Better Safe Than Sorry!

I should have known better. I service high voltage equipment all the time at work and the safety precautions are thoughtfully and carefully layered so no one gets hurt. High voltage insulating gloves, voltage sensing wands, locking/grounding disconnects, rubber floor mats, etc. Exacting procedures tie together all the safety apparatus. You do things EXACTLY correctly because you don't want your children to grow up without a father. So why should things be any different with amateur equipment?

My amp has issues. Nothing major, but it's old and sat in an oceanside warehouse for many, many years before I rescued it. Just little things. Like all of a sudden it wouldn't bandswitch properly on any band except 20 meters. Now that I was putting up an all-band vertical antenna I was pretty sure I was going to want to use the amp on other bands. So, while I was putting up antennas and dabbling in the California QSO Party, I decided to take a look at the bandswitch. Oh yeah, and while I'm at it I need to have a look at the meter. The HV metering also seems to have quit...

This is not a decision to be taken lightly. First of all, the amp is mounted in the equipment rack. I can just squeeze in along the side of the rack and reach behind to unplug the amp and disconnect the coax and control cables. The next trick is getting it out of the rack. This ain't no 30 pound Tokyo Hy-Power solid-state wonder. This is a piece of heavy-duty, mid seventies commercial equipment and it weighs 350 pounds! Fortunately, the procedure is fairly well developed. Slide it out of the rack onto a piece of carpet and from there, with a bit of grunting, you can slide it to where you want it. Now that its all disconnected and clear of the rack you can open it up. Two dozen screws to get the top cover (with electrical interlock) off then several more screws and pieces to come off to be able to slide the bandswitch control out a bit to take a look at it.

So I'm happily disconnecting wires and removing screws in the RF compartment when *WHAM* something bites me AND HARD! I'm sitting there rubbing my hand and starting at the amp with the same sort of disbelief as when the loving family pet up and bites you. What the heck? It's not plugged in. The cord won't even reach the outlet unless it's all the way into the rack. The capacitors couldn't STILL be charged. The HV hasn't been on for hours! But obviously, that's exactly what was going on. Fortunately, I only had one hand in the works or I might not be telling this tale.

I pulled out the schematics and started looking at the power supply diagram. Oh, the HV metering is in series with the bleeder resistors. Starting to make sense now. No bleeders, no HV meter, no discharging the capacitors. Oh, and the interlock on the cover only short circuits the primary (low voltage) side of the HV transformer. I sacrificed a few high value 1/4 watt resistors to discharge the capacitor. This thing has an 8 uF oil-filled capacitor which would easily discharge enough current to blow the end off a screwdriver if you shorted it directly to ground when it was fully charged. After I had blown up a few small resistors then I felt I could safely zap it to ground with a screwdriver. Just as a final precaution, I checked it with a meter. The voltage was rising again! There must be another capacitor in the circuit that was back feeding this one and slowly charging it again. It was rising at almost 50 volts per minute. I discharged it again and quickly clipped a ground wire onto the capacitor to hold the voltage down and bleed off the other cap. Once I was sure everything was finally dead I proceded to change out the open bleeder resistor and all was well. The metering worked properly and when you shut the switch off the HV would go from 4000 to zero in 10 seconds.

So, the moral of the story? DO IT RIGHT AND BE SAFE.

EVERY time you open up an amplifier or other piece of HV electronic equipment ALWAYS ASSUME that the high voltage lines are still ENERGIZED until they are SAFELY and SECURELY grounded.

Oh, and the bandswitching problem? I had band program card plugged in upside down!

Ex Luna Scientia

Well, I didn't quite make my deadline of getting it done before summer was over but now it's a done deal. This weekend, in between all the HF antenna work, I did find the time to point the VHF/UHF antenna array at the moon and make a contact. The ARRL EME Contest was running and from this far north the moon was above the horizon for the entire 48 hour period.

Like many things, I have procrastinated for months now on building a computerized antenna positioning unit. The pointing is plenty accurate for satellite work but leaves much to be desired for EME. Fortunately, it cleared up Saturday night and I could adjust the antennas by sighting the moon along the antenna booms. The ferocious winds made it difficult to keep the antennas aimed and the moon actually clips across the sky faster than you might think!

I spent quite a bit of time tuning between 144.000 and 144.100 listening for CW but didn't hear a peep. After a while I fired up the WSJT software and started looking for JT65 signals. It didn't take me long to find KB8RQ. Gary's station in Ohio has two dozen 13 element yagis with 1.5kW on VHF and Saturday night he was RUNNING stations off the moon! Of course not quite the same rate as an HF contest (it takes five minutes to complete a JT65 QSO) but he had a steady stream of callers with few unanswered CQ's. Once I had everything dialed in I could easily hear his tones in the headphones and he was registering -17dB in the software. I had only tried calling a few times when he came back to my pair of 13 element yagis and 100 watts.

I spent another hour or so after that tuning around but never heard anyone else calling CQ. I copied a few stations calling other (unheard) stations and lots of distinctive '73' tone pairs but didn't make another QSO. Hopefully this is the motivation I need to get the 2m linear amplifier built and finish the computer antenna controller!

MFJ-1025 Noise Cancelling Signal Enhancer

If you're anything like me you're sometimes troubled by noise. At my home QTH I only get two kinds of noise: man-made and natural. S9 noise on all the low bands and sometimes troubling on the upper bands too. I finally decided to try one of the MFJ-1025 "Noise Cancelling Signal Enhancer" box. All the online reviews seemed to generally agree that this was one piece of MFJ gear that did what it was supposed to.

The theory behind it is actually quite simple. Take the signals from two different antennas and adjust the phasing to null or enhance signals from different directions. One thing that needs to be emphasized is that the more closely matched the antennas are the better it will work. I used a 23 foot vertical as the main antenna and an 18 foot vertical whip about 30 feet away as the noise sensing antenna.

Does it work? Well, it doesn't work miracles but it does sometimes work wonders. As long as the noise that is troubling you is from a single direction it WILL be able to reduce it. How much depends on many factors, mostly how well you are receiving the noise on each antenna. One thing I did do right away was to replace the little light bulb used as an RF 'fuse' on the noise antenna input with a relay to ground the input when I transmit. The light bulb would probably be okay if I was only running 100W but a kilowatt into the main vertical popped the little bulb in short order.

It definately takes a bit of practice to get used to operating it but the procedure is pretty straight forward. Adjust the gain controls for each antenna so the noise is at the same level on each antenna and the carefully adjust the phase control for a dip in the noise level. A little tweaking of one level control, adjust the phase control for minimum noise level and you're done. It really helps if you set your radio AGC control to 'fast' during the adjustments.

This little gizmo is aleady on my indispensible list. For more info, Tom W8JI has a nice description of the theory on his web page at http://www.w8ji.com/mfj-1025_1026.htm

Winter Wonderland

The snow is on the ground and the temperatures are below freezing. That traditionally means it’s time to start doing antenna work. I don’t really know why we (actually me) can’t get our (my) act together and do it during the summer. There’s always so much going on when the weather is nice and a never ending litany of excuses. It’s too hot, it’s too cold, it’s raining, there’s too many bugs, there’s better things to do, etc, etc. Once October hits, though, the situation seems to reverse itself. Yeah, it’s 5 below zero outside -BUT- it’s only gonna get COLDER. And DARKER. And WINDIER. And CQ World Wide is only a few weeks away now… Better suck it up and get onto the antenna work before it’s REALLY miserable out there.

So I spent last weekend up on my roof putting up a 23 foot vertical antenna for the low bands and an 18 foot vertical antenna for the noise sensing antenna to use with my MFJ-1025. Before I got started, I modelled several different rooftop antenna and radial configurations in EZNEC. It’s quite amazing what little things make a big difference and what things make very little difference. The end result of the modelling was to put the vertical on a tripod mount at one end of the roof with two 18 foot radial wires down to the eaves and one 33 foot radial wire along the ridge of the roof. This gave a reasonable performance and efficiency on all bands. I modelled it with a few more and different length radials but it didn’t seem to make much difference. I fed the antenna with a chunk of LDF2-50 hardline I had handy and it loads up quite easily with the internal tuner on 40-10 meters. I can load it for 80 and 160 meters with the external tuner but I really don’t expect too much on those bands. Judging by the contacts I’ve made so far the modelling seems to be valid. I haven’t had a chance to play with it too much yet but I have made a few contacts on several different bands and on 17 meters I even got a 10-over-S9 report from a JA station and worked the TX5SPA expedition in the Austral Islands.

The weekend after the vertical went up it was time to start on the big project. Originally scheduled for late June, Wally and I had planned to permanently mount the TH6DXX yagi up at the contest site. The setting for that is a 40-foot guyed tower on top of a 60-foot high water tank. We had hung temporary wires from the water tank last winter during contests but hadn’t exactly figured out how we were going to get the big yagi up to the top of the tower. I’ve done enough tower work to know there was no way I was going to climb it. I don’t like climbing towers to begin with and old, rickety, light duty guyed towers are a non-starter with me. However, one day last spring when we were taking down the wire beam after the ARRL DX contest, I noticed that there was a hinge on the bottom edge of the steel pocket that the base of the tower sat in. Looking more closely, I realized that if the bolts were removed from the bottom plate it would swing open and allow the tower to drop through along the side of the water tank.

So this weekend we went up and bolted a small winch to the edge of the base frame and eventually got the tower lowered down, the old un-used VHF antennas off, and the top section removed. We might have actually pressed ahead and installed the yagi but even though it was only a couple of degrees below zero the wind was howling all weekend. Once all the demolition was completed we decided to call it a wrap for the weekend and enjoy the Canadian Thanksgiving holiday.

Today I got the rotator mounted in the top section and we should be all ready to put the yagi up on Saturday. Wally, VE8DW, has been taking pictures so I'll post the results of our efforts next weekend when we're done.

VC8B Write-up

I had my doubts about how successful this operation was going to be. I was concerned about the cost of getting all the equipment up to the island and back but mostly it was propagation that had me worried. At 72 degrees North the community of Sachs Harbour on Banks Island is well into the geomagnetic polar cap area and I had no idea what kind of conditions to expect. The forecast was for unsettled conditions (the aurora is always unsettled to some degree or another at that latitude) and coming off of the geomagnetic storm a few days earlier I had visions of calling CQ all weekend with no takers.

As it turned out, I was able to get all my freight onto a cargo plane hauling groceries up to the tiny settlement so I only had to pay shipping on my return flight back to Inuvik. With 200 pounds of radio equipment (not including my work tools) that cut $600 off the total cost of the expedition. I probably could have gotten the gear home for free as well but that would have likely meant leaving it behind and I was not about to do that. I had a warm fuzzy feeling watching my equipment being carefully loaded onto an airplane and then two hours later watching it get gently unloaded straight into the back of my truck.

So far I'm the luckiest guy in the world when it comes to expedition propagation. On my April trip to Ellice Island as VX8X I was blessed with 48 hours of extremely quiet geomagnetic conditions that exactly coincided with the timing of my operation. This time as well I had just missed the biggest geomagnetic storm in months and the aurora afterwards was relatively calm for all four days on Banks Island. To top it off there was a even a weak sunspot group to help things along.

My biggest problems turned out to be totally unanticipated. The first glitch was mosquitos. Banks Island is a very windy place and mosquitos are not usually much of a problem but on the Thursday afternoon when I arrived they were swarming en-masse. Now don't forget, I live in the Arctic so I know all about mosquitos but these ones were something else! Of course I didn't bring any bug dope and the only store in Sachs Harbour was closed Thursday afternoon. Fortunately, I managed to scrounge up a bottle of Off! For Kids. Not exactly the heavy duty, 30% DEET stuff that I'm used to but it did get me through the assembly and raising of the antenna without too many bites. I set up right at the airport in Sachs Harbour and had the convenience of a 30-foot high tilt-over lighting pole to mount the antenna and rotator. A pair of ratchet straps were used to secure the 10 foot long piece of pipe I had scrounged on my last visit to Sachs and surprisingly it didn't slip or twist all weekend, even with winds that gusted to 60 knots.

Once again the little TH3JRS baby yagi did the job almost as well as a full-size tribander but at half the cost and a third the weight. The little blue equipment shack was my home for four days.

Aside from the mosquitos (which disappeared after the antenna was up and weren't seen again until it was time to take the antenna down on Monday morning) my biggest pain in the butt (literally!) was my operating position. I had originally planned to take a folding canvas lawn chair with me but it got cut at the last minute to save weight. That left whatever I could scare up on site which turned out to be a cushion and some foam rubber on top of a big cable reel. At first it seemed more than adequate but after a few hours I was quite sore and no amount of adjusting the number of pieces of foam or layering with cardboard helped the situation. I ended up only being able to operate for four hour stretches with a four hour rest in between. With a comfortable chair I probably could have spent 50% more time on the air. Fortunately, I did manage to borrow a rather comfortable folding cot to put my sleeping bag on so I didn't have to sleep on the cold steel floor!

As I mentioned, band conditions were not too bad at all. There were a few periods where not much was heard but more often the band (I only operated 20 meters) was open to anywhere I chose to point the antenna at. On top of that there was tremendous gray line propagation 'overnight' (the sun never quite set there) with very strong signals into Europe around 0600z and then Asia a few hours after that. Once again I confirmed that a small yagi and an amplifier is an unbeatable combination for this kind of operation. I got many, many reports of 20db-over-S9 and was able to turn the antenna to whichever part of the world would generate the best rates (or to whichever part of the world suited me at the time).

As usual, I tried to make sure to cover all areas of the world as equally as possible. Looking back at the log I actually spent more time on Europe and Asia than I did on North America but ended up with 50% of the stations worked being W/VE. Every evening I was able to work 200-300 stations during North American sunset. The rest of the time I spent alternating between Europe and Asia. Propagation to both areas was good but the Asian stations just didn't seem to be around in large numbers and the European stations were just plain hard to work. Three times over the course of the operation I had to give up on Europe and turn the beam elsewhere. Call, then listen. It sounds so simple. Everyone else in the world doesn't seem to have a problem with that so why is it such an issue with some European stations?

One of those times was around 0600z Saturday night during the IOTA contest. I had sacked out for a few hours in the evening so I could get up for Eu sunrise and then work Asia until morning. I pointed the antenna over the pole and tuned through the band working the few stations that were calling CQ. After receiving several comments about how loud I was I easily found a clear spot and started calling CQ myself. I worked several stations in short succession when 'the packet spot heard round the world' went out. Now I'm not sure exactly what happened but I imagine that 95% of the European stations were happily working away on the lower bands when they saw the 20m spot for VC8B come up. At that moment they ALL clicked on the spot, flipped over to 20m and started calling. And calling. And calling. I was reminded of the old Bugs Bunny cartoon where all the animals are fleeing from the Tazmanian Devil and Bugs is trying to find out what's going on but no one will stop to talk to him. I tried to call a couple of stations back but it was just no use. I laughed out loud and just sat back and listened. After two full minutes of non-stop, 20-over-S9 mayhem I finally shook my head and turned the beam to Asia (which from here is 90 degrees to Europe), found a new frequency and just stayed there for the rest of the contest.

Now, in all fairness to the Europeans I also have to mention what happened Sunday evening. The NA sunset peak was winding down and I had just finished putting the last few hundred North American stations in the log when someone mentioned there was a Russian station trying to get my attention from off the side of the beam. I turned the beam and started running Europeans. Now usually I'll run Eu for about 5 minutes before I have to go split frequency and another 5 minutes before I have to start going by the numbers. This time however was totally different. All the stations were perfectly behaved and no one was calling out of turn. I didn't have to go split, I didn't have to go by numbers, it was just smooth sailing. In an hour I put over a hundred Europeans in the log, by far my best run rate to Europe ever. What was so different this time? Beats me. Maybe the professional ops get up early and the lids like to sleep in. Either way, it was a very pleasant way to wrap up the operation.

I shut down after that and went to bed as I still had some work to complete Monday morning in addition to tearing everything down and packing up. Final QSO tally was somewhere over 2000. Logs should be online tomorrow and I hope to have the cards ready to start sending out by the second week of August.

73 and thanks for all the contacts,

John - VE8EV

IOTA VC8B SO24SSB HP

Call: VC8B
Operator(s): VE8EV
Station:
Class: SO24SSB HP (DXpedition)
QTH: Banks Island, NT

Operating Time (hrs): 15

Summary:

Band CW Qs CW Mults Ph Qs Ph Mults
----------------------------------------
80: 0 0 0
40: 0 0
20: 0 0 683 53
15: 0 0
10: 0 0
----------------------------------------
Total: 0 0 683 53 Total Score = 222,441

Club:

Comments:
Fairly decent propagation on 20m but of course no
other bands available due to the extremely high
latitude and 24hr daylight.

Full write-up at http://ve8ev.blogspot.com

73
John - VE8EV