Tuesday, February 16, 2016

Trying New Things

One of the old saws regarding amateur radio is that should you become bored with it there is always something new to learn or do to rekindle your interest. This is often very true. However this advice is frequently ignored by many. It's easy to do as we grow older and we get a little too comfortable or set in our ways.

When I returned to the hobby in early 2013 I immediately tried something new. That was QRP, something I've never done before. Oddly enough the challenge of making contacts with only a few watts and a minimalist antenna only spurred me onward. It eventually led to over 200 DXCC countries with 10 watts or less and some excellent placing in international contests. Another effect was to renew my interest in high-performance antennas and improve my operating skills.

With that in mind I have been trying a few new things recently, and I have plans for more. I'll briefly relate these today. My hope is not that you'll want to do the same, but that you'll be spurred to try one new thing, of your choice, in the next month. It can be as simple as turning on your radio and pressing a button you've never before pressed.

12 meters

I've never cared for 12 meters. I don't know why. It's not because it's a WARC (1979) band since I am very active on 30 and 17 meters. I am also very active on the adjacent bands, 10 and 15 meters. It isn't even because I have no antenna for 12, since that has never stopped me on any other band, including 160 meters. My attitude is completely irrational. I suspect the same is true of many of our likes and dislikes, be it in amateur radio or in other matters.

My rig has an internal tuner so one day in January I forced myself to make a QSO on 12. I loaded up the Explorer 14 with the tuner, turned it broadside to Europe (it's really just a non-resonant dipole on this band) and called the first station I heard. A minute later I had my first 12 meter country in the log: DL. That seemed appropriate since a DL was my very first QSO when I got on the air in 1972.

I did nothing more on 12 meters until February. Then, on a bit of a lark, I called VP8SGI on South Georgia. One call and the DXCC #9 wanted country was in my log for country number two. Signals were weak, my tuner losses were high, but there seemed to be no other callers. Sometimes that's all it takes.

I have since gone on to make a few more contacts on 12 meters. I still don't love it. I have more countries on 160 and 6 meters than on 12. Maybe that'll change. The important thing is that I did it.

Assisted contesting

At the time I went QRT in 1992 there was no such thing as assisted contesting. Well, except for a few "mavericks" who seriously bent the rules. With global DX clusters and RBN, and supportive contest software, it is today very easy to operated in the new assisted categories. But old habits die hard. I am of the generation that grew up believing the single-op contesting maxim: a boy (or girl) and a radio, and nothing else.

I have nothing against assistance. Indeed, I use the spotting networks daily for DXing and I don't feel diminished for doing so. In the past I was primarily a multi-op contester, and I was not disturbed by the assistance of my team-mates, whether for logging, copying weak signals or gathering multipliers. Like many I continue to associate non-assisted operation as the measure of operating ability and station-building prowess. That is a prejudice, not a valid conclusion. Assisted operation involves unique skills and has a place in radio contesting.

The multi-op I joined for CQ160 CW was assisted. It was a bit like being thrown into the deep end of the pool when you can't swim: you learn or drown. That's an exaggeration since our operation was a very laid back affair. Every operator made use of the RBN feed as conditions, ability and interest dictated. In theory, nothing on the band is missed and call sign typos are avoided by the use of machine code readers at the skimmer sites. Most often I've been on the other side of the equation whereby assisted operators are drawn to my feeble QRP contest signal.

Our spot feeds were restricted to skimmers in the same broad geographical area: eastern Canada and the northeast US. That way we avoided spots for stations not workable from here -- we did not have the equipment needed to run our own skimmer. N1MM software helpfully plots the spots on a band map, colouring them according to whether or not they are needed multipliers. Stations already logged were not shown.

When I first sat down to operate for a one hour shift the spots were little more than a distraction. It was early in the contest and we were focussed on running. This is the time of the contest feeding frenzy. Leave your run frequency for more than 10 seconds to pursue a spotted station and you'll lose the run frequency. At that point in the contest that loss more than offsets the gain of pursuing a spot. You learn that very quickly.

Later, and especially the second night, the situation is very different. You can switch to S & P (search and pounce) and maintain a high rate purely by pursuing spots. You see the blue coloured call sign in the band map, click on it and wait a few seconds for the right time to call. It's very fast: point, click, enter. That's the easy part.

When you are running you can still pursue spots, once the rate for everyone drops enough that you can hold a run frequency more easily. This is where the skill comes in. It took a bit of practice to become efficient and effective at simultaneously running and pursuing spots. The process is simple enough:
  1. Call CQ.
  2. Answer? Work them. No answer? Click on a spot.
  3. Call the spotted station. Answer? Work them. No answer? Click on the CQ Frequency.
  4. Back to step 1.
I soon learned to keep a mental note of which unworked spots I most wanted or I felt were most workable. Step 2 was thus executed very fast. You don't want to waste time perusing the spots anew each time. Not once did I lose the run frequency. However there were a few times when I did need to assert myself in marginal cases.

The process grew easier at the contest progressed. Few spots showed up since we'd already worked everyone available. More time could be spent chasing multipliers and "fresh meat". The latter are contesters  or casual operators who show up only briefly to play around for a short time. They are very popular, drawing instant pile ups of assisted stations. That was also the time that busted calls were prominent in the spots. This happens because busted (poorly copied) call signs are not in the log. It pays to rely on your ears, not the spots, before calling or logging these stations.

I enjoyed the experience of operating assisted. At some point I expect to try it again. Although not entirely to my taste it is a new skill worth honing, if only as preparation for future multi-op opportunities. It's a little like a video game or (if you're my age) pinball. If nothing else it keeps you productively occupied while the machine sends one CQ after another. It is less stressful than SO2R (single-op two-radio), but with transferable skills.


Yagis need to be rotated, and rotation means bearings. Bearings allow rotation of machinery while supporting loads. Depending on the application in an antenna system the bearings may need to support radial loads, usually due to wind, and axial loads, due to weight of mast and antennas. Often they need to do both.

Most ham rotators are integrated with bearings that will support a quarter-tonne or more of axial load and somewhat less radial load. These bearings are supplemented by mast bearings that help to protect the rotator from radial and loads and bending stress thus permitting tall rotating masts supporting large yagis and their wind loads.

Unfortunately ham market bearings are not always the best. For the typical small tri-bander they may be adequate, and it may be acceptable to service or replace them every 10 or 20 years. For the larger arrays I am planning industrial bearings are needed for the rigours of high loads and extreme environments. The prop pitch motors I acquired last year include a chain drive, bearings and plates for the LR20 tower I hope to put up later in 2016.

Two identical 90 mm bearings support the top and bottom of the chain-driven 3.5" O.D. drive shaft. The antenna mast fits inside the top, secured with bolts. The bottom bearing mostly acts as a thrust bearing, with a collar to apply axial load to the lip of the inner bearing surface. The top one is for lateral wind load, which requires no collar. I plan a third bearing for lateral load on a third plate on the 3" mast (to be acquired). However I had little knowledge of industrial bearings going into this. It was time to learn.

Screen capture taken from the NSK rolling bearing catalogue; the specs tell the story
The bearings I have are NSK 6218 DU. An internet search quickly uncovered this bearing's specifications. NSK is a the manufacturer, 6218 is the model and DU is the type. The 6218 is a 90 mm bore deep-groove ball bearing with a rubber seal to protect against dust and water ingress. With a suitable oil or grease (grease is what is typically supplied) this bearing works over the wide temperature range we experience in this climate. They do not appear to have had external weather hoods in their previous use, and they had been outdoors for many years, both in service and storage. Both were seized. The previous owner and another prominent big-station owner encouraged me to try and save them. Replacement cost is in the range of $175 to $200 apiece.

My first act therefore was to learn about rescuing seized, sealed industrial bearings. I have some experience servicing small bearings, including sealed bearings. Combining that experience with the advice I received I proceeded to submerge the bearings in a bath comprised of equal parts solvent and light oil for a few weeks. I suspected caked debris and grease/oil were fouling the bearing rather than deterioration due to rust, pitting or flaking. After bathing them I faced a problem. There is no easy way to grip the housing and apply torque to the inner surface.
Deep-groove sealed bearing custom fitted to a LR20 tower plate

Looking around my workshop I found an answer: a short length of 2x4 lumber can be hammered into the ~3.5" opening. Each bearing was remounted on a tower plate, to hold it, and a wrench was applied to the lumber. Some motion resulted, but not enough. So back in the bath they went. A week later I was able to force them both into full rotation. I then built a simple jig by which I could turn the bearings at moderate speed with a drill. The result was two functional bearings. I now know something about servicing industrial sealed ball bearings.

With the NSK rolling bearing catalogue in hand, a guide to their application and a list of local bearing suppliers I am now in good stead to fulfill my future bearing needs. This includes side mounted yagis as I discussed in a previous article. I will also explore weather covers for the bearings rather than solely relying on their rubber seals. Since there are no adjusting screws it is necessary order the exact or next larger bore size. A shim, if required, can be made from sheet metal.

Now my only question is: how did they get the balls into the bearing?

New new things

I will have many learning opportunities when I build my next station, which will include larger and more towers and antennas that I've every had before. I have worked on the large stations of others but not for myself. So I know some things but not everything I will need to know. A few examples:
  • Reinforced concrete forms and structures
  • Yagi fabrication
  • Tall, rotating (and climable) masts
  • Phased vertical arrays
Inside the shack I have other needs to support SO2R and multi-op contesting. That, too, involves many new things to learn.
  • Antenna switching matrices
  • Station automation (software control and integration)
  • High-power band pass and reject filters
That's my immediate list. More will be added later. Are you learning new things? Are you planning to do so? If not it may be time to push yourself out of your comfort zone and try something new. I know from private correspondence with readers of this blog that many others get a thrill from learning and trying new things. We can all learn, and help each other along the way.

Amateur radio has a lot to offer. As I approach retirement I get fewer learning opportunities from business and other fields that have kept me occupied for decades. This hobby more than makes up for that learning deficit.

No comments:

Post a Comment

All comments are moderated, and should appear within one day of submission.