The Elecraft® K2 is …
The tiny K2 is able to support so many options, because six of the ten install in the same physical space and use the same electrical connections as another option or group of options. This is why its ten options can only be installed in 431 (rather than 210 – 1 = 1023) combinations. Borrowing terminology from probability theory, it could be said that the installation of most options is mutually exclusive with the installation of other options; meaning that you can only install one or the other, but not both at the same time. So even though ten options are available, at most only six (for the QRO configuration) or eight (for the QRP configuration) can be installed in a K2 at the same time.
Figuring out which option combinations are valid can make contemplating your initial K2 purchase seem a bit overwhelming at first, even before considering our rework-free “Option Ready” K2 assembly method and our Rework Eliminator™ aftermarket accessories. Fortunately this subject is easy to understand with the aid of an illustration.
Referring to the diagram below, six Elecraft® options (the K60XV, K160RX, KNB2, KSB2, KAF2, and KDSP2) plug directly onto the K2’s RF or Control circuit board via one or more Single Inline Package (SIP) connectors. These are the options that can be quickly interchanged with our Rework Eliminator™ option bypass headers, (A.K.A. un-modules). The other four Elecraft® options mount inside the top cover and connect to the K2’s main circuit boards via cables. Un-modules are not applicable to these options.
As already mentioned, the installation of some options or option combinations is mutually exclusive with other options. Specifically, you can install either of two auxiliary audio filters on the Control board – either the original analog filter (KAF2) or an advanced digital signal processor (KDSP2). You also have a choice of either the QRP top cover options (KBT2, KAT2, and/or KIO2 in any combination) or the QRO top cover (KPA100). The four options (K60XV, K160RX, KNB2, and KSB2) that mount on the RF board, are the only ones whose installation is not mutually exclusive with other options. They each have their own dedicated mounting location and can be installed in any combination.
Connector P4 (Aux I/O) on the Control board is included with the base K2 kit, while everything that’s shown cross-hatched is optional. The KIO2 includes a small ‘ Y ’ splitter board which allows both the KIO2 and the KAT2 to connect to P4 at the same time. Plugs RF-P6 (Aux RF) and RF-P3 (Aux 12V) are supplied with each of the options that require them.