CTR2-Mini is available as a PCB kit 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.

Complete units come with everything you need except the CAT5 cable to connect the Mini to the Radio I/O module and cabling to connect the the Radio I/O module to your radio. Complete units include the CTR2-Mini board, the acrylic stand (you choose left of right-hand encoder), one radio I/O module, a Wio Terminal, and an SD card. The Wio Terminal has the eRPC firmware update installed and the latest CTR2-Mini firmware installed and will be fully tested before I ship it to you.

For those that want two Minis I have a new dual Mini enclosure that puts them side by side. There’s a photo of it below.


Many hams like to build things from scratch and have their own junk boxes full of parts they’re just aching to put to good use. For these hams, I offer a printed circuit board kit. This kit includes PCBs for the Main, GPIO interconnect, Encoder, and one Radio I/O module. SMT devices are preinstalled as shown in the photo below. Use the Mouser BOM project link below to order the through-hole parts and Wio Terminal to complete your kit. The CTR2-Mini PCB kit below can be ordered on the order form.

Mouser BOMs

I do not supply the through-hole part required to build the Mini. 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.

When you complete PCBs they will look similar to these, but will be the latest revisions of each board.

Enclosure Options

I can supply fully assembled enclosures for either right-hand or left-hand mounted encoders, or for two Minis mounted in the same enclosure. The right-hand version, CTR-Mini-ENCLOSURE-R, has the encoder/speaker mounted to the right of the display as shown below whereas the left-hand version, CTR-Mini-ENCLOSURE-L, has the encoder/speaker mounted to the left of the display. Choose the one that best fits your operating style.

Enclosures come with the base pre-assembled as shown below, one Encoder/Speaker and one Radio I/O enclosure, two 2mm screws to mount the Wio Terminal to the base and mounting hardware to mount the Main PCB. A 1.3″ knob is provided for the encoder. Silicone rubber feet are included.

Right-hand enclosure kit
Left and Right-hand CTR2-Minis

Single Mini enclosures come with the following items:

  • 1 ea. Assembled CNC cut acrylic stand
  • 2 ea. CNC cut Hammond 1551HBK enclosures – one for the encoder/speaker and one for the radio I/O
  • 4 ea. M3 screws, standoffs, and nuts for mounting the main board to the stand
  • 2 ea. M2-5mm machine screws to secure the Wio Terminal to the stand
  • 4 ea. tapered screws for the Hammond enclosures
  • 4 ea. silicon rubber feet
  • 1 ea. Black 1.3″ knob with finger dimple

A Dual-Mini enclosure is also available. It can hold two Mini boards, two Wio Terminals and two encoders and speakers. This is an ideal solution if you want to run two Minis to control different slices on your Flex radio or both VFOs on your FTdx101. It also makes a pretty compact SO2R interface when used with the CTR2-Mini SO2R Controller. This option is also available as a completely assembled and tested.

The Dual Mini enclosure comes with the following:

1 ea. Assembled CNC cut acrylic dual Mini stand
4 ea. CNC cut Hammond 1551HBK enclosures – one for each encoder/speaker and one for each radio I/O
8 ea. M3 screws, standoffs, and nuts to mount the main boards to the stand
4 ea. M2-5mm machine screws to secure the Wio Terminals to the stand
8 ea. tapered screws for the Hammond enclosures
6 ea. silicon rubber feet
2 ea. Black 1.3″ knobs for the encoders

Assembled Dual Mini

Select CTR2-Mini-ENCLOSURE-R, CTR2-Mini-ENCLOSURE-L, or CTR2-Mini-ENCLOSURE-DUAL on the order form for these enclosures.


For those that don’t enjoy building equipment, or simply can’t do it anymore, I offer a completely assembled and tested, custom built CTR2-Mini. These units include one radio I/O module. You only need to provide the CAT5 cable to connect the Mini to the Radio I/O module and the cables to connect the Radio I/O module to your radio for a complete system. There are three options to choose from depending on where you want the encoder mounted or how many Minis you need.

NOTE: The dual Mini option keeps both Minis together (say in back of your keyboard). Order a left and a right-hand Mini if you want to be able to place each Mini in a different location in your shack (say to each side of your keyboard).

I can also supply units without a Radio I/O module for Flex radio users at a reduced cost. Just select the Delete Radio I/O option on the order form.

  • CTR2-Mini-ASSM-R comes with the stand, assembled and tested PCBs, one Wio Terminal, and one Radio I/O module. The encoder is mounted on the right-hand side (as shown in the next photo)
  • CTR2-Mini-ASSM-L comes with the stand, assembled and tested PCBs, one Wio Terminal, and one Radio I/O module. The encoder is mounted on the left-hand side (as shown in lead photo)
  • CTR2-Mini-ASSM-DUAL comes with the dual Mini stand, two sets of assembled and tested PCBs, two Wio Terminals, and two Radio I/O modules as shown in the photo above.
Assembled Right-Handed CTR2-Mini with Radio I/O Module


If you’re going to build your own Mini you’ll need at least one Radio I/O module. One Radio I/O PCB is included in the Mini PCB kit and one module is supplied with the complete unit. You’ll need to order the through-hole parts from from the BOM to complete the unit if you’re building it. The photo below shows an assembled radio I/O module awaiting final assembly.

To use more than one radio, build one Radio I/O for each radio and connect them to the Mini 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 I can supply PCBs or assembled units without the Radio I/O board/module. The Mini’s firmware allows you to send both PTT and KEY commands to your radio over the WiFi connection so a physical Radio I/O module is not required. Just indicate on the order form if you want me to remove the Radio I/O module from your PCB kit or complete unit.

NOTE: I still have some Flex-only units available. These units don’t include the main board or speaker for the sidetone (no main board = no paddle input and no sidetone). These were intended for users that only wanted a physical tuning knob, memory management, and linking capabilities between slices for their Flex radio. This unit supports WiFi PTT control when programmed to the [C] button, but not WiFi KEY control (again, no paddle circuit or sidetone). Contact me if you’re interested in an assembled unit.

If you ordered a Flex-only unit in the past and would like to upgrade your unit to include the main board and sidetone speaker, contact me for the price of the upgrade kit.


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 or other requirements.