[Elecraft] K2/100: Three ways to switch from QRO to QRP

[Wayne Burdick]

I wanted to do a brief summary following all of the questions regarding
how the K2/100 can be switched between QRO and QRP modes.

Since it was important to us that the K2/100 remain true to its QRP
roots, we've made it very easy to drop into an efficient QRP mode. There
are three ways to do this:

1. Turn the POWER knob to 10 watts or lower. The 100-w final is put into
"thru" mode at this threshold (you'll hear the RF bypass relays click on
the KPA100). In this "auto-QRP" mode you can set power from 0-10 watts
in 0.5 watt steps. (Above 10 watts, you'll have 1-watt steps to slightly
above 100 watts.)

2. In the menu, set PA to OFF. This puts the final into thru mode and
restores the K2's normal 0-15 watt POWER control range (0.1 or 0.2 watt steps).

3. Turn off just the high-current power supply, leaving the K2's normal
low-current supply connected. This again drops the rig into the 0-15
watt range. 

We included this dual-supply operating feature specifically to handle
field and emergency power situations, which the K2/100 will be ideally
suited for. The low-current supply could be a small 12V gel-cell or
motorcycle battery connected to a solar panel, for example. This supply
is completely diode isolated from the high-current supply, and it will
switch in automatically if the power mains go down. (When you turn the
high power supply off, you'll see a confirmation on the K2's LCD: "No PA
PS". When you turn the supply back on, you'll see "PA PS On".) 

Perhaps the K2/100 is the world's first Uninterruptible Desktop
Transceiver  ;)

In all cases, QRP or QRO, the total current drain of the K2/100 in
receive mode remains well below that of other 100-watt-class transceivers.
 
73,
Wayne
N6KR