Well, today I did some more work on the 2m linear.  Earlier this week I ordered some SMA connectors and some 1N5711 diodes for the project.

Two 1N5711 diodes will be used to make a voltage peak detector, to detect when the amplifier is subjected to power above 60mW.  The SMA connectors will be the interconnects between the modules.  This afternoon’s effort was spent soldering the SMA connectors onto two of the boards, and mounting the 2m amplifier module onto the heatsink.

The EME157B2 preamplifier kit was originally intended to be mounted in a masthead box, with BNC connectors soldered to the PCB, and stuck up a pole near the antenna.  In my application, I wanted it to be in the same enclosure (with suitable shielding) as the power amp, so that I could use its RF detection to automatically switch the power amplifier on.  I will also be using different relays, mounted on a separate board.

Instead of mounting the SPDT relays for the kit on the EME157B2 board, I’ve instead left these off.  I also omitted the 2N7000 MOSFET which turns on the relays, and L4, an RF-blocking choke which permits the preamp to run from a 12V source supplied up the coax.  I instead will power the preamp directly.

Since the relays will be on a separate board, the plan is to run wires from the gate and source connections where the 2N7000 belongs, and run those out to a controller board.  With the relays gone, the RF detection and the preamp are essentially two distinct circuits.  So 3 SMA connectors will be needed.  Here is the completed board with the SMA connectors fitted, and suitable jumpers installed, ready for tuning.

Completed 2m preamplifier. Connectors going left-to-right: Antenna input, Amplifier output, RF detector input.

Next, I finished off the power amplifier board, mounting it to the heatsink.  I have left one EMC filter disconnected for now, as the instructions say to power it up first with it disconnected to set the trim pot for 4.5V bias.  Rather than mounting the board flat on the heatsink, I have instead opted to mount the PCB at 90? to the module.  I had to make the supplied eyelets a fraction longer to accommodate this.  I also mounted SMA connectors on this board.

Completed 2m power amplifier. RF input is on the left.

The plan is, I’ll route RG195 coax on the left side to a small module which will contain the overload detection circuit and two SMAs for an external attenuator module.  On the right, a low-pass filter will be connected.  I also had a stab at tapping holes into the sides of the heatsink for mounting a bracket.  This bracket would hold the fans on top, and would bolt onto the main enclosure.  In doing this, I managed to bugger up two of the 8 holes, and thus what I’ll probably do, is buy a M4 tap tomorrow, drill them all out to 3mm and tap them to 4mm.  These are structural holes, so bigger is probably better anyway.

Much of today though was spent designing the controller.  I’m still finalising the design, but a rough schematic is below.

2m amplfier controller

So, not yet going, but big parts are built now.

Background

A few months back, I grabbed the trusty FT-290R II ready to do my weekly run from The Gap to Tarragindi.  Quick test to check everything’s okay… the power meter swings to full scale, but strange, I’m not hitting any repeaters.

Okay, grabbed the FT-897D instead, and I just did my weekly radio duties with that instead.  When I came home that evening, I had a closer look.  The FT-290R II was emitting a signal, the hand-held was picking that up.  It was also receiving just fine.  On a hunch I took off the FL-2025 linear, and hooked the antenna up directly to the radio.  Bingo… the radio works, the linear does not.

So, the linear had died, and thus I was in need of a new one.  Hand helds really don’t have much punch for mobile use, in fact, the FT-290 has been brilliant on the bike.  Not menu driven, so it’s real easy to drive while riding, simple, no frills, and sufficient grunt to get out of a bad area.  It also does SSB (and CW, but I’ll leave that to LY2KW).

I could buy a new set, in fact, I may get a FT-857D, as the 897D is a heavy lump of a radio to lug around, and there are times when HF capability is useful.  It is less than ideal on the bike however due to its size and weight.  There was nothing wrong with the FT-290, just its linear was dead, thus I was limited to its barefoot transmit power of 2.5W, even less than most handhelds.

So, I decided I’d try my hand at a semi-homebrew linear amplifier.

The concept

I wanted an amplifier that could achieve at least 25W of transmit power using SSB.  As I’d likely use it for things like WIA broadcasts, I wanted one that would also handle transmitting for a long period of time.

Designing a full blown amplifier on 2m is a bit beyond me with my limited homebrew experience.  It is also an issue sourcing the PCB material needed for VHF projects.  A lot out there call for FR4 grade fibreglass PCBs.  I have no idea what Jaycar sell.  So this was going to be a potential minefield.  Thus, I opted for a kit.

Minikits sell one based on the Mitsubishi RA30H1317M.  The same kit, can also take the 60W module, which sounded good to me.  Most of the time I’d be running it at 30W, but having 60W capability sounded good.  I purchased this, along with the 30W module as well just in case.

I also thought a pre-amp would be nice.  The same supplier sells this preamp kit.  The kit also offers RF sensing, which would allow the amplifier to auto-detect the radio transmitting, and switch into transmit mode automatically.  This also allows for filtering, to prevent reception of pagers (not fun copping an earful of one of those when you’re wearing a helmet-embedded headset riding a bicycle).

Cooling

Minikits recommends using a Pentium 4 heatsink for 30W modules, however it wasn’t clear if this would be sufficient for 60W modules.

I wanted the amplifier module to stay below 100?C while operating with ambient temperatures at 40?C.  Pretty sure I don’t want to operate a radio under such conditions, so it should work fine in all conditions that I’m likely to encounter.

The amplifier module is about 45% efficient, thus about 135W is dissipated when operating at full power.  By my calculations, I was looking for cooling that can provide 0.22?C/W.

A quick search revealed that I could get one via Conrad which in the open air achieves 0.84?C/W.  Combined with a fan, it can achieve 0.24?C/W.  Jaycar sell this fan, which is quite capable.  In fact, two of them will fit across the back of the heatsink, so with dual fans, I should be well and truly within limits.

I placed the order for the heatsink a fortnight ago.  Due to a mix-up, I didn’t get it until Wednesday, but that’s fine, I wasn’t in any hurry.  With the heatsink now in my possession, I today headded to Jaycar to pick up some of the bits and pieces I’d need for this project, starting with the enclosure.

One thing I did neglect to procure today, were the fans… but no biggie, I’ll get those later.

Prior work

Well, technically day one was some time ago.  I had already mostly built the amplifier kit, and the preamp.  The preamp got built way back when I first obtained the kits.

The power amp was built later, however the instructions suggested that I wait until I have the amplifier module mounted on the heatsink before I go soldering it to the PCB.

Amplifier kit and 60W module

Day 1

Having got the heatsink, enclosure and tools, I set to work.  Initially I positioned, drilled and tapped the two M3 holes for mounting the amplifier module.  I haven’t tried putting the amplifier in place yet, but it looks like the holes are positioned pretty well.

Amplifier module on heatsink

My plan, is to bend the pins on the module at 90? and mount the PCB horizontally.  Both module and PCB would be passed through the side wall of the enclosure, with the heatsink outside.  I originally wanted the heatsink inside the case (with vent holes), but of course, Jaycar are not good at providing internal dimensions, and I soon discovered it’d be awkward to fit.

It took a bit of experimentation to cut the hole in the side.  No, I won’t be winning any prizes for my metal work, in fact, it never was one of my best subjects.

Heatsink and empty enclosure

Next steps:

My immediate next step will be to mount the amplifier module, solder it to the PCB, and mount the PCB inside the case.  Then I mount the heatsink and fans to the case.

I have a controller that I have designed at digital logic level, however I’ll need to do some further design work to make sure it’ll do what I intend, before procuring the parts and building it.

For some time now, we’ve been putting up with interference from a few stations, who for now will remain nameless.  Foul language, deliberate interference, the list goes on…

Allegedly some of these people have been doing it for longer than I’ve been alive.

It is as if, these people, believe we are not entitled to use a small patch of radio spectrum to engage in a little friendly chat.

Some have even gone as far as vowing to do “everything they can” to “ruin” amateur radio.

This means war.

Well, we could complain to the ACMA… apparently some have done this already… many times.  If they haven’t acted after 20 years worth of complaints, I don’t think they’ll ever act.  Not without a very substantial amount of evidence.

There is nothing however, that stops us, getting on the band and having a chat, except one thing.  Someone parking on the frequency we choose and interfering with our communications.  Yes, we could QSY, but experience has shown the culprits just chase us up and down the band.

They cannot be on all frequencies however.  One big group, on one frequency, is vulnerable to attack.  Numerous smaller groups, scattered across the band however, is far more resilient.  They cannot be on all frequencies at the same time.  More to the point, more ears open and listening, means more data points … bonus points if those “ears” are directional.

My proposal

What we need to do is stir up some activity on the 80m band.  The 80m amateur band is a wonderful local chit-chat band.  It has almost guaranteed propagation for distances over 1000km on any given evening.  It is open to all license classes.  (Well, if you ignore the DX window.)  I’m proposing a contest with a difference.

Most contests, you make contact with a station, exchange numbers, then it’s ta ta… (or “73″) and you go your separate ways.  Not terribly exciting listening.

I’m proposing a social ragchew contest.  I want to encourage as many people, on as many groups, as possible.  The more people, the better.  Talk about anything you like.  QRP and QRO stations welcome.  Mobile and portable stations, also welcome.  Newcomers, especially welcome.  Make it a large group, or a small group, doesn’t matter.  It doesn’t have to be a formal net, just so long as there’s at least three people.

How will it be scored?

This is something I’m still thinking about… but I’m thinking something along these lines… I would love your input.

For every hour, or part thereof, each member of a group chatting on the same frequency, will get one point for each member of that group.

So if 3 of you talk for 2¼ hours, that’s 3×3=9 points.

Multipliers

• Triple points for every station who has held their license:
  • Less than 12 months
  • Greater than 50 years
• Double points for every:
  • Station that is “mobile” (i.e. moving between localities) or  “portable” (i.e. set up temporarily at some location for less than one week)
  • QRP station (running 5 watts or less)
  • DX contact (overseas)

I’m thinking these should be added together, so if in your group of VK’s you happen to score someone joining your group from Europe (for example) that only just got their license a month ago and is running QRP whilst mobile, add 24 points to each group member for every hour or part thereof that they participate on your group.

What about interference?

More than likely, this will stir up the trolls that seek to ruin our experience.  Part of the aim of this, is that a lot of people will be listening.  The following is something anyone can do, even the shortwave listeners.

• Log the following:
  • the time in UTC
  • your location (latitude/longitude or Maidenhair Locater)
  • the signal strength
  • the nature of interference
• If you can, record the interference
• If you have a directional antenna, point that in the direction where the signal is strongest.  Use that to measure the signal strength, and log the bearing, along with the antenna type.

With enough evidence, we can flush out these serial pests once and for all.

When will it be held?

This is open to discussion… I’m thinking Friday or Saturday night.  I’m thinking it should start some time in the evening when the band opens up, maybe after 7:00PM.

The contest should remain open until the last group participating in the contest goes clear… if a group manages to successfully run to dawn the next day, good on them, maybe there should be bonus points for their efforts.

Let me know what your thoughts are… this is, as I say, a request for comment.  Feel free to get in touch with me directly or leave a comment here.

Dear Mal,

Please.  What is your problem?

This evening, your behaviour on this band was absolutely appauling.  For someone who has apparently had a radio license for longer than I’ve been alive, I am disappointed.  Sadly this is not an isolated incident but for now I’ll turn a deaf ear to previous offences and just focus on tonight’s offence.

I’m not sure if you’re the one that has been playing music over the top of us… some have made this allegation.  I’m happy to give you the benefit of a doubt, but the tirade that followed is very unbecoming of a radio amateur.  Foul language, deliberate interference, not identifying, name-calling, and generally making a nuisance.  As best I can tell, completely unprovoked.

You claimed, “I was here first”.  I was listening on 3584kHz from around 9:15PM.  I did hear Danny ask “Is the frequency in use“.  Several times.  I was mobile at Red Hill at the time.  Prior to this the frequency, as best I could hear with my marginal antenna, was devoid of all activity.  None the less, we gave you the benefit of the doubt, and after listening to your protest, we did the respectful thing and QSY’ed to 3590kHz.

Not a minute after we had done so, there you were, trying to talk over us (and only succeeding with the exceptionally weak stations), and misbehaving as before.  We had left you 3584kHz, moved to 3590kHz, and you followed us up the band.  Why?

All I have heard, is the ramble from a seeming madman.  All I, and others want to do, is use of 2.4 kHz, to have our friendly weekly chit chat.  You are even welcome to join in if you wish to be civil and play by the rules.  If you wish to have a discussion with someone else, we are not going to stop you.

On the 80m band, you’ve got 3.503kHz to 3.700kHz and 3779kHz through to 3800kHz.  You can go anywhere on that spectrum which isn’t already in use, why pick the frequency we’re using?  If you still wish to use the frequency we’re on, why not do the gentlemanly thing, and ask politely?  We’re reasonable, we will move if you ask nicely.

Please, I am asking as nicely as I possibly can, please leave us alone.  We do not wish to interfere with you, please don’t interfere with us.

Regards,

Stuart VK4MSL, and other regulars of the Australia Wide Night-Owl and Insomnia Net.

However, it is worth pointing out, my station only covers the bands between 80m and 70cm (3.5 ~ 450MHz).  The radio can do 160m, however my license doesn’t permit me to go there, and 80m really stretches the friendship of the autotuner as it is.

For true DC-to-daylight though, or very close to it, have a squiz at the portable/field day station setup Roy VK4ZQ has come up with.  This is as close as most will ever get to DC-to-daylight… covering all bands from 80m through to 3cm.  Nicely done.

We had to stop releasing the Qtel client, as it relied on Qt3 which we no longer ship in Gentoo.  On top of this, the ebuild installed non-Gentoo init scripts, fails to build with gcc-4.6 and fails due to underlinking.  (My thanks go to Diego for pointing these flaws out.)

At the moment I’m working on the first problem, which is that the builds that were in-tree are crusty and old.  svxlink did release version 11.05 not long back, and ohh yes, they’ve changed their versioning scheme too to match Ubuntu.  However, their trunk branch is still dependent on Qt3 if you want Qtel.  There is an experimental Qt4 branch, which is what I’ve been working with.

One irritation I had was trying to make it possible to install the client component or the server component.  svxlink has its own, very custom, build system based on recursive makefiles.  (Yes, I know, considered harmful and all that.)  The build system first builds the core libraries, then it starts looking at Qtel and svxlink’s server components.  The first thing was to try and split these up.

The new ebuilds will introduce a svxlink-libs package.  This is relatively straightforward, and it just builds & installs the libasync, libechlib and liblocationinfo libraries.  The catch is when building qtel and svxlink, the build system looks for the built binaries inside the source tree.

I have submitted a patch upstream that remedies this.  Eventually I’ll look at how we can fix some of the other flaws in the build system.  So far I’m still battling svxlink itself, but I soon will have svxlink-libs and qtel packages available for testing in the Portage tree.  svxlink itself will also need to wait until I can set up a test node on simplex somewhere… my O2 looks like a likely possibility.

I’ll keep you all informed as this progresses.  Qtel appears to be working (although I’m battling some funnies with the sound device on the Apple MacBook)… just a matter of fixing some issues with the build system for svxlink and I should be able to have svxlink back in the tree once again.

This is what the offending article looks like:This headset radiates a carrier on the 2m amateur band.  Specifically around 147.000MHz.  In some parts of the world, the 2m amateur band extends from 144.000MHz to 146.000MHz.  Here in Australia however, it goes all the way up to 148MHz, meaning these headsets are effectively pirate stations smack bang in the middle of the FM portion of the 2m band.  They are probably quite legal in the country where they were originally sold, but they are not legal here.

There are a lot of repeaters that operate around 147MHz, particularly in Brisbane.  VK4RBN at Mt. Glorious is one of the most heavily used repeaters in Brisbane, and so you can guarantee there are people listening on that frequency that will hear your transmissions, and will likely complain.  We’re also getting good at direction finding.

So far the importers have gotten little more than a slap over the wrist for the illegal C-tick approval of these devices.  I think the ACMA need to grow some teeth here if we expect to get on top of this problem.  The last offenders were lucky, they got the choice of stopping the use of the headset, or copping a $400 fine … the article was not confiscated.  The importers got a $1500 fine… nowhere near enough, and the devices continue to be sold by distributors.

The end user may not have been technical enough to understand what was going on, but the importers almost certainly should have if they were slapping C-ticks on equipment.

More information:

• VK Logger Discussions: Interference on 147.00xMHz – OMNI WEP-910D
• WIA News: 19 June 2011

stuartl@atomos ~ $ host www.google.com.au
www.google.com.au is an alias for www.google.com.
www.google.com is an alias for www.l.google.com.
www.l.google.com has address 74.125.237.52
www.l.google.com has address 74.125.237.48
www.l.google.com has address 74.125.237.49
www.l.google.com has address 74.125.237.50
www.l.google.com has address 74.125.237.51
www.l.google.com has IPv6 address 2404:6800:4006:802::1011

I knew World IPv6 day was coming up, but it seems it snuck up on me and I barely noticed. Likely a testament to the fact we run a dual-stack network here, and so everything magically Just Worked™ as it should. Indeed, a lot of websites are now dual-stack, as is much of the gentoo.org infrastructure, Google (as seen above), FaceBook, and numerous other sites.

Sadly, a lot of ISPs here in Australia did the demented ostrich act when it came to IPv6. I wonder how many technical support calls they received, with users complaining about websites being slow to load up or failing to connect.

iTel, formerly “Global Info-Links”, now calling themselves “South East Community Telco“… were one of the masses that drove their RFC791-only heads in the sand and pretended that the entire Internet can be compressed into 32-bits of address space. We’ve been waiting to hear back from them on their plans for addressing since January as we’d like to upgrade the 512/128kbps ADSL link we use here. (Anyone noticed this site tends to load up a bit slow? That 128kbps figure is the reason why.)

We’ve been with this ISP since 1996. That’s quite a long innings… We’ve stayed put because until now we’ve been happy with the service. 512kbps was quite fast when we upgraded from 56kbps PSTN dialup (14.4kbps dialup when we first started… still have that modem too!). These days it plods along, but the 128kbps uplink is a notable thorn in my side with my telecommuting. So we’re looking at ADSL2+.

However, there’s one hitch. iTel is only a fairly small ISP. At the moment they do the noble thing of providing static public addresses on IPv4 for all fixed-broadband customers, but how long will that last? The last thing I want, is to sign up a contract for 12 months, then find out that in 6 months they need to move us behind CGN (Carrier grade NAT) to squeeze in some more customers. That won’t fly for us. I’d ideally like to ditch the 6-in-4 tunnel I have with AARNet and go native, or at the very least, swap it with one terminated at the ISP, but that doesn’t seem to be happening anytime soon.

At the moment there is only one ISP I know of that offers any sort of IPv6 connectivity. Internode. Kudos to them for taking the pioneering step! I’m seriously looking in their direction. I’m also hoping the NBN that we keep hearing about, is IPv6 enabled… and I’m holding out with the hope that our little suburb might soon be getting the long strands of glass laid down our street. If it’s only another year or so, it may be worth just hanging on with ADSL1 until then.

Thankfully, we do have the 6-in-4 tunnel through AARNet (and my greatest gratitude to them for providing it). There is a growing community on this newer protocol… I’m also happy to report absolutely 0 spam via IPv6… any spam or malware thus far has been via IPv4 … although I know this won’t last. The good news there is that with one unique address per computer (instead of per customer, or worse, per 100+ customers), it should be easier to track down the guilty party causing such Internet shenanigans. CGN by comparison is likely to be a spammer’s playground.

What am I doing about IPv6 deployment? Aside from my small-time tinkering with the network here… any socket programming I do today is at the very least dual-stack. One of my hobby projects is a digital mode stack for amateur radio… if I get my way it’ll be IPv6-only when used on a computer network.

One of my work projects involves interfacing some proprietary software to some power meters using RS-232 and RS-485 to Ethernet bridging devices. Even though the devices themselves are IPv4 only (and will be for the foreseeable future), I’m designing the software to handle IPv6. Doing this, future proofs the software. Surprisingly, I’m finding it easier to just design for dual-stack than it is to develop a IPv4-only application. If you’re building an application today, dual-stack IMHO must be part of the strategy if the application is going to work beyond this decade.

Some have asked about IPv6 on packet… sadly AX.25 packet does not go anywhere near fast enough to make IPv6 (or indeed, IPv4) networking a viable option on packet radio using existing TNCs… however I think IPv6 will, and should, play a much bigger part in amateur radio communications than it presently does… we can’t expect to hold on to the 44.0.0.0/8 subnet for much longer.

To the ISPs that are lagging behind, I say get moving! IPv4 is older than I am! This is especially true of the smaller ISPs… if you don’t move, you will get squeezed out of the future Internet connection market as address space gets consumed. To the nay-sayers who keep telling us that something else will replace IPv4, to you I say get moving… you haven’t got long to invent this magical silver bullet, in fact I say you’ve left it too late.

This isn’t an isolated case… my mother who works at the Brisbane International airport, often complains about the radio etiquette of her fellow colleagues. A lot of people have a radio thrust into their hands, and haven’t a clue how to use them. In trying to figure it out, they often fall trap to the same bad habits.

I myself have found a lot of this by mistake, and by observing others. A lot of this is also applicable to using regular telephones … I found the tip of standing still when talking helpful when I needed to make a call to emergency services on my mobile phone — the particular spot where I was at the time, the phone would drop out if I moved more than 6 inches in any direction. Learning not to talk too close, or too loudly into a microphone, also helps.

The following is a little chart I came up with. No, the stick figures are not XKCD grade, they’re not meant to be. Click on the image below for a copy as a PDF, or get the SVG source here.  File is provided in the public domain, but attribution would be appreciated.  If you use radios in your workplace, and observe this kind of behaviour in your colleagues, you might like to print this out and stick it on a wall somewhere.