Isolated sound card interface

I've been working towards getting my girlfriends HF rig remotely controlled. We have it installed in the sun room at the back of the house but her office is up in the attic on the 3rd floor.  This presents a problem as not only do we need to control the radio but we also need to hear what it receives and also send it some audio to transmit.

The radio control is easily achieved by using Ham Radio Deluxe and is very well documented elsewhere. For the audio portion I am using RemAud by DF3CB which is also very well documented on his website. What's not so well documented is the hardware that one might need be able to both receive and transmit audio from another location. It should be noted that whilst I am doing this from another room 3 floors away it could equally be done from 3000 miles away over the Internet.

If you are familiar with Skype then you'll know that it uses the sound system installed into your PC. The microphone is usually sourced from your webcam and the speakers let you hear the other person. RemAud is a similar application. It uses the same audio sources. And that's where the difficulty begins. Your HF rig cannot use the mic on your webcam.

Luckily this problem has been solved many times before. A simple radio-computer sound interface is all that's needed on the radio end. It needs to move audio from the PC to the radio and back. It also needs to key the PTT to enable the radio's transmitter. This is what I came up with.

It's an isolated audio interface with USB based PTT keying. I made it from the junk box. The Audio part is a copy of the many transformer based sound card interfaces one can find on the 'net. The transformers isolate the electrical path between the radio and the computer in an effort to reduce computer noise getting into the radio.

The USB part is a USB to serial interface that I had meant to use in an Arduino project but never got around to it. I added a small bit of circuitry to invert the signal from controller chip and also isolate the PTT from the computer.

I also added a USB sound card adapter to the PC to manage the sound instead of using its built in sound facilities. I'll be moving it all to the rear sockets of the PC and there are no sound outputs there.

It works very well. However, I am not happy with it. The PTT should really be isolated via a opto-isolator and it's larger than I'd like. So I set about designing another interface. This time it's more compact and has "proper" sockets etc. It's also fully isolated and can also key some CW too.

I designed a board for it too. You can get it at Oshpark

And here's the finished result. It works perfectly. It's also much smaller and now fully isolated. I used a PS/2 male-male extension cable that I got from Microcenter to connect the data port on the rig to the interface. At $8 it was not worth my time or effort to try soldering a cable myself.

There was a caveat that took me a few days to work out. Direct from the factory the FT232 USB-serial chip has its signals inverted. This is correct as it actually converts from TTL to USB, expecting another chip to do level shifting up to the +/-12v that is RS232. But the chip makers have thought of that. They have a tool on their drivers website that allows you to change the signalling on any of the pins. I inverted DTR and RTS so that they would go high when applied thus powering the LED in the opto-isolator. 

The Bill Of Materials is quite trivial;

• FTDI FT232RL USB to Serial chip x1
• 10K x1
• 1K x3
• 3MM LED x1
• 0.1uf x2
• 10uF x1
• Mini-USB 'B' x1
• 4N25 x2
• 3.5mm audio socket x3
• 42TM016 600:600 audio transformer x2
• PS/2 6 pin mini DIN socket x1

Remote control of your radio via "CAT"

I've moved into a new house. The only room in the house conducive to radio is a conservatory or sun room at the back of the house. But It's not ideal for all the trappings of ham radio and so I looked into some sort of remote control over my house data LAN from my study in the attic.

I'm not going to document here what I did but I used Ham Radio Deluxe on a small footprint Windows PC and was able to remotely control it with HRD installed on my Linux box. It all works like a dream. It uses something called CAT or Computer Aided Transceiver which is just a fancy way of saying that the computer can control the radio.

Well, works like a dream might be a bit of a stretch. It _was_ working like a dream. Then suddenly it stopped working. So I descend the 3 floors down to the sun room only to discover that the radio was being controlled by a different sort of CAT.

Meet Elvis. He likes to sit on electronics. I assume it's because they get warm?

Folding Solar Panel

I own a 120W solar panel which is great for recharging my batteries when I'm camping and doing outdoor radio activities. The problem with it is that it's too big. I cannot get it into my car easily. So the obvious thing would be to get a smaller panel. OK, but smaller means less power and oddly, they are more expensive than larger ones when converted to "$$ per Watt".

The obvious solution was to buy a folding solar panel. It would deliver the power I want and also fit into the car. However, have you looked at the price of folding panels? They run about 3 times the price of a non-folding one at the same power output. No thanks.

So what to do? How about I build my own!

So that's what I did. I was able to source some 40W panels from Amazon for $55 each including shipping. A continuous or "piano" hinge, a pair of sash window locks and a handle were all that was needed to complete this project.

Here we see the back side of the panels. I used the hinge as a template to drill holes for the rivets I used to secure the hinge to the panel. Once the hinge was installed it was on to the wiring. The panels had a nice box on the back where the connections were made. Opening the box revealed 2 screw terminals. It was a simple job to add a pair of ring terminals to one of the wires and connect it to the other panel's junction box.

So what was the point of making this? Look at the picture below. This is me and my telescope equipment. I took my family to see the Great American Solar Eclipse (August 21st 2017). Powering their devices and all of my telescope gear, laptops etc took quite a bit of power. I was able to do this by using a large deep cycle marine battery and this solar panel (and the relevant charge controllers etc). Look closely just below the bottom left corner of the black box housing the laptop. You can see the panel on the ground.

Solar powered GMRS repeater

I recently made a solar powered GMRS repeater for use on a remote farm. The largest building on the property is the barn and so this was chosen as the home for the machine.

So this is the almost finished repeater mounted onto the wall of the barn. There are still a few jobs to complete such as running the antenna coax and mounting the solar panel outside. We ran out of time before the summer storms came and we had to go home. Luckily we'll be back there shortly so can finish it up.

It's a simple setup consisting of 2 UHF Motorola SM50's, a "mobile" cavity filter, Raspberry Pi 3 running SVXLink repeater software, solar charge controller, 35 Amp lawn mower battery and various wires and connectors. Oh, and a solar panel and antenna. Total cost for this machine was about $325.

ACME fails again ...

Here in the DE/MD/NJ/NY/PA area of the US we have a supermarket chain called ACME. I swear to Bob that it is run by idiots!

I spotted this in my local store recently.

It's a recall notice. It tells of a product recall for a chicken nugget food item. But look behind it on the shelf (click the pic to enlarge). It's the very same item that has been recalled!!!!

3D printed Anderson Powerpole distribution box

I have a Robo3D 3D printer which I'm having a lot of fun with. I'm also trying to build a GMRS repeater for use on a farm. I laid out all the hardware only to discover that I needed a tidy way to distribute the power to the various devices.

The repeater being laid out on a 2'x2' piece of 3/4 plywood

Meet the Parametric PowerPole Breakout Box which can be found here on Thingiverse. The Parametric part comes from the way in which you can create anything from a 2 port to an 8 port box.

I printed a 4 port box. As you can see, it has 6 ports. No my printer did not do it wrong. The ports at either end allow the power to be connected to the box without loosing one of the 4 ports. One can also stack the box together to make larger boxes. In the above pictures I've assembled the connectors the wrong way - DOH. Luckily I caught it before I soldered it all together.

That is #12 solid electric wire connecting the PowerPoles together. I pulled the ground wire from a small run of Romex household electrical wire and used it to connect things together. The joins were wrapped and soldered and the ends were crimped and soldered.

Depending where you get them from PowerPoles can be as much as $2 a pair so using that price as a guide (I buy mine in bulk and have them on hand) I managed to construct this box for about $15 including the price of the PLA 3D printer material, electricity etc. Not too shabby!!

Schrodinger's Cats?

What is it about cats and boxes. Every time you put an empty box down onto the floor it becomes immediately inhabited by a cat. Or does it? 😉 Perhaps this was what captured Schrodinger's imagination and shaped his ideas on Quantum Physics?

For the cat lovers out there, here is a collection of just a few of the cats that inhabit my apartment. Please understand that they are not _my_ cats. Indeed, one of the cats has another cat as his pet.

Elvis

Gracie

Boots AKA Orange Dog

Gracie

For his next trick, Boots will make a girl disappear

Rascal. He's a Lhasa Apso with a Doberman complex. The cats are bigger than him.