Linux No More

I tried and I tried. I tried to use Linux for my shack PC for ages, and it was always a battle. Sure, more often then not I got there, but a lot of time was wasted messing with computers rather than radios.

Further, there was a few cases where the software I wanted was Windows only. Sure, numerous software I could run under WINE, however there were some I could not. And in the end, I actually found that of all the HAM software I used, only one was a native Linux app (Fldigi) but even it has a Windows version. But the straw that broke the camel's back, was attempting to get software going so that I could use my SoftRock. The normal candidates are all Windows based, and I was having little luck with the Linux options (or indeed, lack there of). But in this case, the Windows offerings were not running under WINE, so I had nothing at all.

So, my shack PC is now Windows XP – linux no more. And I must say, it was wonderful to set it up. In under one day I had XP install, all drivers installed, virus scanner installed and all my HAM software installed (and a few more). Further, I plugged it in and it worked.

Further, it's always appeared that the majority of HAM software is Windows based, so it's great to know I now have access to so many options (even things as simple as contest logging software). Excellent!

It all comes down to the right tool for the job at the end of the day, and I think for HAMing about Windows is the way – as ham software seems to be predominantly Windows.

(Oh, there was one other native linux app, as I was compiling WSPR from the latest source. But, I'm happy to use 2.11 pre-compiled if it makes HAM life more radio focused as a whole.)

SoftRock Complete and Working

Well, I've completed my SoftRock Lite II for 40m. It may have taken me some six months to start building it, but it was pretty straight forward in the end. A couple of hours a night for a couple of nights and all was done. It was my first time doing SMD components, and I was surprised at the success I had. No need for all the procrastination. It's also the first receiver and the first amateur radio kit I've built – well, aside from a crystal radio kit. 😉

Looking forward to playing with it more, but so far I've been impressed with the reception it's achieving (but VK and DX). I'm hoping eventually to set it up with WSPR and see how that works.

Enjoy the pics.

Softrock004Softrock003Softrock002Softrock001

Small Magnetic Loops

Of the various types of antennas I've built, I've never built a magnetic loop. It always seems like there's a bit of magic involved and relies on hard to get suitable air spaced variable capacitors.

By magic I mean people rarely give exact dimensions; and to find a suitable air spaced variable capacitor is not just a case of going to one of your regular electronic parts suppliers. However, I've seen VK3YE play with magnetic loops a bit lately and I know they're good for their small size, so I think it's time. Better yet, I believe they match a need I have.

This week-end I finally got around to starting to build my Softrock Lite II kit I purchased back in (I think) March – when I was still in F call (so RX only was the only sensible option from a license perspective). Seeing it's RX only (and due to thinking my shack computer may not have a stereo line in) I'm thinking it could be cool to just setup inside on my main machine. For that though, I need a nice simple antenna that I could have inside and thereby needs to be relatively small. (Oh, and I'm going for 40m.)

In my search for small magnetic loops I came across the G4ILO Wonder Loop. This is close to what I need, and could be fun to build and then use with my FT-817. Further, I also like the simple SWR bridge that is being used – may just build one up from scratch.

I like the way he explains figuring out the dimensions (and indeed the information that it's a simple 5:1 ratio between the loops), and I've also found an Australian supplier of variable capacitors. It's the local Jackson Brothers suppliers that have been advertising in AR Magazine for years but their website never worked so I left it there. But I finally took a punt and emailed them to see if they had a catalogue and price list. Turns out they do and were very prompt in it getting it to me.

So now I have a known supplier of high quality variable capacitors, an idea about dimensions for magnetic loops, and a need. All I need now is time! 🙂

2200m Oscillator PCB Version

Thanks to Dale (VK1DSH) I now have a PCB version of my oscillator. Further, thanks to his input it also now has a few additional items to the circuit. It has a diode on the +ve supply input to protect against reverse polarity, etc. as well as better use of capacitors for the voltage regulator and to provide better bypassing.

I just built up the PCB and found the resulting waveform much cleaner as a result. Very nice.

Just out of curiosity, although I had it running on the table inside I went out to the shack to see if it's very small signal was being picked up by my grabber. Indeed it was – pleasant surprise (capture attached). Also seems to show that my grabber freq read-out is inline with my 'scope.

A big thanks goes out to Dale for his input and doing up a PCB for me – something I'm still to try my hand at (I've some photosensitive PCB material, but that's it).

Vk1is_2200m_osc_-_pcb-001Grabber-0150Newfile1_-_pcb

More on 2200m Oscillator

Last night I had a bit more of a play with my osciallator. I wanted to look at a few things:

  • The RF on the supply rail;
  • The use of an Rd capacitor in the oscillator circuit; and
  • Stability.

For RF on the supply rail I was reminded by both Dale (VK1DSH) and Dimitris (VK1SV) about the use of a bypass capacitor on the Vcc pins for ICs. I say reminded as I remember reading about these when I was playing with microcontrollers briefly, but had completely forgotten.

Being a best practice, I decided to follow suit and add them. So the slighly revised schematic is now – note C6 and C7:

Oscillator_schematic_-_rev_2

On the use of Rd in oscillator circuit, maybe it’d help if I first show what I’m talking about. In the below is a red box where often an Rd resistor is added:

Rd_loc

In the datasheet for the 74HC4060N they suggest trying a 2k2 resistor, but for my crystal this stopped oscillation. Indeed, testing last night showed 1k5 stopped oscillation and only once I went to 1k did it kick off. However, I found at 1k the waveform was a distorted sine wave and only once I got it down around 100R did things resume a reasonable sine wave. So in the end, I decided I’d do what many others before me have, and continue to leave it out.

But, an interesting exercise none the less, and first real good opportunity to play with my new resistance wheel.

Finally, I also wanted to see if this thing was stable. Not an overly detailed test, just something indicative. So, I hooked it up to the scope and ran it for just shy of two hours on the bench. In that time, the frequency counter on my ‘scope did not budge from 137.500kHz. So, at least to an accuracy of 1Hz I can say it seems pretty damn stable. 😉

Oscillator for 2200m

Recently I was frustrated with the amount of time it took to get some simple 2.205 MHz and 2.185 MHz crystals from Futurlec – in the end it took some 8 weeks to only get a small number of what I was after (and only with a bit of poking and prodding). This is not uncommon with Futurlec as you’ll find if you search the ‘net, but the thing is there are very few suppliers of such options and these were needed as I was trying to build something like the VK1SV MEPT transmitter for 2200m. Indeed, to build a crystal based oscillator for 2200m there are very few options, so that made it more frustrating.

Anyway, that frustration led to me to come up with a modified design myself. I saw on element14 that they had an abundance of 22MHz crystals and they’re known for rapid postage – and free at that. Suddenly, the idea seemed feasible for a 137.5 kHz oscillator based on 22MHz crystals – which I found more readily accessible. Only problem was, I only knew the basic idea of using 4000 series CMOS chips as dividers, so I had a lot to learn to do it myself.

Within time though, I’d come up with this design:

Oscillator_schematic

 

As you can see, it’s based primarily around three items:
  • 74HC4060N 14-stage binary ripple counter with internal oscillator
  • 74HC4017N decade counter
  • 22 MHz Crystal

The idea here is simple, the 74HC4060N first provides a 22 MHz Inverter Oscillator with the 22 MHz crystal. This is then used as it’s input for which we derive the ouput on the Q3 pin to achieve a divide by 16. This giving us a frequency of 1.375 MHz. This is then feed into the 74HC4017N so that we can further divide it by 10 which gives us the final frequency of 137.5 kHz. (A total operation of 22 MHz divided by 160.)

The only other bit of the circuit is the power supply. This is contoled with a 78L05 to provide 5V regulated as required by the 74HC chips. This should be noted, as these are not the plain CMOS chips (CD series) as these would not be able to work at the 22MHz clock frequency – normally only workable up to 12 MHz, but in some cases only 1 MHz. As a result, they require a Vcc of 2 to 6 volts.

Going back to the 22 MHz oscillator in the circuit, a couple of notes. The 4 ~ 40pf trimmer capacitor with the 100pF capacitor are to provide the required crystal load capacitance: CL = (C3 x C4) / (C3 + C4) + Cs. With those values – and using an arbitrary stray capacitance (Cs) of 5pF – it will cover a CL range of 8pF to 38pF – that should cover most crystals (mine required 18pF). Also of note in the inverter oscillator circuit is the missing Rd resistor (or Rs depending on your reference) to limit current to the crystal. With most circuits I see online this is ommited, but I think it could be interesting to try and figure out what this value shold be – as there are benefits. Initially I tried with 2k2 and that was far too large and meant no oscillation. But from calculations I guess you could try 75R, but I’m yet to experiment.

The other item to note is that I have observed there is a significant 22 MHz signal on the +ve rail (almost 1.5 Vpp). The above mentioned Rd resistor could help, but more so a decoupling network should ideally be added to the supply rail. Something I might consider if I have time to play with this circuit a bit more.

Anyway, even with these considerations this circuit works. Further, it also seems stable – although I’ve only run it for a few minutes and with no load. Oh, and don’t forget, the output from this is a square wave – so use appropriately. Here’s the output on my scope:

Scope_capture

All the parts you require can be fetched from element14, however if for some reason you struggle with acquiring the 22 MHz crystal there’s good news on that. Another reliable local supplier stocks them: Mini-Kits. And if needs be, I see that Futurlec have a 22 MHz can oscillator for just under $2.

Another option on the crystal front, is to consider using an 11 MHz crystal. But then the circuit is slightly different as you need to divide by 80. You could do this with two 74HC4017N chips (the first could divde by 8, the second by 10), however you’d also need to build the 22 MHz oscillator on it’s own to feed into it. But something to consider.

Anyway, here’s some photos from my resulting prototype:

Vk1is_2200m_osc-001Vk1is_2200m_osc-002Vk1is_2200m_osc-003Vk1is_2200m_osc-004Vk1is_2200m_osc-005Vk1is_2200m_osc-006

Finally, I’d like to send a thanks out to Dimitris (VK1SV). It was only a month or so back I had no idea about how you go about frequency division. I knew basically about frequency multipliers, but hadn’t even heard of frequency division. With his kind introduction to this theory I was able to produce the above and understand how it worked. Further, doing so also made me spend time to better understand inverter oscillators.

Thanks Dimitris! I may just get on 2200m one day soon.

 

 

 

Remembrance Day Contest

The week-end just past saw the running of the annual Remembrance Day Contest. I was only aware it was on a couple of days before hand, but decided I'd at least throw out a few calls from home.

Being only my second ever HF contest – my first being the QRP Hours contest earlier in the year – I wasn't really concerned about my result. I mainly just wanted to see what I could do on HF from home.

In then end, only 20 contacts were made with 100W, but all up I only spent a few hours playing, so that seemed pretty good – but pale in comparison to other stations getting well over 700!! But even by Saturday night after a couple of hours I'd already contacted VK2, VK3, VK4, VK5, VK6 and VK7 (no VK8 at all for the contest). I was surprised!! Not having done much on HF before, a few of those call areas were a first time!

Further, I had some other firsts. I successfully tuned up my random wire for 160m (which is MF, so that was nice) and made my first ever 160m contact with VK4HH. Additionally I also made a first time contact on 20m – actually in the end I made contacts on 160m, 80m, 40m and 20m (did try 15m and 10m but to no avail).

Anyway, it was good fun and next year I might try to plan ahead and make a dedicated attempt at it – maybe incorporating some CW!