Sunday, October 26, 2014

CQ WW SSB - No Contest

I had big plans for CQWW this year.  Conditions were pretty bad in the week leading up to the contest but two things happened that made the difference for me. First off, my annual antenna project did not start out well.  Knowing that it was going to be another year until I can put up a decent tower for my big S-33 yagi, I had intended to put up a smaller, temporary tower with just the driven element off the yagi as a rotatable dipole for 40, 20, and 17m.  A bucket truck was arranged and schemes were devised how to get it into and out of the neighbor's yard through the deep snow.  Thursday was dedicated to getting everything ready.  Rotator serviced and tested.  Mount and thrust bearing fabricated and cables prepped and ready.  Friday after lunch I picked up the truck and went to work.  Everything went smoothly except for one tiny detail: the lift didn't have enough reach to get over the fence to where the tower was going.  It was short by about 6 feet.  With only a few hours to go until the contest started it was clear I wasn't going to have any of my work done.  Then the second blow fell: an X-class solar flare.  That was it for me right there.  No way.  At this high latitude, a solar flare is game over for radio games.

Since I had the bucket truck and was skipping the contest, I pressed on with the next two projects: the 30m full-wave delta loop and the TH3.  Both items were in the plans since the very beginning and last year I had even hung the wire on the Mastrant guy ropes for the delta loop.  It took some doing but I eventually retrieved the coil of wire dangling off the guy and strung it across to the other side to form the bottom of the loop.  Several iterations of tuning with the MFJ-259 later, the delta loop was born.  The feedline is all 75 ohm, thirty feet of RG6 from the antenna, about half of it wound into a choke right at the corner of the loop then down the guy to a 1/2" P500 hardline to the shack.  At the end of the hardline is a short section of RG-11 that trimmed the entire feedline to a 1/4-wave multiple to make a perfect 50 ohm match for the antenna.

When I first checked the loop was resonant on 8.8MHz.  As I trimmed it up to 10MHz I kept getting higher and higher in the air.  I almost ran out of vertical reach on the boom! 

The next trick was putting up the little 3-element yagi on a fixed mount in the middle of the tower pointing at North and South America.  This will be handy for lots of reasons, not least of which will be generating some wave angle diversity when run in parallel with the big TH6 at the top of the tower.  All things considered, the installation of this one went rather smoothly despite having to fabricate a mount and drill mounting holes for it on the mid-point guy station.  Doing this kind of work with a bucket truck sure beats climbing up and down the tower!

From top to bottom: Hygain VB-64DX, the TH6DXX, and the TH3JRK (a TH3JRS with kw-rated traps from a MK4 on the driven element).  You can see the 40m sloper at the top right and the 30m delta loop in the back with the coax choke on the right.

Both antennas work fine and I'm sure the delta loop will rapidly become my star receiving antenna.  It really seems to hear well on all bands, and on 30 meters it works like a charm.  I worked 5R8M in Madagascar on 30m RTTY for a new one tonight!

I also kept an ear on the radio most of the weekend.  There were a few times that NA was fairly loud on 15m and 10m opened up a bit but for the most part I didn't regret my decision not to play.  I even got up in the middle of the night and checked the bands looking for a 10m opening or some low-band action but nada.  The solar flares just kept coming all weekend.  Counting the one right before the contest started there were SEVEN flares including three X-class.  Not much fun for contesting, let me assure you.  Hopefully things will improve markedly before Sweepstakes Phone in late November!

Thursday, October 9, 2014

The Matrix

I have a very good imagination.  I'm also a terrible procrastinator.  When these two things are combined the result can work somewhat to my advantage.  At the beginning of 2012 we decided to move into a house we'd been renovating.  As hams always do, I immediately began planning my new station.  I started with antennas and after examining many possibilites I concluded that it would be possible to put up resonant antennas for almost all the bands and a couple of low-band receiving antennas for good measure.  The next question was how to connect them all.  One of my dreams has always been to have a fully automated station so all the switching would be done based on the radio frequency.  Transmit antenna, receive antenna, amplifier band switching and tuning, even antenna tuner operation, if necessary, would all happen automatically.  If money is no object then something like that is probably not too difficult but if the object is no money then it becomes somewhat more complicated.  I reasoned that I probably had enough junk surplus parts and equipment to build a remote controlled antenna tuner and my amplifier was already a 12-channel programmable unit.  More difficult would be some sort of computer and switching matrix for the antennas.  Also complicating things was my list of requirements.  The system I came up with would have to perform the following feats:

1) Allow switching any antenna to either of two radios.
2) Allow using any antenna as separate receiving antenna or noise sensing source (for the MFJ-1025).
3) Allow using multiple antennas at the same time on the same radio (two yagis pointed in different directions).
4) Allow limited SO2R (single-op two radio) or multi-operator contesting.
5) Had to cost almost nothing.

The last item was a bit tricky but it didn't take too long to figure out the details.  I had a box filled with surplus cube relays pulled from an old PLC unit and I mapped out all the RF paths based on what I could do with a pile of relays, my existing equipment, and the criteria above.

A few tweaks since 2012 but the basic layout has stayed the same.  The antenna tuner always bypasses one radio or the other to the ALTERNATE OUT.  The reject stubs will be a future addition. 

I lined all the relays up on my desk to get an idea of the physical arrangement and that was more or less where it sat for a couple of years.  In my head I would often put it all together and play "what-if" games, frequently going back to the drawings and making slight changes. 

My relay arrangement plan from back in 2012.  Some of my original paper drawings are visible in the upper left corner.

I had been slowly collecting all the parts I needed but when I finally started building the station last fall it ended up being a crash project to get on the air before winter and most of the antennas and the complicated stuff was put off until 2014.  Now that winter is here again its time to get moving on building "The Matrix" because all the other additions depend on it! 

The first step was prepping the relays.  AC and DC ratings are meaningless for switching RF but what I did was eliminate the little wires inside the relays by soldering a solid wire across the two moving poles.  This increased the current and voltage capability along with increasing the isolation.  To further increase the isolation between relays, each was wrapped in aluminum tape and the tape was used to hold all the relays together.  During one of my daydreams about operating this system I started thinking about how much RF current and voltage might be on the line going to the vertical antenna used for transmitting on 80 and 160m.  I don't doubt that sooner or later a relay will end up getting burned and have to be replaced but "much later" is the preferred time frame for that so I added an open-frame, heavy-duty relay for the main vertical feed just to avoid this scenario.

Well, here it is.  The three black cables are RG-59 that I used for the rx lines instead of the originally planned RG-174.  I put connectors on both ends of the bus lines in anticipation of possibly wanting to add future lightning protection or a lumped constant like a big inductor during a 160m contest for example.

An unexpected bonus came in a piece of junk surplus equipment that I found in my collection.  It had multiple N-female jacks all connected with RG-402 semi-rigid 50 ohm coax.  This was a big improvement to my original plan of teflon-insulated open wires and because the antenna jacks did not have to be mounted to the outdoor termination cabinet they also enabled me to make the whole unit as an assembly and install it outside in one piece.  Now that there is snow on the ground that is a huge plus!

Close-up of the taps on the LDF4-50A heliax cable during construction.  Pieces of the copper-jacketed RG-402 came in very handy for this part, too!

The control wires for the relays will all enter the shack directly through a 25-pair telephone cable into a metal box containing back-EMF protection diodes, bypass capacitors, and ferrite beads for each wire.  If there are any particularly stubborn antenna/frequency RFI problems then I can also add RF chokes as necessary.

Close-up of the relay connections.  Each relay has been modified to have one NO contact across the poles and the relays are physically arranged for the shortest possible leads.  I splurged and bought the little push-on connectors to terminate the wires.  Theoretically, if there is a problem the whole unit can be removed from the outdoor cabinet, brought inside and disassembled for repair.

The next step is putting the microcontroller together and writing some control software.  That will be the subject of a post in the not too distant future. When I get around to it ;)

Sunday, October 5, 2014


                    California QSO Party

Call: VE8EV
Operator(s): VE8EV
Station: VE8EV

Class: SOFixed HP
QTH: Inuvik, NT
Operating Time (hrs): 5

Band  CW Qs  Ph Qs
   80:   11      4
   40:    6      2
   20:   27     23
   15:   10      2
Total:   54     31  Mults = 31  Total Score = 6,944



Mostly just a few hours playing with N1MM+, passing out the mult, and getting a few things set up for contest season.

John VE8EV