Sunday, February 1, 2015

The Stationmaster


Back in October I wrote about finally getting around to building my multi-port antenna relay matrix.  The matching component to "The Matrix" is my automatic antenna tuner/selector which I've christened "The Stationmaster"

In concept it is a very simple device.  The upper deck is an antenna tuner with motor-driven tuning capacitors and inductance selector.  The lower deck contains a microcontroller which adjusts the tuner components, selects the antenna matrix relays, and sets the channel on my amplifier (which also has motorized tuning presets for each amateur band). Although it all sounds fairly straightforward, the devil is in the details and between the massive amount of wiring under the hood and writing all the software, I'm relieved (and even a bit surprised) that it actually works!  



The entire contraption is built into an old UPS chassis.  I even found a way to utilize the original AC power receptacle opening for some switches!


The tuner uses a differential-T circuit with an extra tunable capacitor instead of a roller inductor.


Just about everything came out of the junk box except for the microcontroller.  No Arduino or Rasberry Pi here, for this project I used a controller from JKMicro called the Flashlite 186.  This board emulates an old 80186 processor and runs a freeware version of MS-DOS.  On top of having loads of digital I/O ports to drive relays with, you can program it in old-school BASIC!  That was just fine with me as this project wasn't about learning new tricks, it was about getting the job done.  I wrote all the firmware using Microsoft QuickBasic in a DOS box under Windows Virtual PC.  I hadn't written anything in QB for years but it all came back to me pretty fast.

There's no school like the old school...

















The board at the top is the microcontroller, the one on the bottom is an analog I/O board with a real-time clock.  The three smaller boards are 16-port relay drivers and the terminal strips are for interfacing to the Matrix and the amplifier. There's almost a 100 feet of 30 gauge wire wrap in there!
On my main station computer I added a bunch of new code into a Windows project in Visual Basic that I wrote a couple of years ago to track propagation indicators and display some nice clocks and the weather.  The VB software was also straightforward although I'm a real hacker when it comes to coding.  I'm sure a professional developer would call my VB code rubbish but, happily, once its all compiled and working no one can tell the difference. Now, when I change bands on the radio (and in some cases when I change frequency within a band), my software will automatically determine which antenna is required, what tuner settings (if any) might be necessary, and what band-channel preset needs to be called up on the amplifier.  It sends all that data to the serial port on the Stationmaster which then goes about switching relays and turning knobs for the desired effect which is a 1:1 SWR on the proper antenna and full output from the amplifier.


The whole shebang.  I had to put in a bigger rack to make room for everything.




Friday, December 5, 2014

The Thrill of the Chase

It was the bottom of the solar cycle when I first started to get a bit more serious about DXing.  If I happened to hear about a major DXpedition somewhere I would likely try to have a listen for it.  Between the low solar flux, my modest home station, and my location under the auroral oval I usually didn't have much luck.  Some parts of the world were simply beyond my reach and propagation often didn't support communications on any band during the brief windows when a rare DX location was active.  I did manage to catch a few operations like K5D (Desecheo) and VP8ORK (Orkney Islands) but there were several once-a-decade type DXpeditions that I will be waiting a long time for a second chance at, like BS7H (Scarborough Reef) and FT5GA (Glorioso).

With the dramatic improvements over the last few years both to propagation and to my station I've come to realize that I have at least a reasonable chance of working just about anything that comes up if timing and conditions are in my favour.  I managed to work all of the major DXpeditions in 2014 (many on the first or second day) and have been successful in picking off numerous smaller operations, inching ever closer to being the first VE8 station to earn "Honor Roll" status by working (practically) all of the current DXCC entities.  Working and confirming 46 ATNOs (All Time New Ones) in the past year has been an amazing experience and, other than a handful of mostly African countries, all the rest I need end with "Island", "Reef", or "Rocks".

This DXCC timeline chart from ClubLog shows the slow march to Honor Roll.  I wasn't very active between 1996 and 2000 and off the air completely between 2001 and 2008.  Now I'm trying to make up for lost time!










I've been lucky with the propagation (from up here under the auroral oval conditions are often very poor) and my antennas aren't anything too special, just a tribander at 70 feet and an assortment of lesser wires and such.  However, my Flex-3000 software radio has an outstanding receiver which is a huge advantage as the signals reaching through the aurora here are mostly very weak and a legal limit (2.25kW PEP in Canada) amplifier sure helps in the other direction.  The real secret, though, to working DX is mostly just paying attention and making it happen.

VP8SGK is perfect example of how it works.  I've never worked South Georgia Island and it is extremely rare on the radio.  The last big DXpedition there was 2002 but every once a while a visiting ham can make a brief appearance from VP8SGK, the British Antarctic Survey base station at King Edward Point.  I had heard that Mike, GM0HCQ, was working on a ship in that area and might be able to get ashore and on the radio during his brief stop there.  I put a reminder in my calendar to check his web page again when he was closer to the island.  A week later I read that his ship was delayed and his arrival was pushed back for several days.  Then the day before he was to arrive he reported that due to the weather their docking was further delayed and he would not be able to operate from the base at all.  It was too bad but that's the way it goes.  At least I had been paying attention! 

The next day at work I just happened to think about GM0HCQ and thought I should check to see if anything had changed.  There had indeed been a change:  he was reporting that if all went well he might be able to get ashore for a couple of hours and be on the radio at 1745z!  I looked at my clock and it was already 1815z.  I checked the spotting network but no spots had been reported yet.  Since it was 11:15am local time, I decided immediately I was taking an early lunch and jumped in the truck for the 15 minute drive home.  On the way I contemplated how strange it was that here was some guy in the Arctic rushing home to attempt to contact some guy who had just arrived on an island in the Antarctic.  That right there is the magic of DXing!  I dashed through the door and into the shack, frantically pushing buttons, turning antennas, and warming up the amplifier.  As soon as the computer was up I checked the spots again and there it was: VP8SGK had just been spotted on 21.200MHz!  Within 20 minutes of receiving the news I was sitting in the shack with the radio on, the big yagi pointing to the South Atlantic, the amp all warmed up, and my ears straining to hear the signal from South Georgia Island.

This story does have a happy ending but probably not what you were expecting.  As it turned out VP8SGK only made 35 contacts and his signal was inaudible here and most everywhere else.  After about 20 minutes of listening to the static and the occasional other stations on frequency calling "in the blind" or just stating the obvious - "I can't hear him..." - I turned everything off, made myself a sandwich, and went back to work.  But I was smiling.  In this case it was all about the thrill of the chase.  Mike says he'll probably be back there again this time next year.  I'd better be paying attention!

DX IS!



Wednesday, November 19, 2014

Sweepstakes from the Arctic

There seems to be a genuine mystique about it that is only partially deserved.  Finding the Northern Territories (NT) section in the ARRL Sweepstakes contest is a requirement to get the Clean Sweep award for working all 83 ARRL/RAC section multipliers.  It certainly is one of the rarer sections, especially on CW, but many years some other section takes the top spot on the 'missed the sweep by one' list.  Still, like anything in limited supply, the good ops know that the longer they go in the contest without an NT station in their log, the less likely their sweep becomes.  But have you ever wondered what its like from this end?  Operating in the Sweepstakes Phone contest from up here is all feast and famine...


Listen to all the terrific contest operators!  Call-Listen-Wait.  A real pleasure to hear after the recent horrific pileups for the FT4TA dxpedition to Tromelin Island...

The Pileups

There's no shortage of people in the contest who want to work NT.  Trying to maximise the number who get into my log is challenging.  As a newly minted VE8 amateur I remember the first time I tried calling CQ in Sweepstakes.  Within a few minutes I was simply overwhelmed by the huge number of callers.  Learning how to efficiently manage the demand took a lot of practise.  There's no good way to work split in a big contest like this so there has to be discipline on BOTH ends.  If the operator has it together then usually the pileup will cooperate nicely. If you keep everything moving at a steady pace you can run at some pretty good rates, too, despite the lengthy exchange!

This rate chart in QSO's/hr clearly shows the 'Saturday Night Doldrums' and this year's 'Sunday Morning Blues'

 
The Antenna Challenge

One of the biggest problems with being an NT station in this contest is that nobody points their antennas at me.  Oh sure, if its getting kind of late on Sunday afternoon some ops will beam our way hoping an NT station will drop by.  That usually does the trick, but for most of the contest guys will beam West if they're in the East and East if they're in the West.  That means its hard for them to hear me off the side of their antenna!  This causes two problems.  First off, its very difficult for NT stations running low-power (or running high-power and having it all absorbed by the aurora!) to make contacts.  The second problem is trying to run.  First I have to find a clear frequency.  Of course 'clear' is a somewhat relative term in a contest but even if I can get a run going there's nothing to stop someone with their antenna pointed away from me plunking themselves down right on top of me and just CQing until I go away (if they even know I'm there in the first place).

The Spots

It doesn't seem right in some way but, like an expedition to a semi-rare DX location, we're almost completely at the mercy of the DX spotting networks.  This is how it works: I find a 'clear' frequency (see above) and start calling CQ.  If I'm lucky, someone tuning by happens to hear me and gives me a call.  Sooner or later, if I don't get run off the frequency (again, see above), eventually one of those callers will spot me on the spotting network.  At that point, all the guys that are watching the spots and want to work NT jump to my frequency and call me resulting in an instant pileup.  The ball is now in my court to work as many of the callers as possible before its ends.  When it does end I start over.  If it ended because someone ran me off the frequency then I have to start over at the very beginning again.  If I'm lucky, though, I keep getting spotted often enough to sustain the run for a while.  Even better, now the guys with their antennas pointed away from me can at least hear the stations calling me (which slightly reduces the probability I'll get run off the frequency) and stations that aren't using the spotting networks hear all the commotion and turn their antennas to find out who everyone is hollering at...

The sky over VE8EV early Sunday morning during Sweepstakes.

The Aurora

I don't whine about the aurora.  Well, not too much anyways.  It is what it is.  From the far North it is almost always there to some degree or another.  Like a variable attenuator in the sky, on some days it only absorbs up to 3dB or so.  Other days it soaks up much, much more.  And that is always on top of whatever else might be attenuating signals at the time, like an elevated x-ray flux or a solar radiation storm.  I was extremely fortunate in 2011 and 2013 that there was very little aurora during SS Phone and I managed to post some great scores.  This year, however, the contest coincided with disturbed geomagnetic conditions.  The aurora was out in full force and the NT and KL7 operators paid dearly for it.  The bands were pretty much dead here for hours on end.  I knew that bands were open 'down South' as I could see the steady stream of spots coming in but up here there was little to be heard.  The few weak and watery sounding stations that were getting through couldn't hear me at all even with the big TH6DXX at 70 feet and both kilowatts.  Sunday morning between 1200z and 1900z, despite my best efforts, I could only get two dozen stations in the log. For you rate junkies, that's about 3.5 per HOUR!  Eventually, though, the aurora let up, I got spotted a couple of times, and away we went.

The Goal

It might sound ambitious but I know that someday I could actually win this thing from up here.  It will take exceptional band conditions (no aurora or anything else bad and decent flux levels), enough aluminum to put a big signal on 40m (in addition to 10-15-20), and not much competition from other NT stations. My rate would have to average 100 per hour for the entire 24 hours which is difficult but not impossible.  I almost had the 'perfect storm' in 2011 but on 40m all I had was a 1/4 wave vertical and I just couldn't get enough rate there to make it happen (although I did do well enough to make the top 20 in the B-class 'big dawgs' category).  My 40m yagi will be going up next fall come hell or high water and I just hope I'm around long enough to get another crack at the brass ring!  In the meantime, I'll keep doing the best I can to make sure no one misses the sweep because they couldn't work the Northern Territories...