Friday, December 14, 2018

Rebuilding a Ham Rotor


A bit of patience and some time... 

Following up on my article on rebuilding/refinishing a tower (https://t.co/WY4VtD82kT) I promised to also write an article on rebuilding an antenna rotator. The rotator described here is a typical model marketed for many years by Hy-Gain. The information also applies to many CDE and MFJ rotators. 

For many years I used a light duty TV rotator to turn a 5 element VHF Yagi. With my greater commitment to HF and contesting came the desire to improve on my wire antenna and graduate to a beam. Doing so required a beefier support structure and, because of the Yagi antenna’s directional nature, a means to rotate it in the direction that I wanted to work.



For anyone contemplating a similar upgrade, I should add that I do not find that I can get significantly more stations than I did with my Carolina Windom off-centre fed wire antenna but, the weak-signal noise that comes with distant stations is much less now and therefore they are easier to copy. Both antennas happily coexist on my tower and I find one or the other most useful depending on the band and my purpose.

I was fortunate to receive the donation of a Ham II rotator and control box, although it was in pretty rough shape after many years atop a tower. Birds had coloured it multiple shades of white and it was caked on pretty heavily.  My first task therefore was to scrape and wash off as much of the debris as I could. Once that was done I decided my next move should be to hook it up to the controller to determine if it was usable - it wasn’t.

The 8-terminal connection plate was so badly rusted that 6 of the screws could not be loosened with any amount of penetrating oil, rust remover, heat or any other means at my disposal. The previous owner had clipped the control cable so there were a few centimetres of wire available that I could connect clip-leads to. Using this method I was able to connect it to the controller and I switched on the power… nothing! I tried the rotation control in both directions with no luck. The illumination bulb on the controller lit but that was it.

Twisting the top of the rotator produced some motion however it soon became clear from the rust debris that fell from between the two rotator sections that internal work was going to be required. I did manage to find some documentation on the Internet that provided some insight on how these rotators are assembled along with warnings that, if you do take them apart, you had better mark your steps so that it goes back together the same way. The Ham series of rotators goes back a long way and have progressed through several models and versions. I also found out that it is not always clear which version you may have as labels have long since disappeared in the elements of the outdoors.
I decided that I had nothing to lose so I mounted the rotator on a section of pipe on my shop vise and examined the 4 bolts holding the halves of the external shell together. Needless to say they were also rusted badly. The shell itself is pot metal so very fragile, something to keep in mind when starting this task. Over the next several days I soaked the bolts with every chemical I could think of. I was eventually able to loosen and remove 3 of the 4 bolts. I drilled out the last bolt, eventually re-threading the hole to accept a replacement. It was finally apart!

As I mentioned, there are plenty of warnings about separating the shell. I dutifully made a mating mark on the halves and started to lift the bottom (it is mounted upside down for service). Despite my care, several ball bearings rolled onto the floor of my workshop and under those places that made retrieval difficult. Note to anyone attempting this process… place a shallow cardboard tray under the rotator. I was expecting rust but I wasn’t quite prepared for the revelation that a number of the ball bearings were no longer recognizable as such. At this point I contemplated putting the unit in the recycling bin.

Not one to be deterred by a challenge I decided to have a go at clean-up. Over the next few days I carefully cleaned out as much rust as I could. I removed the rusted terminal plate and soldered on a pigtail that would later accept a waterproof connector. New terminal plates were available by mail order (about US $25 with shipping) but I figured a new one would rust again just as quickly and as I was well into the innards a better means was available.

The motor mechanism was easily disassembled but I took special care to take lots of photos as I went along and I was happy I did so afterwards as it made re-assembly that much easier. The gears were not rusted but did have grease and other debris on them. A solvent bath cleaned things up nicely. The manufacturer recommends that very little grease be used internally as it only gathers more dirt.



I paid special attention to the rheostat on top of the motor. This is the most vulnerable part of the rotator, and the most expensive to replace. it consists of a circular core wound with nichrome wire. As the rotator turns a brass wiper travels across this winding thereby varying the resistance. This resistance is shown on the meter movement that shows the bearing of the antenna N-E-W-S. The wire is very fine. Two things are most common when things go wrong. The rotator is forced past its limit of travel at either end, bending the brass wiper. This can be caused on early models without a mechanical brake and even on later models as the brake fails to activate in time due to rotational forces of the antenna. Third party add-on kits can prevent this from happening [link]. The second common cause of failure is a break in the nichrome winding of the rheostat either by a mechanical mishap or burn-out through improper connection to the control box. The winding of my rotator showed a burn mark confirming the latter. Fortunately it was at the extreme end of rotation and I was able to make a repair. The wiper had a minuscule void worn through where it had travelled over the wire. This was repaired with a small drop of solder on the outside surface. Resistance readings confirmed that it operated smoothly over its travel from end to end. I was pleased with myself for not having to spend the money (and waiting time) to order this as a replacement part.

I found replacement ball bearings were readily and cheaply available in bulk on eBay. I needed 100 but ordered 250 as the price was almost the same. I paid US $15 for the lot. Contrast this to a local supplier who wanted 25 cents per ball bearing. Again the caution from the manufacturer not to use too much grease. A thimbleful of white lithium grease is all that is required for all gearing and the 100 ball bearings to operate smoothly.

Now came the time to put it all together again. Fortunately this was not as difficult as I imagined while doing the disassembling. As long as you put the ring gear in the right way around, read ‘ooops’ here…, then move the rotator (wiper) fully counterclockwise, and manage to slip the motor assembly into the toothed ring gear with an angled downward movement, all the while mindful of the markings you made earlier, all should go well.
I used stainless steel hardware to reassemble the shell halves. I have read nothing to indicate that this is improper and I figure it will be much easier should I ever have to open it again for servicing.





I acquired a waterproof 8-lead connector pair that will make it much easier to disconnect and service the unit in future should it have to come off the tower.
This is a do-able project for most of us with basic skills if you go step-by-step, take lots of photos and mark your work pieces as you disassemble.
In this article I refrained from listing each assembly/disassembly step, as the factory manual is readily available on-line at http://bama.edebris.com/download/cde/ham-ii/ham2.pdf

I used it as my guide and was able to figure it out without too much difficulty. This guide also provides nominal resistance readings so you can troubleshoot the rotator before taking it off the tower. Should you need to order parts, the most quoted supplier is Norm’s Rotor Service http://www.rotorservice.com/

~ John VE7TI





Sunday, December 9, 2018

Yet Another Knot...



The Buntline Hitch


Knots are used frequently in our hobby. From securing loads to securing antennas, a knowledge of some basic knots is very valuable. We are considering a General Meeting session later in the season to see some knots and their application demonstrated. In the meantime, we’ll feature some common knots for you to practice. This month the Buntline Hitch.




Use this knot to fasten items such as snaps and rings to rope or cord. It forms a small, net and very reliable knot. Not to be used however for tying a climbing rope.






Wednesday, December 5, 2018

A Look At Foot Switches



There's A Variety Out There... 

Foot switches were never a must-have Amateur Radio accessory… that is until I started contesting about 12 years ago. I used a desk mic and the built-in Push-To-Talk (PTT) switch on the mic base. It was fine for general chats. I switched to a headset sometime around 2000 and it did not have a built-in switch so I started examining alternatives.
My first trial was with a push-button hand switch.



It was useful but cumbersome and very un-ergonomic as I always had to have at least one hand on the button. Not a good choice for contesting, even with the paper logging I was using at the time.

Then I recalled my time in the Vancouver Police Department 9-1-1 call centre. Radio Operators there use a foot switch exclusively, leaving both hands open for other tasks.  My first foot switch was a home-made affair. It worked just fine but did not have the right weight or ‘feel’ and moved around on the floor. I  then modified  a foot pedal from my woodworking tools by removing the AC  socket and replacing it with a standard ¼-inch phone plug, the norm for PTT input.


It was much better, had a decent weight and a solid PTT contact as long as my foot hit the correct part of the pedal, something that doesn't always happen in the frenzy of a good contest pile-up or an attempt to get that rare DX.





It wasn’t until about 2008 that I noticed that the sustain pedal on my wife’s Roland piano used a ¼-inch phone plug as well. Although I don’t play myself, I found out that these are quite heavy and  was told that it did not normally move around.


I used that pedal for a while but, to avoid the inevitable: “Did you take my pedal again?” I decided to shop for my own. A trip to a couple of local musical instrument stores produced several good candidates. I tried some out… to questioning stares as I didn’t play a piano while doing so, but instead listened for a smooth and solid click and tossed it in the air a bit to judge the weight. I took one home for $25 with an assurance that I could return it if dissatisfied with the product. It turned out to be a Chinese-made item but it worked like a charm with all the right attributes and is still in use today.

As it turned out it also has a normal open (NO) and normally closed (NC) selector switch. Apparently this is because some pianos require that option. For Amateur Radio use the switch should be set to normally open (NO) to trigger the PTT when the pedal is depressed otherwise the radio would transmit constantly except when the switch is depressed.
Amazon has pedals starting around $20 and eBay has them starting at about $15. My recommendation is to visit your local music store and to try a few so you can determine if they tend to slide on the floor, if they have a nice solid click and if they are normally open.

~ John VE7TI




Friday, November 30, 2018

The December 2018 Communicator


Here is the latest Communicator 

Amateur Radio News from the South West corner of Canada and elsewhere. You will find Amateur Radio related articles, profiles, news, tips and how-to's. You can download it as a .PDF file directly from https://goo.gl/n3WNwe




As always, thank you to our contributors, and your feedback is always welcome.  My deadline for the next edition is January 24th. If you have news or events from your Vancouver area club or photos, stories, projects or other items of interest from elsewhere, please email them to the communicator@ve7sar.net

Keep visiting this site for regular updates and news.

~ 73,

  John VE7TI


  Communicator Editor

Wednesday, November 28, 2018

Can Hams with a Canadian Basic Licence Program and Use Land Service Transceivers?



A Question was raised about the required licencing level to program and use transceivers manufactured for non-Ham (commercial) use. These are also known as land service radios. The opinion put forward is that there should be no issue with a Basic with Honours (or even a Basic only) qualified amateur from self programming and using such land service radios on the VHF or UHF amateur bands.

As far as the rules are concerned, we are simply dealing with what is said in Innovation, Science and Economic Development CanadaRadio Information Circular RIC-3, section 4.4 "Privileges and Restrictions". And there in Subsection 4.4.1 it says, regarding the "Basic Qualification": 

Can operate all station equipment, except for "home-made"  transmitters. 

Footnote 1 says:
"Build" in the context of the Basic Certificate is limited to the assembly of commercially available transmitter kits of professional design.

Obviously, the prohibition stated above for the Basic amateur not being allowed to build transmitting equipment does not apply to the context of programming radios for operating on specific frequencies (or modes) especially if such programming is part of the inherent design of the product.

For example, the readily available Tait commercial radios are designed for the land mobile service and must comply RSS 119 to be marketed in Canada for that service. This is a much higher standard than Amateur equipment. Actually, in Canada, amateur band radios do not need any IC certification although we often see Yaesu radios certified up RSS 215 (analogue scanner receivers. In the States, even amateur radio equipment must be certified by the FCC before it can be legally sold.

Most often nowadays, VHF land mobile service radios such as the Tait, span  the entire VHF range from 138 to 174 MHz and therefore easily cover the two metre amateur band, 144 to 148 MHz. And it is certainly permissible to program and use these radios in the amateur band providing the user is a certified amateur operating in the amateur service with a minimum of Basic qualification and communicating with other duly qualified amateurs.

Indeed, such radios could also be programmed outside the amateur band on duly authorized frequencies such as the SAR national frequency or other agencies frequencies providing written authorization is provided and providing the radio(s) in question are properly licenced either as part of a fleet or individually by Industry Canada and licenced is renewed on an annual basis. In order for radio equipment to be licenced in the land mobile service, it must be certified under RSS 119. In such cross service programming of radios, the amateur frequencies should not be included on the mobile or portable radio licence application. See RSS 119 at:

http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01063.html

Now it may be, that some (older) land mobile equipment had to be hardware "hacked" into making them tune the ham band. Some equipment was designed and sold with "frequency splits"… for example, Motorola VHF radio model xyz, may have been sold to cover 136 to 150.4 MHz while another split version of the same radio covered 150.0 to 174 MHz. And sometimes, if the radio was not in the right split range for the ham band, a little hacking into the front end pre-selector or VCO or otherwise was necessary to "tune the radio" for enough performance or frequency lock for satisfactory operation in the 2 metre ham band. One may argue, I guess, that that should only be done by a technically competent "Advanced" certified ham. But clearly, that would only be a very far right interpretation of the rules. And of course, there is no such interpretation circular given to Innovation, Science and Economic Development Canada officials if you asked them.

Again, Basic only qualified amateurs should be perfectly within the rules to use and even program radio equipment that is inherently designed to span the entire VHF range.







Sunday, November 25, 2018

Restoring A Rusting Old Tower



A BIG Project!

Eight years ago I received a free tower and rotator. I’ll write about the rotator in another installment but I’ve since discovered that some ‘free’ ham gear is like being given a free dog… you have to be aware of the hidden costs.

I had never had a tower but always wanted one. I’d been satisfied with my Carolina Windom, an off-centre fed dipole at 25 feet off the ground, that let me use most HF bands right up to 80m. It served me well, and still does but greater involvement in contesting and the desire to move up to a more directional antenna encouraged me to make the move.

Fortunately I have a wife who is also a ham, though not particularly active, but she knows the thrill I get when working a new country or breaking through a pile-up. She was supportive in my quest. Coincidentally I also had to replace the deck on our 30 year-old house. That provided another incentive to get the project started and find the right location. Our old laundry line was accessible from the deck at a corner of the house. The new deck, with glass panels around it would no longer allow this so the new tower would have to do double-duty as the anchor for the clothesline as well. I decided that it would be a light-duty tower as I didn’t have the space for a full-size tower, and I wanted to keep peace with my neighbours. 

I spread the word among my fellow club members that I was looking. Pretty soon an offer came in of five ten-foot sections of light duty tower. I picked them up and it was immediately evident that some work would be needed before they would be safe and usable. Thick rust had eaten though much off the galvanized surface. Several of the cross-member welds had broken and one section was noticeably bent. I knew my wife wouldn’t be pleased.




Over the next several days I spent time washing down my new acquisition, which had evidently spent time behind someone’s shed, judging by the weeds, caked mud and dead critters in and outside the tubing. I also spent some Internet time researching whether I could revitalize this tower and how to go about it.

My daughter-in-law manages a paint store and was able to provide me with some technical advice on surface preparation and coatings. I knew I would have to paint the sections for my wife to accept them right outside her kitchen window. Colour would also be a factor.

I bought two brass wire wheels and some emery paper and set to work to clean off as much loose rust as I could with my power drill. It worked well and a day later I was done. Based on my Internet findings, and helpful reviews by previous users, I tried three products to tackle the remaining rust. From left to right on the photo below they were Permatex brand ‘Rust Dissolving Gel’, ‘Evapo-Rust’ by Rust-stop Canada, and Rust Check brand ‘Rust Converter’. All were applied according to the provided directions and they performed their intended function. The gel, being thicker, clung to the parts better but was much slower and required a lot of re-coating to keep working. The other two products were thinner and more difficult to keep in place, but they produced faster results. If these were small pieces that could be submerged it would be no contest but keeping to a short section at a time and using a paint brush to keep the area wet with solution clearly showed the Evapo-Rust product to be the most suitable, and the fastest. It also appears to be the most environmentally friendly of the three, though I wouldn't recommend doing this job on your lawn, as I started to do. Yes, the grass did eventually grow back.





The surface was now free of rust and, after another scrub, was ready for inspection. I looked closely at each cross-tie and at every weld. Suspicious ones were marked. Several were obviously cracked or already split. With the assistance of Fred Orsetti VE7IO, the welds were repaired. I was ready for paint!

I would have used an oil based primer and top-coat but my expert advised me against it and she was correct. According to the product sheets for such coatings, it is not recommended that you use an oil based product on galvanized surfaces. The paint will release and peel off after a time—and I didn’t fancy the thought of doing this again in a couple of years. There are special coatings available in a spray can specifically for galvanized metal but they are quite expensive with low coverage, exacerbated by the necessity to get inside and out and into all the nooks and crannies around the welds. I decided a brush was the better applicator for that job.

We (read in wife-approval mandatory) decided the least noticeable colour on our wooded lot would be a camouflage green. As a result of my ‘colour-Googling’ I had actually suggested a multi-colour camo paint scheme but that was vetoed as being too ‘military looking’, and so the appropriate latex primer and top-coat were tinted. It took exactly one litre each of primer and top coat to paint the five sections twice, with extra coatings on the welds. I used an air sprayer on the legs for the final coat.




Next came even tougher work. I had to remove a section of my cement patio to make the appropriate foundation and dig a big hole. There were brackets available that could be surface mounted but I’m a ‘belt and suspenders’ kind of guy and I wanted this thing in a block of concrete. I used 3 thick reinforcing rods and placed the first tower section over the top.



If guys are not used, the tower manufacturer recommends fastening a section to the house as high up as possible, in my case that was just near the top of the 2nd section. I visited my local scrap yard and purchased some heavy-duty angle aluminum by the pound. I cut pieces to make an equilateral triangle and bolted one to the top plate of the house, running two arms to adjacent tower legs where they were secured by U-bolts. It’s steady as a rock. I used stainless steel hardware for all the section to section connectors in case I ever want (or have to) take it apart. That time is approaching as I have completed a rebuild of a rotator and HF yagi that will go up the following spring.

It has now been over 7 years and the tower shows no signs of either rust or paint failure through hot summers, cold winters and deluges of rain. It was a lot of effort but I’m pleased I did it. Even with my Carolina Windom centered at the top of the tower, much higher than before, I’m getting much more activity across all the bands. 



The sections above the roof blend in nicely with the trees. The final touch was to place flower baskets on the rungs at each level. My XYL now refer to it as the ‘Tower of Flower’ and surprise… the neighbours even say it looks good.

~ John VE7TI



Friday, November 16, 2018

A Triplexer... What is that?


Three Transmitters, One Antenna or Vice-Versa


You have probably heard about triplexers but are not sure what are they. Here is a simple explanation.

A triplexer is a device that allows 3 transmitters to share one antenna. The transmitters have to be on different frequency bands and the antenna needs to tune 3 bands. A good example is during a contest: 3 operators working with 3 transmitters one on 20m, second on 15 meters and third on 10 meters and the antenna is a 3 band Yagi 20-15-15 meters.
Inside a triplexer are filters that prevent power from one transmitter being routed to second transmitter and so on. 





A triplexer can also work backwards – it enables use of 3 different antennas with one radio. Here is an example:




A triplexer might not have enough attenuation to prevent strong signal from other transmitters from entering the receiver input. This could damage the receiver’s front end. Therefore extra filters are used:



More on this topic in the next Communicator... here December 1st

~ Les Tocko VA7OM



CQ CQ CQ

Rebuilding a Ham Rotor

A bit of patience and some time...  Following up on my article on rebuilding/refinishing a tower ( https://t.co/WY4VtD82kT ) I promise...

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