Category: Wireless

Designing an even cheaper isolated digital interface for amateur radios

A few months ago, the ACMA made changes to the amateur LCD that allowed foundation class licensees to operate digital modes.

Excited to get into this in the new year, I begun looking into digital interfaces for the radios I already have. There’s many different ways this can be done, from as simple as not using a cable and relying on microphones and speakers, creating a straight through cable from the PC mic input to the radio speaker output and visa versa, to expensive isolated interface boards custom made in the USA.

I wanted an isolated board, because I have enough trouble with interference and noise in my apartment already, so the first two were out (although I did make a straight through cable for my Baofeng UV-5R for SSTV on 2m/70cm).

So I turned to the expensive isolated interfaces.

There’s plenty to choose from l, with different feature levels and prices! From the $230USD RigBlaster, the $200AUD SignalLink USB, and even the cheapest of the bunch, the Easy-Digi coming in at $30-50AUD shipped with slow shipping…

Naturally being a cheap ass I wasn’t overly satisfied with these options..

Luckily though, the Easy-Digi, saved the day! It’s such a simple design, with a published schematic, that it’s not too hard to roll your own with a few changes!

I jumped into EasyEDA and learnt how to do a basic schematic, then designed the interface circuit for audio using two 600:600ohm isolation transformers, and a PTT circuit using a DB9 rs232 connector because it’s easy, although I plan to replace that with a USB-C connector and a ch340 rs232 IC in a later revision!

I used components that I either already have laying around, or can get easily from JayCar for the most part.

The connectors and transformers I ordered from China at about $4-5 for 10pcs each.

With the layout done, I generated a PCB, and moved components around into a rough layout I was happy with, and hit the autoroute button :^)

I forgot to label the PC side connectors for the first revision, but I imagine there will be plenty of other changes I make anyway.

I uploaded the gerbers to JLCPCB to produce a test run of the PCB, which I should have within 2 weeks with the cheap shipping :^)

So if everything goes according to plan, I cluding parts and PCB manufacturing for 10 boards, I’ll have spend about $30-35 total, and I should be able to sell some of the boards to friends for $5-10 each offsetting my costs even more !

Yaesu FT-1500m restoration

A few years ago I picked up a Yaesu FT-1500m 50w VHF transceiver for a small amount, it was in pretty bad shape when I got it so it was pretty cheap.

I ordered a new microphone right away but because the previous owner super glued the old one in, I was never able to replace it.

I had trouble finding exactly the correct 6p6c Jack to replace the ruined one too.

I checked many places online, many stores in Singapore sim Lim, and many in Tokyo akihabara, until I finally found one that appeared to be close enough to use!

The new one wasn’t a perfect fit, I had to shave the corner of it down a bit, and drill out a small part of the radio housing to accommodate it, as it sits much more inside the radio than the stock one, but the pinout and height of the jack itself work ok. They’re logically correct too, despite being upside down compared to the stock.

I removed the stock Jack by carefully cutting away i at it with flush cutters until there was just pins left, then I desoldered those one by one, and cleaned up with some braid.

Installed the new jack, but it had plastic PCB mount rather than metal mounts I could solder. I decided to add some copper wire for a little bit of extra mechanical support. I added some liquid electrical tape to attach the wire to the jack.

After that was all done, I was more or less finished with what I can do!

I replaced the manky old M5 bolts with clean new ones, and will give the unit a general cleanup!

Unfortunately the rubber buttons are beginning to disintegrate, so I’ll have to figure out something to do there.. I cannot locate a replacement for those :/

The volume potentiometer has seen better days but still functions perfectly. But I may replace it in the near future.

Controlling an RS232 Device over UART / WiFi

I recently had the need to connect part of my AV setup to my Home Assistant instance, however to do so I had two options, using the LAN control option built into the device, or via an RS232 serial port.

Naturally I attempted to use the LAN control part first, which involves opening a TCP socket to port 10008 of the device.
But I ran into problems as the connection kept wanting a user to login, even though there was no user account, and I was unable to figure out how to pass the login prompt and send commands automatically.

So I went to JayCar and grabbed one of these:

https://www.aliexpress.com/item/32722395554.html

Basically, it converts a TTL level signal to RS232 level signals.
I hooked it up to a Wemos D1 Mini, on the ESP, you want to use one of the HARDWARE UART pins, so for me, I went with D4, which is GPIO2 / TXD1.

My equipment had a 3.5mm socket for RS232 control, the manual had a pinout for DB9 to 3.5 so that was a simple cable to make, but your equipment might have something else.

Code wise, this is what ive settled on using and has been working MOSTLY well:

esphome:
  name: sharptv
  platform: ESP8266
  board: d1_mini

wifi:
  ssid: '********'
  password: '********'

api:

# Enable logging
logger:

ota:

mqtt:
  broker: 172.16.0.60
  username: rs232
  password: ********

uart:
  baud_rate: 38400
  tx_pin: D4

switch:
  - platform: uart
    name: "Power On"
    data: [0x50, 0x4F, 0x57, 0x52, 0x20, 0x20, 0x20, 0x31, 0x0D, 0x0A]
    on_turn_on:
      then:
      - mqtt.publish:
          topic: esphome/rs232/sharp/state
          payload: "ON"
          retain: true

  - platform: uart
    name: "Power Off"
    data: [0x50, 0x4F, 0x57, 0x52, 0x20, 0x20, 0x20, 0x30, 0x0D, 0x0A]
    on_turn_on:
      then:
      - mqtt.publish:
          topic: esphome/rs232/sharp/state
          payload: "OFF"
          retain: true

  - platform: uart
    name: "HDMI 1"
    data: [0x49, 0x4E, 0x50, 0x53, 0x20, 0x20, 0x31, 0x30, 0x0D, 0x0A]
    on_turn_on:
      then:
      - mqtt.publish:
          topic: esphome/rs232/sharp/input
          payload: "HDMI1"
          retain: true

  - platform: uart
    name: "HDMI 2"
    data: [0x49, 0x4E, 0x50, 0x53, 0x20, 0x20, 0x31, 0x33, 0x0D, 0x0A]
    on_turn_on:
      then:
      - mqtt.publish:
          topic: esphome/rs232/sharp/input
          payload: "HDMI2"
          retain: true

  - platform: uart
    name: "HDMI 3"
    data: [0x49, 0x4E, 0x50, 0x53, 0x20, 0x20, 0x31, 0x38, 0x0D, 0x0A]
    on_turn_on:
      then:
      - mqtt.publish:
          topic: esphome/rs232/sharp/input
          payload: "HDMI3"
          retain: true

  - platform: uart
    name: "DISPLAYPORT"
    data: [0x49, 0x4E, 0x50, 0x53, 0x20, 0x20, 0x31, 0x34, 0x0D, 0x0A]
    on_turn_on:
      then:
      - mqtt.publish:
          topic: esphome/rs232/sharp/input
          payload: "DISPLAYPORT" 
          retain: true

I say mostly, because when the ESP reboots, it sticks some data out of the pin, which the equipment holds in its buffer. So if the ESP has just reboot, and I try and send a command, the unit wont respond, as it gets more data than it thought. 🙂

This can be fixed by including a line break and carriage return at the START of the command, to clear the buffer, or by sending the command twice. but i havent done that yet because i … havent got around to it… 

Ill also mention, the TX/RX might be wrong on the Chinese board because ive seen a few different photos, if it doesnt work on TX try RX :^)

Ive ordered a handful of these to test making it smaller (think a cable with a bulge in the middle)

https://www.aliexpress.com/item/32834977750.html


Yaesu FT-897D Battery Project

I decided to build a lithium battery for my Yaesu FT-897D because the official Yaesu Ni-Mh batteries are far too expensive to import here (Then you need the special charger too!)

At present when operating portable, I have been running a lithium battery external to the radio (often a higher voltage battery through a little power supply)

So I grabbed some battery packs made up of four 2200Mah 18650 cells each, three of these adds  up to 11.1v at 8.8Ah, this is plenty for my short trips !

I planned out how to fit them inside, and there’s more than plenty of space, see image 🙂

My preliminary notes were:

The three packs are each four 18650 cells in parallel

Totalling up to 8.8Ah per pack at 3.7v

At full charge it will be at 12.6v and at empty about 9-10v

I have measured how much power the radio draws, and on monitoring it draws around 8w, on transmitting around 18w (at 10w TX power, go figure) so that’s only 1-2 amps, super easy for these lithium batteries.

I’m just waiting for my BMS to arrive from China (battery management system)

As that has over current protection, over charge protection, over discharge protection and short circuit protection for the batteries

Then I’ll use some padded sticky foam to mount them in such a way they’ll get ventilation from the existing fans and good to go!

Gallery below! 

 

iPhone can finally read NFC tags!

Good morning!!

 

With the release of iOS 11 this morning, Apple has finally caught up with the NFC game and is allowing users to read NDEF formatted NFC tags !

They’re still a bit behind in that, you can only READ tags, not write them, and you have to specifically install an app to read them, the OS doesn’t natively support them.

However in my quick testing, for my implant, the read performance is excellent!

 

I can get a 100% hit rate and very fast responses.

 

Its very easy to locate where to hold the phone, as the antenna is the top back of the device.

 

 

Heres a video of it in action, notice how easy I hit the right spot ?

 

Ill do more tests as I can but as I don’t have an iPhone 7 or later device and for some reason the iPhone 6 apparently does not get NFC unlocked ?? it will be slow.

 

Im pretty impressed so far it will be good to see native support in the OS to allow Apple users to interact with the world just like us Android users have been able to for years!

Updating a Nortel 5520

Hello!

Almost exactly (give or take a few days) one year ago, I was browsing eBay looking at Nortel 5520 switches, I was upset that in America you could get them for $75US a pop, whereas over here they were almost $500AU each!

Fast forward to a few weeks ago, I learned of two Nortel 5520-48T-POE that were destined to go to an IT recycling company.
I was able to negotiate my hands on these two switches for $25AU each!

I got them home yesterday when I fired them up with my beautiful homemade serial cable (the one I got from Jaycar was crossover whereas the Nortel needs straight through)
I was greeted with an older version 5.0 software version!

This was no good, all versions of the software before 6.3.3 had terrible web interface.
I know many people say you should stick with the CLI, but when im in a hurry to make a change, check the status of a port, or shutdown / turn on ports, I want a simple and fast method of doing this.

So began the journey of upgrading the switch.

It started with an hour or two of research, trying to find firmware files, and documentation on the upgrade process and path.
You cannot skip major versions apparently, So I had to go from 5.0>5.1 and then to 6.3.

I was getting worried that all of the ftp servers I was finding referenced were dead links, until I stumbled upon a reddit users dropbox, which had everything I needed, PDF docs, firmware files for versions 5-6, I was set!

I found a page detailing the update procedure, which was a pretty simple command.

I reset the switch to factory settings, then gave it an IP address,

Then it was just a case of flashing the diag image, and then the main image.

A single command was all that was needed to flash each one:
5520-48T# download address 172.16.0.123 diag 55xx_diag.bin
5520-48T# download address 172.16.0.123 image 55xx_6.3.3.0s.img

These commands aren’t exact, but you get the idea.

After flashing each one the switch rebooted itself and did a pretty light show while flashing / booting.

Once the switch had rebooted, I checked the web interface by navigating to the switch IP address in Google Chrome, and was met with a warning that my browser may not support the page!
Dismissing the warning, the UI loaded, and it was far superior to the old one.
I suddenly have everything I need!

I will be installing this switch in my homelab once I can mod it to be silent, ill replace the fans with Noctua 40mm fans and see what else I can do for it.

WiFi speaker upgrade and Home Assistant TTS

A while ago I picked up a wi-fi enabled speaker from Target or Kmart for $50. It was advertised as on special for $80 down from $160, so I figured how bad could it be? Then when scanned in it came up as $50 so even better.

The speaker natively has Spotify connect and DLNA support, I don’t really have anything that streams to DLNA, so Spotify connect was what I had planned for it.
I did hope that I could get Home Assistant talking to it over DLNA but couldn’t find any DLNA components so wasn’t too confident on that.
The speaker itself feels well built, looks pretty decent, and sounds okay. It’s a bit bass heavy, and the PSU always sparks when you connect it (why is it 15v? Why not 12v???)
I used it for a day or two then it kind of got abandoned, as nice as a wifi speaker is, when it’s limited to just Spotify that’s less than amazing.
So fast forward a few weeks, I remembered that I have some Chromecast audio laying around doing nothing.
I had purchased them to test out the multiroom audio playback, something that has always interested me.

But after testing it out I didn’t really have a need for it.

I’m not walking around my apartment enough.

And the tv already has a regular Chromecast.
So the audios were just sitting on my modem in a triangle.
I grabbed one and hooked it up to the aux input on the wifi speaker to see how it sounds, and well, having the ability to stream content from almost any multimedia app, website or device is much more appealing than just Spotify.

Oh right I should mention that the speaker has a tendency to just, enter a sleeping state, where it disconnects from wifi, and doesn’t reconnect until you wake it up (I had to power cycle it ?)

This makes it REALLY annoying to use.
So I set out in a venture to install my Chromecast audio inside the wifi speaker,
What follows is a whole lot of work and overengineering that for the most part ended up being redundant.
I disassembled the wifi speaker and found that it does indeed have the rated speakers, and a fairly sized mainboard.

It had a wifi add on board too.

I left this in there so it will still function as its original purpose.

The plan was to disassemble the Chromecast audio, and solder wires between the aux port on the speaker and the Chromecast.

All the tests I did on this gave me faint audio on the right channel, and slightly louder audio on the right channel.

I couldn’t figure out why this was happening, as I traced all the connections and they were all correct ?

The only thing I can think of was maybe the wire is too high loss ?

Idk it was crappy hook Up wire.

Anyway I ended up just using the Chromecast short 3.5 cable. And melting a hole to plug it into the speaker.
For power I had to be a bit more creative, I wanted to run it off the existing power supply so it would be self contained.

A quick look at the main board of the speaker reveals a header with an i2c? Port on it. Including 3.3v VCC and GND!

I made a quick micro USB to wire lead and hooked up the Chromecast to the 3.3v line to see if that was enough to power it up.

Unfortunately it seems Chromecast needs more current than this port could give.

The Chromecast would power up then keep cycling between orange and white led, I think this is some sort of insufficient power indicator. Else it was just rebooting over and over haha.
Next I tried hooking up a 3.3v to 5v boost converter to see if it was just the low voltage causing the problem, but this has the same effect.

I concluded that this connector probably didn’t have enough current to power the Chromecast, which normally wants at least a good 5v 700-1000mAh of current.
I decided I would have to pull my power from the main +15v input, which obviously has to be stepped down.

So I grabbed a AMS1117 5V voltage regulator, which from memory the data sheet says can handle up to 12v (she’ll be right mate) and can output up to 1amp
Hooking this up between the 15v main input and and h Chromecast seemed to result in the same thing as before though …
It’s at this point I was wishing I had a nice big LM7805 or something.
I did however have an “adjustable voltage regulator module” from aliexpress, which was big and beefy. I wired this up to the 15v and then hooked up my multimeter to its output, it was showing 15v.

I turned it’s pot until it was a stable 5.02v which is close enough and then wired the micro USB to that.

Hooked up the Chromecast and it worked !!!

I shoved it all inside the speaker and reassembled it all.
With the speaker reassembled I gave it a test and all looked great!

Well worked great.
I remembered then, that Home Assistant had the ability to sent TTS to my TV Chromecast, I had disabled discovery of Chromecast because it kept showing up in the main view and nothing was using it,

I wondered if it could send TTS to the Chromecast audio??

So I re enabled discovery of Chromecast and restarted Home Assistant to see if it would pick it up. It did! And I had the option for TTS!

I did some setup stuff in Home Assistant that I didn’t document, but it was pretty straightforward!
Now I can send verbal notifications to the speaker’s by calling the tts service in home assistant, specifying the speaker media_player.wifi_speaker and giving it a message!

I also put another Chromecast Audio hooked up to a small Bluetooth speaker via a 3.5mm cable in the bathroom, so I can have notifications in there (this is also the only room with a sensor node at the moment!)

a notification in there could be: If the humidity reaches 100% and the window is detected as closed, verbally say ‘Please ensure window is opened to prevent mould build up’

or something like that.

 

Home Assistant is also able to message me via Facebook Messenger, which is handy for notifications away from home!
I might do another write up on Home Assistant another time though, once I fully understand it!

 

Thanks for reading 🙂

Some pictures follow:

ARNSW Trash and Treasure

This morning I went to the ARNSW Trash and Treasure event!

It’s pretty much a small hamfest!

This is the second time I’ve been to it, it was a bit smaller this time but there was still plenty of stuff. 

It was held at the ARNSW building in Dural

Antenna towers !

There was heaps of oscilloscopes this time, with many costing a mere $10-30!!

There was even this single channel scope with a GIANT display:



The first thing I spied when I was walking around was a small block of foam with 12 nixie tubes on it, it was sitting with a bunch of other vintage tubes. 

I’m a huge fan of nixie tubes so I went straight for my wallet to make sure they were safely mine! Haha
The list price was $120 but I talked it down to $60 for the lot. 

I also picked up a few random metal project boxes that… Seemed to be constructed into things. 

Only one of them was labelled so the other two were real mystery boxes !

Nobody was able to tell me what they were, but I see huge potential in rebuilding them into something else. 
I’m particularly fond of the one with the front handles!!

When I was home I opened up the two unknown ones to find them pretty much empty shells. 

The perfect playground for whatever I turn them into. 


I was also lucky enough to pick up some variable capacitors, which I’ve been chasing for a while. I don’t yet know the value of what I grabbed but it’s certainly closer to what I need than nothing !

I want to use it when building a magnetic loop HF antenna. 

I also picked up a rather nice dial with an easily configurable scale. You just cut out and slide it in. 

Overall it was a pretty successful morning ! 

I spent significantly less than I expected and came home with some pretty nice treasure!

Bonus picture:

Spot the long wire antenna:

Homemade FPV monitor

Hi guys, I wanted an fpv monitor that had a receiver built in. 
Looking around online there’s some for around $100ish but I already had a spare Sony LCD meant for a reversing camera, and a spare RC832 so I


 figured I would give it a shot !
I disassembled both first, and was pleased to find a little free space in the LCD. 

I positioned things around a bit and used a sharpie to Mark things out to get an idea of if this was feasible. 


It looked like it would work !

The cables it had were huge and thick and had multiple connectors and Yada Yada I didn’t want all that so I just soldered to the convenient break out connector !

I did some final position testing and drilled some holes for the buttons and antenna connector, also drilled a hole and filed it a bit for the LED display on the receiver to see which channel we are on. 

Hooked it up and tested everything before routing the power cable through a hole, the hole I drilled inadvertently had a connector right in front of it when ibsealed up the case, this conveniently served to compress the cable and provide strain relief!! (The connector was unused anyway!)

Everything sealed up and working !

Crude holes but meh they work !
It has a tripod screw hole in the bottom and that slot for mounting. I’ll sort something out to mount it later. 

It has the option to disable blue screen so I can always get as much image as possible even with low signal !

Runs off a 3s lipo. 

Not much room inside for anything else or I would have tried to fit something inside to power it…

Picture looks great ! It’s super bright so should be visible outdoors well enough. 

Das me

That’s all for now ! 

Radio Testing!

I went on a mission today to get my HF antenna working with my Uncle’s help!

We started out testing a ‘mini g5vr junior’ off ebay, it was about $50, and… not great.

Its only about 15m at its widest (both elements!)

We couldn’t even get it to tune on any band.

So back to the drawing board, or more the cutting board, we butchered the mini antenna and used its copper wire to repair the G5RV I already had!

With the two elements from the mini one soldered on, I was still about 40cm short of the correct length, so I cut 45cm of solid core ethernet, stripped the ends and twisted them together, and then soldered that in the mix!

with the two elements the correct lengths (or close enough)

we popped down the road to the park and strung the antenna between two trees about 50m apart from each other, using some rope to reach the trees.

The antenna was only 2-3 meters off the ground, so not ideal, but it was great hearing voices coming through the radio again!

It tunes on some bands, but not others.

I think im done messing around, and ill just buy a new G5RV and not let my parents near it (theyre the reason the one I have now is broken, they didnt even keep the half they snapped off :((((( so much copper just thrown away…)

The park is a good candidate, seems low noise there (compared to elsewhere, I still miss my perk in the mountains though!)

There is two trees with nice high branches I am eyeing off, about 10-15 meters off the ground, and ~70m apart.

If I can string it up between there, and set up camp in the middle of the two, with a little picnic table and some food, I think I could have a fun few hours!

Here is some pictures of the final setup, and a youtube video showing some sweet morse and voice coming through

Antenna Testing

https://www.youtube.com/watch?v=hTuyhu393Eg

73