[Elecraft] Boots for KX1? Spurious emission limits?

[Mike Morrow]

Steve Jackson wrote:

>BTW you won't need 'boots' for your KX1.  We've found
>that, over the years, Elecrafts come built-in with mojo.

When I saw the term "boots" in the original message, it took me a moment to realize that this apparently meant "external RF amplifier" (I've only been a ham 36 years).  IMO, an external RF amp would completely spoil the fun of using a QRP rig.

I don't have a KX1, but I wonder if use of an external amplifier would be technically sound.  Wouldn't an external amp likely aggravate the spurious emission problems of most QRP rig designs?  Simple QRP transmitters often only marginally meet the relaxed spurious emission limits allowed for low power transmitters, especially when DDS RF generation is used.  According to rule 47CFR97.307, rigs of 5 watts or less have to suppress spurious emissions by 30 dB below fundamental, while those greater than 5 watts have a 40 dB limit (which is soon to become 43 dB to conform to international law).  According to QST review, the KX1 tested at 37 dB.  (The K1 tested by QST exhibited 43 dB suppression, and the K2 tested 44 dB.  Most commercial rigs of the last 20 years have figures of 50 dB or better.) 

73,
Mike / KK5F