that this is the real "hooker" in this scenario. Not only must
the total spurious component power level not exceed 50 mW, regardless of
output power level, all spurious components must be at least 40 dB below
"the mean power of the fundamental emission."

I have no doubt that the 100-watt amplifier modification for the K2 results
in a completely legal transmitter, but one wonders how much additional gain
can be used before running into either the 50 mW wall or the -40 dB wall or
both.

Thanks for the note and for reminding me that as amateurs we are permitted
to do things that other services are not.

73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
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