Hello everyone. Want to share another project for who like spend time with smelling flux and solder. The project is – Simple CAT Interface.
I guess everyone knows what it CAT for, no isn’t CAT or DOG. Most of us have the cable CAT interface which we use to control our rig from computer. The standard cable is a simple converter from one level to another ans usually based on MAX232 IC. But how about make it cordless? Let say it in other words – make it wireless or Bluetooth device. Sounds good, doesn’t?
This project is not new or something breathtaking and have been successfully done many times. So you can find a lot of information online, just Google It!
What I want to share is just How You Can Do It By Yourself in simple way. Make it for yourself or ether better make it for your Dad or Mom as a present. That would be a great present ever.
Just remember one thing that you will not find something like this on the market so it would be awesome gift. Let’s start.


HC-05 Module 100% Compatible with: YAESU FT-857/D, FT-817/ND, FT-897, FT-100D 

Available with custom settings (baud speed up to 38400 bps, name, password and etc)

The new version of HC-05 which I have in my store on eBay compatible with Android OS and RX/TX App by YO3GGX. Guaranteed 100%.

It’s very easy to connect and use. It doesn’t required knowledge other than how to connect a regular Bluetooth device.

Just plug my HC-05 module into your TRX and run the application on your phone. Connect via Bluetooth. Done.
– Change Bands
– Tune Frequency
– Change Modes
– Transmit (PTT)blu1blu2

High reliability, quality and strong support.

Just read this:

This Bluetooth CAT interface works GREAT and is EASY to setup! (FT897D)
well assembled component, excellent service
Great! Thank you, work very fine!
A+++++ Quick shipped, good service

How it works?
It works as any other Bluetooth devices in your room. Like a cellphone. Turn On. Pair. Connect. Ready. Sounds simple! Oh yes, trust me you wouldn’t believe how it simple.
Look at the picture. Just want to show an example for FT-857D (have done many CAT adapters for this rig)

What we can use it for?
In same way as you use the standard CAT cable. To control your transceiver (frequency, modes and also PTT). Imagine, no cables, no web on your desk, just rig and computer.
What transceivers are compatible?
Any with CAT connector. Simply you have to use the correct plug for your rig (8 Pin mini DIN for Yaesu, 3.5 mm Stereo CI-V for Icom and etc)
What do you need to make it?
Some components, soldering iron, magnifying glass, tools, wires and patience.
What components do we need?
– Bluetooth Module (HC-05 or similar)
– Voltage Regulator 3.3 V LP2950 (or any with out 3.3 v and in 5-20 V)
– 4 resistors 1 kOhms 1/125 W
– 2 capacitors 0.22 uF, 25V
– Dual Ultralight LED
– Connector which will be plugs to your rig
– Some box or case for module
Where we can buy parts?
Anywhere. Local radio components store (radioshack or etc), online store (digikey, mouser), eBay. The Bluetooth module sells on eBay and average price is $5.
There is not a big difference between modules but I recommend use or HC-05 or HC-80. They were tested by me in my projects. Other parts are not critical.
How the module looks and pin out?

HC-80 Bluetooth Module (difference with HC-05 only with one pin for LED. I will talk about that later)
HC-80 Bluetooth Module
Now let take a look at schematic and module connections:
As you can see there is HC-80 module on the picture. For HC-05 module the LED (Paring) should be connected to PIN 32.

To make it easy I uploaded a datasheets:
download HC-05 (in PDF)
download HC-80 (in PDF)

Also I guess you noticed that I use triple color LED. It’s really up to you and TX indication just an option. Realistically you need only POWER and BLUETOOTH Connection indications.
Basically you need to solder some component on top of the board. I usually solder 3.3v regulator first along with 0.22 uF 0805 size SMD capacitors and then LED on other side of the board.
Be careful when you solder and avoid the overheating. The board as you noticed very small and you have to hold it when solder. 1 kOhms resistors are soldered straight to the pins TX and RX.
Before solder to the connector you have to check the board and all connections. Use a small power supply. Apply 12 v to the input of voltage regulator. Power ON LED should light on and Pairing should blinking. That means everything works as should. Of course you can check the Bluetooth connection. Just follow the steps which you can find below.
When everything is tested and ready to use now time put all together. I don’t know what box or case would you use but I want to show my idea. I used the simple plastic case of 10 Pin DIN plug. The 8 Pin mini DIN slides in to 10 Pin mini DIN plastic cover. Simple, easy and looks neat. Take a look.




Certainly there is no standards and all depends on you and your imagination. Use whatever you have and whatever you like. Just remember some important things:
– It’s a wireless device so the case suppose to be plastic (NON METALLIC)
– No metals around PCB antenna (otherwise it’ll reduce the distance)
All right it looks like you made it and now time to do a final check.
How to Connect it?
Before Use:
Make sure that your laptop or PC has Bluetooth Adapter otherwise it will NOT work.
1) Turn Off transceiver
2) Plug in HC-05 into CAT/Linear Connector
3) Set in transceiver Menu – CAT
4) Search for new Bluetooth devices
5) Click to PAIR (passcode 1234)
6) Make sure that HC-05 is connected to PC
7) Check for assigned COM port (example COM12 or COM9)
If you don’t know how:
Right click on “My Computer” icon -> Click on “Manage” ->Click on “Device Manager” -> Click on “Ports(COM&LPT) -> Verify the assigned to HC-05 COM port.
8) Change COM port in your program (HRD or etc) to that COM Port
9) Check if all work as should.
10) Got a problem with communication or connection feel free to contact me.

Default settings for HC-05 Bluetooth Module (verify it in COM Properties).


The Technical Data:

The Technical Data:


Alex K6VHF