The “Twins,” as I like to call them, are an Elecraft K2 and a separate KPA100 in an EC2 box, possibly with the KAT100 antenna tuner.
Every so often I get a request to build one. The combination is especially appealing when the barefoot K2 already has the KAT2 installed and the owner wants to take just the QRP rig on outings.
It’s a straightforward build. Here are some photos to show you what it looks like (click each for larger image) …
When you’re using this setup, be sure to apply power to the KPA100 first. Then, when you turn on the K2, it can properly discover that it has an amplifier to work with. Pressing “tune” on the K2 will activate the KAT100 tuning, even though there’s a KAT2 hooked inside the K2. Switching antennas doesn’t change the K2 output: it changes the KAT100 antennas. It’s a good idea to hook your dummy load to the KAT100’s “Ant 2” just in case you select it and go key down. Convenient too.
If your KAT100 isn’t already in the EC2, you’ll need both the EC2 project enclosure and the KAT100PNL panel kit to make this conversion with the KPA100. Elecraft has additional info on their antenna tuner page. You’ll need to provide the BNC-BNC cable between the K2 and the tuner, and the PL-259 cable set between KPA-100 and the tuner. Your K2 will need to have the KIO2 option installed to communicate with the new twin.