K2 Internal Option Basics

The Elecraft® K2 is …

1. A fun-to-build HF transceiver kit with one of the hot­test re­ceiv­ers mon­ey can buy!
2. Ideally suited to portable use due to its small size and in­cred­ibly low re­ceive pow­er con­sump­tion.
3. An excellent “first rig”, with a bar­gain $659.00 in­tro­duc­to­ry price tag for the base radio.
4. Highly expandable/flexible thanks to ten “op­tion­al mod­ules” (op­tions) which can be in­stalled in 431 con­fig­ura­tions.

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 K2 as­sem­bly method and 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 either 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 (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 based K2 kit while every­thing that’s shown cross-hatched is op­tion­al.  The KIO2 in­cludes a small ‘ Y ’ split­ter board per­mit­ting 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.

Updated at 1144 UTC on Sunday 14 SEP 2008