Author: G6WRB (Page 1 of 2)

ISS SSTV

15 October, 2024 / G6WRB / 0 Comments

I’ve dabbled with Slow Scan before, but it’s not something that’s ever really captured my imagination.

However, when I saw that the ISS was going to be transmitting SSTV round the clock for seven days, as part of an experiment in conjunction with ARISS, it piqued my interest… almost anything to do with the ISS tends to make me sit up and take notice.

And so, armed with the latest orbital information from Heavens Above and a visual representation of the station’s position from N2YO, I set about trying to successfully capture some images from the ISS.

The option with the least amount of kerfuffle was to connect my SDRPlay to my X-200 colinear and then install a Virtual Audio Cable to feed the output from SDRUno into an SSTV decoder… RX-SSTV is my preferred piece of software for this task, as I have no desire to ever transmit SSTV.

OK, setting up the VAC was a little troublesome but I got there.

Actually decoding the images proved to be far less successful, with lots of noise giving me only partially decoded images.

On the umpteenth attempt though, I set everything up and just left it running whilst I took the dog out, fully expecting yet another only semi-successful attempt. Upon my return though, I was rewarded with the following image: 100% copy!

The ISS was passing over Germany when this image was received. If I have my Pythagoras right, that’s a distance of about 450 miles.

As someone pointed out to me, it is – of course – Line Of Sight, but even so, I think that’s not bad for 2m FM into a white stick on the side of the house!

And I did pick it up briefly, loud and clear for just a few seconds, as it passed over Budapest yesterday. Pythagoras tells me that’s about 960 miles!

As requested by ARISS, I submitted my image to them and I was rewarded with my first ever Amateur Radio Award – that’s it in the pic at the top.

Slow Scan still hasn’t captured my imagination, but it was a bit of fun.

Kenwood TM-V71A motorboating

21 December, 2023 / G6WRB / 0 Comments

I’ve been getting some complaints recently, about the audio from my Kenwood TM-V71A that I use in the car.

It has developed a ‘motorboating’ sound that sits at the back of my audio.

Strangely, it seems far more prevalent when I’m going through a repeater. No idea how that could be.

I had this problem a couple of years ago and a search on the internets showed that I wasn’t alone. Lots of people had the same issue with this rig. Research had shown that the culprit was the clock signal travelling between the microphone and the rig itself. That clock signal is needed for the keys on the mic to work.

A potential fix was to try re-crimping the RJ45 plugs on the mic cable. I tried this and sure enough, it worked.

But now the problem was back and I wanted a more permanent solution,

As I never use the keypad on the mic, the obvious solution was to just cut that clock pin. I have had the radio for about 8 years and have never used the keypad, but I know that as soon as I permanently disable it, I’ll need to use it for something.

And, so I decided a switch would be best, so I can disconnect or reconnect the clock wire as and when required.

Searching through my box of switches, I happened across a small tilt switch. I thought this would be a good idea, as the mic is in a vertical position when talking, but horizontal when keying something in. I drilled a small hole in the PCB to take the switch and wired it in: There are two circuit boards in the mic, with some wires going between them. The black wire is the clock wire, so I just cut that and lengthened it to reach the switch.

Turns out, it was a rubbish idea! The switch would activate at 45 degrees (of course!). Luckily, I had a very small slide switch, which fitted between the two boards quite easily. A small hole cut in the side of the mic casing and a dab of Superglue had it looking almost like it had been factory fitted. Almost.

Nonetheless, it does the job perfectly and my audio reports are “excellent” once more.

This Packet Racket

24 September, 2023 / G6WRB / 1 Comment

I’ve been playing around with packet, recently.

I’d read somewhere that it was beginning to make a bit of a comeback… I knew I’d hung on to that PK-88 TNC for a reason!

I connected it up to a little Yaesu 270R and had a play. It was only then that I realised just how much I’d forgotten. I used to be all over packet back in the day, but now I could barely remember any of the commands. But, with the help of the manual and some advice from a mate and a local amateur, it’s getting there.

I can connect to my mate’s node with little problem and also the one in Milton Keynes. I couls also easily connect to the node at the old MI6 place out near Aylesbury, but it seems to have gone off-air recently.

And I’ve got my mailbox set up again. It was quite an exciting feeling to come into the shack the other morning and see the mailbox light flashing, indicating that there was a message waiting for me. That LED hasn’t flashed in 30 years!

I’m using the PC to talk to the TNC at the moment, via PuTTY (a terminal emulator program) and I have now configired it with green text to give it that old dumb terminal retro look. For some reason, I’m loving it even more now!

I’m having a few connection issues though. Reducing the packet size from 128bit to 64bit seems to have helped and also increasing the tx delay by 100ms. But I think a serious issue is a lack of audio level from the 270… something I’ll need to take a look at.

But, at the moment, I’m just having a lot fun playing with – and re-learning – some AX.25 stuff again.

Adapting

27 September, 2021 / G6WRB / 0 Comments

Back in 2013, I fitted a new Diamond X-50 colinear on the side of the house. A 12 metre length of UR67 coax connected it to the radio.

Now, the X-50 came fitted with an N-Type socket and when I mentioned at the local emporium that I’d never made up an N-Type before, I was advised that they were a bit fiddly and it would be easier to use an N-Type to SO239 adaptor.

So I did.

It all worked really well and was certainly an improvement over the Slim Jim I’d had years before.

But over the years, I noticed a drop in performance. GB3HR, which I had been able to get into with little problem, slowly slipped into the noise and eventually became unreadable with me. At first, I thought this was due to the repeater owners reducing selectivity, to try and prevent the troll that sits on there from getting access. But then I noticed other issues.

Eventually (two weeks ago), I decided to replace the X-50 with an X-200, giving slightly more gain, and also replace the UR67 with some Ultraflex10 – again providing slightly less loss.

The difference has been tremendous! So much better than I had estimated with the 2dB gain I’d calculated.

So, I looked at the X-50, to see if I could see any reason why it had been under-performing and I noticed that the aforementioned adaptor was at fault. Whilst it looked clean and to be in good nick, the petals on the SO239 part must have shrunk slightly, as when I undid the PL259 connector from it, the weight of just one metre of RU67 cable was enough for the plug to slip out of the adaptor. It looked perfect, but was really loose fitting. I have tried other PL259 plugs and they all fall out, just the same.

So, I’m guessing the adaptor was the cause of this underperformance, all along.

The new aerial doesn’t have an adaptor, as I fitted an N-Type directly to the cable: yes, it’s a bit fiddly, but really not that difficult, it turns out.

And now I know how to do them, I’ll be fitting them on all my VHF/UHF cables.

And I’ll definitely not be using any adaptors again!

Out & About

30 August, 2021 / G6WRB / 0 Comments

Today I went to St Neots, in Cambridgeshire.

And wandered around a damp field.

Full of damp men.

Looking at a load of old, damp, radio-related tat.

And had a great time… as did we all, I think.

It’s the first radio rally I have been to in nearly two years and it was good to catch up with some like-minded nerds, who I haven’t seen in a while.

And I grabbed a couple of bargains too, which pleased me greatly.

It looks like the rally calendar is starting to get back to normal.

Hopefully, the next one will be just as enjoyable.

And not as damp.

Dead Handy

17 March, 2021 / G6WRB / 0 Comments

My Wouxon KG-UV8D stopped working the other day.

Two thoughts crossed my mind simultaneously:

“Oh bugger, I suppose I’ll have to spend out on a new handheld now”.

“Yay! I can go shopping for a new handheld now”.

Still, being the curious radio amateur that I am, I decided to see if it was fixable.

A quick investigation showed the battery had run out of charge, despite it sitting in the charger for the previous 24 hours. Hmmm. I checked the charger, and sure enough, there was no voltage on the terminals.

I was somewhat dismayed when I opened up the charger and could see nothing immediately obvious. Also, it was nearly all SMD… all too small and fiddly for my liking – I like proper components that you can actually pick up with your fingers.

Also also, I couldn’t find a schematic for it.

But, I started tracing voltages through anyway and it wasn’t long before I found a component with volts and one side and nada on the other. Either a diode or a blown resistor, maybe. It had no values shown on it, just the letter H. A bit of research on the internets and some conversations with some fellow hams suggested it was most likely a 1A fuse. Bridging it with a piece of wire proved that to be the most likely case as the charger started working properly.

I didn’t want to leave the fuse bridged out – fuses are there for a reason after all – but a replacement SMD fuse on ebay was about four quid. Yes, four quid! For a fuse!

So, I used a 20mm cartridge fuse of the right value, slipped some heatshrink over it and wired that in instead.

Put it all back together and it works a treat. No need to buy a new one.

Whilst trying to find a schematic on the internet, I read of many instances where this charger has failed, so I thought I’d write it up here for anyone who might have a similar issue.

What a packet

10 February, 2021 / G6WRB / 0 Comments

Whilst rummaging about up in the loft the other day, looking for… I can’t remember what, I stumbled upon my old AEA PK-88 Packet TNC.

You remember them, right?

All the big boys were running PK-232 units, but they were too costly for me. The cheaperPK-88 served it’s purpose well, though.

Back in the late 80’s, I’d gotten very interested in the X.25 protocol used to send data packets around a telecoms network and so, when some bright spark developed a version that could be used in amateur radio in the early 90’s – AX.25 – I of course decided to get involved.

Back then, packet communications was all the rage and hundreds of us set up nodes and digipeaters at home, forming a radio mesh that allowed packets to travel up and down the country, in much the same way as companies like BT were doing. Our packets tended to be just routine messages (like an email), rather than the commercial data that travelled over X.25. Of course, our amateur network lacked the millions of pounds that the telecoms companies were able to pour into it: it was slower and prone to failure… but it was fun and we learnt a lot about network routing. Looking back at it now, I realise just how much I have forgotten, over the years.

But anyway… amateur packet was pretty much killed off by the internet and so I wondered what I could use my old TNC for.

Not much, according to Google.

But, a version of amateur packet is still alive, in the form of the Automatic Packet Reporting System. Unlike the old system, APRS tends to be more localised, with guys broadcasting beacons, detailing local weather and shit like that. All a bit pointless, but I wondered whether I would be able to use my ancient TNC to pick up APRS packets and decode them.

And so, after much fiddling about with RS232 cables and PuTTY and a bit of soldering, I was rewarded with the picture on the right. Success!!

I am pretty chuffed at having figured out how to get it to decode the packets, after nearly thirty years.

Next step is to see if I can actually transmit any.

Watch this space… if you can be arsed.

Project Phoenix

17 March, 2020 / G6WRB / 0 Comments

I was gifted a lovely little radio a while back – a Yaesu FT-270R.

It’s an old 2m model, dating back to the late eighties, I’m guessing. As such, it lacks CTCSS capability, which limits its use somewhat.

However, there is a space inside to fit a FTS-8 subtone encoder board. And so I thought I’d fit one of these and give it a new lease of life.

Sadly though, the FTS-8 board is no longer available and secondhand ones command a hefty price tag.

What to do? Well, make one of course!

I found an elegant design on the web and built it onto a piece of veroboard. Plugging it into the radio, changed some of the available functions, so the radio obviously detected the board.

It allowed me to choose the subtone from the front panel. Excellent.

But it didn’t work. Checking the output with my scope, the tone just wasn’t there… or rather, it wasn’t what it should have been.

I spent ages fiddling with it, but ultimately could find nothing wrong.

And so I passed it onto Dave, who – being a clever bugger – worked out pretty quickly that the board I had built actually worked perfectly. Unfortunately, the radio didn’t. It was giving out the wrong signals to the board.

This wasn’t something that could be easily fixed – possibly a microprocessor issue. And so, I figured a workaround, that would allow the tone to be selected manually, using a combination of switches to produce the binary equivalent of the hexadecimal value that the board was looking for in the tone lookup table.

This worked perfectly and when I tested it, I was successfully able to open several different repeaters, all using different subtones.

And then I found a bug, where the tone would only change after five minutes and not whenever the PTT was keyed. This looked to be a fault with the MCLR on the PIC… possibly damaged by putting in 7.6 volts from the radio (datasheet states that Vpp shouldn’t exceed Vcc). Not having another chip available, I made a slight mod and fitted a miniature relay, which only allowed the board to be powered when the PTT was depressed. This seemed to work nicely and I was able to switch tones easily and on-the-fly.

So, I put a call out on a repeater. “Your audio is awful!”, I was told. I replaced the mic ( a new one from ebay cost fifty quid! Yes, fifty quid for a 30 yr old mic!) with an old YM-47 from an FT-290 and it worked perfectly… once I had figured out the differing wiring scheme.

And so, after many weeks of working on it, on and off, it is ready to be put to use.

Not that I need another radio at the moment, so a friend is going to borrow it.

Many times I nearly gave up on it and was going to throw it away. But, I had invested a lot of time and a reasonable amount of money on it and so I wanted to see it through.

I’m pleased that it is finally finished and working… because that means I can now move onto my next project 🙂

I officially give up! Yet again.

23 June, 2019 / G6WRB / 0 Comments

Morse code is an anachronism.

Invented and used in the 1840’s, it seems somewhat out of place in today’s high-speed world, where data rates are so high that whole sentences of text can be sent in the blink of an eye.

It’s an outmoded form of communication, that just doesn’t sit well with modern methods.

And yet… it does.

It is still used by the military – not necessarily as the main basis of contact nowadays, but certainly as a fallback, I’m sure.

And in the world of Amateur Radio, it is still a much sought-after skill amongst many.

There are plenty of amateurs out there who can do Morse. Many of them excel at it. And there are even some that won’t use any other method to communicate over the air.

Sadly, I’m not one of them.

I would LOVE to be able to read morse code, properly. I can send at slow speeds and I can read it at very slow speeds. Very slow. Very, very slow. Reading is the hard part.

Rather like learning a new language (and ostensibly, that’s what it is), there are many different methods for learning it. Over the years I have tried reading books (Duh!); listening to tapes and listening to other operators sending. I have tried several PC programs and mobile phone apps. I have built machines for practicing with (see picture above), eventually taking them apart and using the bits for another project, because I was getting nowhere.

Frustratingly, in my teens, I did learn how to read and send, and could do so at about five or six words a minute. If only I’d kept it up.

Similarly, I used to be able to parlez francais to a reasonable degree.

But I allowed them both to lapse and nowadays I struggle to learn either.

And it really annoys me.

I’ll admit that this is partially down to commitment. I don’t seem to have the time nowadays to study for such things.

And the inclination. That’s kind of gone too: I want to learn it, but I don’t want to put in the effort. Like the rest of the MTV generation (yes, I think I just about fall into that category) and, as Freddie Mercury sang: “I want it all and I want it now”.

And so, after several months of “giving it another go”, I have hung up my headphones.

Again.

For the last time.

That’s it! I have resigned myself to the fact that morse code will forever evade me.

No more, will I try learning and decyphering that strange sound of dits and dahs pouring from my radio speaker.

No more, will I spend hours in the car listening to an 800Hz tone beeping out letters of the alphabet to me.

No more will I drive the family mad, as I sit in my room badly tapping away at a morse key.

No more, will I… who am I kidding? Give it three months and I’ll be back at it for another half-hearted attempt.

Dah-di-dah

6 October, 2018 / G6WRB / 0 Comments

This morning, I visited the National Radio Centre in Bletchley Park.

It was this: most excellent!

By chance, I’d happened to pick a day when an event to celebrate the breaking of the Enigma code was taking place.

An Amateur Radio station in Italy, was broadcasting messages in Morse code, that had been encrypted with the Enigma cipher and various stations around the world were trying to pick up these signals and decrypt them. I – along with many others – watched with interest as the amateur radio operators received and decoded the Morse code, writing the 5-character blocks onto a replica form to that which was used in Bletchley Park during WW2.

This was then handed to another chap, who was giving a superb presentation on the workings of a genuine Enigma machine that sat on a table before him. His audience was enthralled as he decoded the message letter by letter.

Afterwards, I took a quick walk around the mansion house. It had changed a lot since I last visited it back in the eighties, when I worked for BT. Back then, we used it mainly for recreation, as I remember, but it has now been restored to it’s former glory. The picture above shows one of the downstairs rooms which – when we used to go there and if memory serves me correctly – housed a pool table. It now – as you can see – gives an accurate depiction of what it would have looked like in the 1940s.

All too soon, my time ran out and I had to leave.

But I’ll go back again soon.