The new CTR2-Mini+ offers many additional features at a lower price point then the original CTR2-Mini that was featured in the September 2022 issue of QST. It also causes undue confusion for those considering the purchase of a Mini since both are featured throughout this blog.

In order to simplify things, I am migrating the original Mini information from the main blog to the Archives area. I still have PCBs and acrylic enclosures available for the original Mini so if you’re interested in building or purchasing an assembled unit contact me for discounted pricing information.

CTR2-Mini+ units are available as PCB and enclosure kits for those that prefer to build their own gear or I can custom build a complete unit for you if you don’t want to build your own.

The assembled Mini+ units come in a PacTec KEU-5 sloped panel enclosure. The Wio Terminal on the unit has the eRPC firmware update applied and the latest CTR2-Mini firmware installed. Assembled units are fully tested before shipment. They do not include a Radio I/O module because the radio I/O circuit is built-in. If you plan on controlling more than one radio you’ll need to order a Radio I/O module for each radio you want to control.

In order to connect the Mini+ to your radio you’ll also need to order or build specific radio interface cables. The Radio I/O Cable page can help you determine which cables you need. They can be ordered when you order your Mini+ or Mini or you can build your own.

CTR2-Mini+ PCB Kit

For those wishing to build a Mini+ order the CTR2-Mini-Plus-PCB-Kit. This kit includes the front panel PCB, Base PCB, back panel, and mounting hardware. The dual-row 20-pin header for the Wio Terminal GPIO is pre-installed for you as are all the surface mount components.

The new CTR2-Mini+ PCB Kit can be ordered on the order form.

CTR2-Mini+ PCB kit with mounting hardware

Mouser BOMs

I do not supply the through-hole part required to build the Minis. Instead, I have created custom Mouser BOMs (bill of material) that you can use to easily order the necessary through-hole components to complete the PCB kit above. You can order directly from Mouser or use the BOMs to order the parts from your favorite supplier. You can find the BOMs and schematics here.

CTR2-Mini+ Enclosure Kit

The CTR2-Mini+ uses the KEU-5 sloped panel enclosure produced by PacTec. It is included in the Mini+ BOM on Mouser. You will need to drill out the PCB mounting holes and grub out most of the recess on the front panel (leaving a 1/8″ rim around it and flanges for the mounting holes. The CTR2-Mini+ Assembly Manual includes a template for preparing the enclosure. If you don’t want to bother with grubbing this enclosure, I offer a fully CNC machined KEU-5 that you can just mount your finished Mini+ PCBs in. Select CTR2-Mini-Plus-ENCLOSURE on the order form for this enclosure.


For those that don’t enjoy building equipment, or simply can’t do it anymore, I offer a completely assembled and tested CTR2-Mini+ units on the order form.

You’ll need custom radio interface cables to connect to your radio. Visit this page to find out which cables you need for your radio. Radio interface cables can be ordered on the order form.


If you want to control multiple radios with your CTR2-Mini+ you’ll need to order a Radio I/O module for each radio to be controlled. You can order just the PCBs and machined enclosures to build them yourself or I can provide assembled units. If you’re going to build your own order one set of the through-hole parts from the Mouser BOM for each unit you are building. The photo below shows an assembled radio I/O module awaiting final assembly.

NOTE: The Radio I/O module is not required for the CTR2-Mini+ if you’re only going to control one radio as it has a built-in radio I/O circuit and has CAT and PTT/Key Output jacks for the radio interface cables to plug into.

To control more than one radio with the Mini+, build one Radio I/O for each radio and connect them to the Mini unit through a manual RJ45 switch. Just select a port on the switch and then select the same Radio Port in the Mini to connect to each radio as shown in the diagram below.

Using multiple radios with CTR2-Mini


For those that only want to use their Mini on a Flex 6000 series radio you can easily build an encoder and function keypad interface for your Wio Terminal. I don’t supply enclosures for this configuration. Many have used the PacTec KEU-5 enclosure I use for the Mini+ as it’s the right size for this configuration.


If you build this circuit make sure you connect the case of the encoder to ground as shown. Failure to do this will cause static discharge to damage you Wio Terminal. Yeah, I found out the hard way!


By default, CTR2-Mini+ uses solid-state Key and PTT outputs to your radio. These work great for newer rigs but older tube rigs typically use negative polarity grid-block keying so these outputs don’t work so well. The Mini+ has the option to add reed relays and snubber diodes to convert your Mini+ to dry-contacts that can switch 200 volts at 1/2 amp. To upgrade your Mini+ to use relay keying order the two relays and two diodes on this BOM.

You’ll need to cut two jumpers and add the relays and SMT snubber diodes to the board.

You can use the CTR2-Mini Order Form to order the options you want or you can contact me directly if you have questions, would like to order the original CTR2-Mini instead, or have other requirements.