Hello all. I must apologize up front for the long post. I just want to get everything out at the same time.

Now that the Mini’s firmware has finally started to mature I’ve been working on expanding the Mini’s hardware ecosystem.

Basic Mini Control

First, let’s review where the Mini ecosystem is at now. As you all know, the Mini and Mini+ provide radio control and a keyer for a wide variety of radios. It can plug directly into the radio using the available radio interface cables. This simple diagram shows this relationship.

Mini with Multiple Radios

Next, you can add a manual RJ45 CAT5 switch to control multiple radios with one Mini using one set of paddles and one PTT switch. Each radio requires a CTR2-Mini Radio I/O module and is assigned to a Radio Port in the program. You must select the Radio Port on the Mini then select the physical port for that radio on the RJ45 switch. These switches are available with 2, 3, or 4 ports and you can daisy-chain multiple RJ45 switches to add even more radios. A high quality antenna switch (>60 dB of isolation) is used to select which radio is connected to the antenna or a simple patch panel can be used. With this configuration you would need a mic and headset attached to each radio (or a way to switch them between radios).

Now for something new…

The rest of this post is about new products that are in development. As of January 20, 2023 the first round of boards have been designed and are into the board house to be built. I totally expect I missed something on one or more of the 10 new board designs but if all goes well these products should be available by March 2023.

It’s too early to have pricing for these products but as always I’ll have board kits, Mouser BOMs, and schematics so you can build your own. Fully assembled and tested units will also be available.

CTR2-Mini Radio I/O Multiplexer

First on the list is an automatic CTR2-Mini Radio I/O Multiplexer. This switch replaces the manual RJ45 switch above and will automatically select the correct radio I/O port when you select a Radio Port in the Mini. You can use a manual antenna switch as shown above or connect the four Antenna Switch Control outputs on the multiplexer to an external electrically operated antenna switch. In the configuration shown below the radio I/O circuits and the antenna are automatically routed when you select a Radio Port. The multiplexer has an expansion port so you can daisy-chain up to three additional multiplexers and antenna switches to automatically select and control up to 16 radios. A Radio I/O module is required for each radio. Not that anyone would ever need to do this (maybe a ham store showroom?), but it can be done. The multiplexers are powered by the Mini and you only need to set the address jumpers on each multiplexer so it knows which of the four radio banks it controls and set a jumper for the type of I/O module used on the radios (Radio I/O or the new Audio I/O). Each radio still needs its own mic and headset or some sort of audio switching arrangement.

Here’s the 3D mock-up of the Radio I/O Multiplexer’s front panel. It’s designed to fit into the small PacTec CM3-100 enclosure. Since there are no user controls and it takes power from the Mini it can be placed out of the way.

CTR2-Mini Audio Controller

Ok, so the multiplexer makes it easier to select one of several radios. You still have the problem of managing the Tx and Rx audio to and from each radio. This is addressed in the next new product I’m working on, the CTR2-Mini Audio Controller.

The new Audio Controller sits between the Mini and the Radio I/O Multiplexer as shown below. It’s job is to route Tx and Rx audio to and from each radio. To use this system, I’ve developed new radio I/O modules I call Audio I/O modules to differentiate them from the standard Radio I/O modules I’ve used up till now. These new audio modules contain isolation transformers for Line-In and Line-Out in addition to providing CAT I/O, PTT, and Key control. They are basically the same as the radio I/O module I developed for the original CTR2 project a couple of years ago. I’ve replaced the 12-pin terminal strip with three 3.5mm stereo jacks so they’re compatible with the radio I/O cables I have for the Mini.

Here’s a 3D mock-up of the audio controller’s front panel. It is designed for the PacTec CM5-125 enclosure. The TX ENABLE / PTT switch is center spring loaded so pushing it up toggles Tx Enable on the Mini and pushing it down keys PTT.

The MIC switch selects one of two mics and the level controls give you control over mic and headphone audio. Strapping options allow you to enable bias for electret mics, enable PTT on the Ring terminal of the 3.5mm stereo Mic connectors, or bypass the Mic amplifier entirely. The unit also provides audio output that can be connected to a USB sound card on your PC for 3rd party digital modes.

The Audio Controller is powered by 12 VDC and provides power to the Mini, Radio I/O Multiplexer(s), and the Audio I/O modules. This gives you a single power switch for the entire Mini control system.

Here’s the 3D mock-up of the Audio I/O module. It’s slightly larger than the simpler Radio I/O modules but still small enough to hide behind your radios.

CTR2-Mini SO2R Controller v2

Readers of this blog know that I’ve been working (albeit not very hard) on a SO2R controller to compliment the Link features in the Mini’s firmware. The prototype was described in this post last year. The prototype worked well but the PacTec KEU-7 sloped panel enclosure required desk space and the rear opening wasn’t well suited for the number of connectors required. In short, it just wasn’t ideal for this project.

The new Version 2 of the SO2R controller takes advantage of the new CTR2-Mini Audio I/O modules to offer a simplified cabling scheme and is designed to fit into a PacTec CM6-225 enclosure is is described in this post. The advantage of this design is that the controller can be placed on one of your radios or on a shelf leaving your desk free for other more important accessories.

Like the Audio Controller, the SO2R Controller runs on 12 VDC and provides power for both Minis and the Audio I/O modules. In fact, there are separate 5 VDC regulators in this unit so each Mini has a dedicated power supply.

The simplified diagram below shows the connections required. The SO2R configuration is similar to the Audio Controller configuration described above as it offers common Tx and Rx audio, keyer, PTT, and straight key inputs that are shared between the radios. The major difference between the two configurations is that the SO2R controller provides a dedicated Mini to control each radio and it provides instant switching between the two radios by just enabling Tx on the desired Mini or SO2R controller. In addition, separate A and B Tx and Rx level controls are provided, a switch matrix in the two Rx audio streams allows you to control how the Rx audio from the two radios is sent to the headset, and the two Minis can be linked together to provide synchronous tuning on either the same frequency (for receiver diversity) or on separate frequencies (dual band S&P).

Here’s the 3D mock-up of the SO2R Controller’s front panel. I finalized this design before working on the Audio Controller that uses the center spring loaded toggle switch for Tx Enable and PTT instead of two pushbuttons to toggle Tx Enable. It the toggle switch works well with the Audio Controller it would be easy to adapt it to the SO2R controller.

SO2R with Backup Radios

Now admittedly, this last configuration is way out there because any serious contester that requires warm-standby radios won’t be using CTR2-Mini as their main controller. I just present this as a example of what the modular design of the CTR2-Mini ecosystem is capable of supporting. In fact the system below could be expanded to 16 radios on each Mini. I have no idea of why you might want to do this, but in theory it could be done 🙂

This diagram also shows the CTR2-Mini Dual-Port Antenna Switch Controller in use. Either CTR2-Mini Antenna Switch Controller can be used by any of the other configurations above and it can be located away from the operating position because either Mini can control it over WiFi.

Winding down

I hope this gives you some ideas of what the Mini will soon be capable of in the near future and how you might expand your own Mini or Mini+.