Restoring a rusty old tower (revisited)

Like being given a 'free' dog...

A BIG Project!

(from The Communicator - August 2013)

Three years ago I received a free tower and rotator. I’ll write about the rotator in another instalment 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 if I attempted to place that within view.

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 adjoining photo 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 crosstie 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 small 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. 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 aluminium 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 in the spring.

It has now been two years plus and the tower shows no signs of either rust or paint failure. It was a lot of effort but I’m pleased I did it. Even with my Carolina Windom centred 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. We now refer to it as the ‘Tower of Flower’ and surprise… the neighbours even say it looks good.

 ~ John VE7TI

A Pop-up Ham Sale

 

April 29 at our Training Site

5746 142 Street, Surrey

Surrey Amateur Radio Communications will be holding a parking lot sale next Saturday April 29th (weather permitting) to dispose of a large quantity of surplus ham equipment. 

Lots to choose from!

 
Items for sale include HF and mobile transmitters, receivers, transceivers, antennas, rotators, test instruments, coax and other cable, swr and power meters, power supplies, tuners, scopes, dummy loads, misc. accessories etc. We also have a utility trailer for sale. 
 
The sale is at our Ops & Training Centre 5756 142 St. Surrey, BC. from 11 am to 2 pm.  No early birds please (Map link: : https://what3words.com/daunted.rarity.parrot)

 
SARC/SEPAR members and non-members are also invited to set up a table or sell personal items from their vehicles. There is no charge for this.
 
Before the event, you may also wish to join us for our club breakfast at Denny’s Restaurant 6850 King George Blvd between 7:30 and 9:00 am.
 
Questions? SARC@VE7SAR.net

Here is a partial list

See you there.

 

~

SEPAR Mobile Cruise-In

 Come show us yours... 

Many Amateur Radio licensees have home stations where the hobby is practiced for fun, contacting similar stations all over the globe, but the hobby has a serious side as well. We provide emergency communications where all other systems, such as cell phones or even radio towers fail. Many of us have mobile stations (in compliance with distracted driving regulations) that permit us to operate wherever and whenever. Mobile Amateur Radio is not restricted to cars and trucks but bicycles, even pedestrians and equestrians. This type of broad-based community availability requires no commercial infrastructure, hence the slogan: “ Amateur Radio works when all else fails”. This has been shown time and again all over the world.

SEPAR would like to host a first ever event of its kind locally. We have a commitment from the Surrey Fire Service and I expect that support from our contacts at the Surrey RCMP (or Surrey Police Service)  to judge the entries.  Prizes will be awarded for the neatest installation and the most bands covered.

The idea for this local event originated with the Portage County Amateur Radio Service (PCARS), a Wisconsin group who have been doing the Mobile Cruise-In for twelve consecutive years.  Their turnout varies with the weather, but in past years they've had 50 or more entries. In addition to the entrants and Amateur Radio spectators, we welcome members of the public to stop by and check out the goings on. They say that it's a great way to generate some exposure for Amateur Radio and our emergency programs.

We appreciate the support of the A&W restaurant at that location but, if you are not an A&W fan, there are several other refreshment options adjoining the same large parking lot.

So polish up your mobile rig, dust off your Grab ‘n Go kit and come show it off at  the ‘Cruise-In’

August 25: The post event video is now available at: https://youtu.be/VxwvYtPwaGU 

Repair of an IC-208H head unit

Icom to the rescue...

It happened in a moment of inattention… I dropped my mic and the hanger caught the screen of the head unit of my Icom IC-208H. The crack was obvious but I thought I could make it less so. I applied some super glue, hoping it would seep in so that I could then polish it out. It didn't.

I found the service manual on-line and discovered that the repair would be relatively easy. But this transceiver is 16 years old, and unlikely a replacement part would be available. I’m a big Icom fan. My first transceiver was an Icom and I’ve owned several since with great success. I once had to send a Yaesu for repair. The nearest service facility was in California and it took just under a year before I got it back. We’re fortunate that Icom Canada has a service depot locally. Staff has always been very accommodating… like when I lost a knob from a handheld. I received a replacement within a day.

I called the depot  expecting to be disappointed. Surprise! The part was in stock, immediately available, and only a couple of dollars.

I remain an Icom fan. The gear works well, is well constructed, and is well-supported - even after years of use.

~ John VE7TI

 

GMRS in Canada

There are major differences from US regulations 

Following up on a recent blog post by Bob Witte K0NR [https://www.k0nr.com/wordpress/] with the Canadian perspective.

There are big differences in GMRS rules between the US and Canada. If you understand the rules, you’ll  understand what you need to look for when purchasing GMRS radios, and you’ll understand what channels to use to get better range. And you’ll understand why you could get in trouble for using some US radios that are not approved for use in Canada – and vice versa.

Radios must be approved in the country of usage

Every GMRS radio has to be approved by the authorities of the country where you will be using the radio –  Industry Canada (IC) and the FCC in the US. There are also rules for usage. If the radio does not have an IC number, it’s not approved for use in Canada. If the radio does not have an FCC number, it’s not approved for use in the US.

Industry Canada has a lot of information here.

GMRS – FRS with more channels, and *maybe* more power

GMRS is an evolution of FRS that is compatible with older FRS radios on the FRS channels.  But there are significant differences between Canada and US regulations.

Licensing, power limits, antennas and repeaters

In Canada, GMRS users do not require a  license. In the US, radios above 0.5 watt require a GMRS license. In Canada, you’re limited to 2 watts power on the GMRS and combined GMRS/FRS channels, and 0.5 watts on the GMRS channels. In the US, if you have a license, you can go to 5 watts on the GMRS/FRS and GMRS channels.

Repeaters. There is no provision for legal usage of GMRS repeaters in Canada. In the US, licensed users can us GMRS repeaters and GRMS radios with repeater capability.

Antenna. In Canada, the antenna must be fixed on the radio. It cannot be removed, and it is illegal to replace or modify it. In the US, licensed users can change the antenna.

What’s the range of my radio? How is it affected by power?

Most of the radios you buy in big box stores in Canada and the US are designed to be legal for unlicensed usage in both US and Canada – which means you will be limited to 0.5 watts, a quarter of the power you’re allowed to use in Canada. The ranges they advertise are generally ridiculous, varying from 20 km to 80 km (50 miles).

Finding the power rating for the radio is not always simple. Most manufacturers don’t tell you. We’ve checked the packaging, manuals and web sites for the two biggest manufacturers, and it was either not there or very difficult to find. We’ve never seen a radio rated for the full 2 watt maximum. The closest we’ve seen is 1.92 watts, advertised with a 80 km/50 mile range. We’ve seen 1.6 watt advertised with a 50 km range. So everything is approximate.

Another hint is the batteries. A 0.5 watt radio might have a battery compartment for 3 x AAA batteries. A radio with 1 watt, 1.5 watt or just under 2 watts might have 3 or 4 AA batteries to handle the extra load.

- John VE7TI

 

Just what is bentonite?

 and why do I need it?

The ‘OTC Report’ (in the September-October Communicator at https://bit.ly/SARC21SepOct) mentions bentonite as an aid to achieve better RF grounding… but what exactly is this stuff?

In geology, the term bentonite is applied to a type of claystone composed mostly of montmorillonite. It forms by devitrification of volcanic ash or tuff, typically in a marine environment. This results in a very soft, porous rock that may contain residual crystals of more resistant minerals, and which feels soapy or greasy to the touch. However, in commerce, the term bentonite is used more generally to refer to any swelling clay composed mostly of smectite clay minerals.

Sodium bentonite expands when wet, absorbing as much as several times its dry mass in water. Because of its excellent colloidal properties, it is often used in drilling mud for oil and gas wells and boreholes for geotechnical and environmental investigations. The property of swelling also makes sodium bentonite useful as a sealant, since it provides a self-sealing, low permeability barrier. It is used to line the base of landfills, for example. bentonite is part of the backfill material used for waste isolation. Various surface modifications to sodium bentonite improve sealing performance in geo-environmental applications, for example, the addition of polymers.

Here in BC, bentonite was installed in slurry walls in North Vancouver, Quesnel and Williams Lake to stop the migration of railway diesel contamination to adjoining properties.  It was also used it to seal up abandoned environmental monitoring wells, and is  used as pond liner to stop the water from seeping away.

Sodium bentonite can be combined with sulfur as fertilizer prills. These permit slow oxidation of the sulfur to sulfate, an important plant nutrient, and maintain sulfate levels in rainfall-leached soil longer than either pure powdered sulfur or gypsum. Sulfur/bentonite pads with added organic fertilizers have been used for organic farming.

The main uses of bentonite are in drilling mud and as a binder, purifier, absorbent, and carrier for fertilizers or pesticides. As of around 1990, almost half of the US production of bentonite was used as drilling mud. Minor uses include filler, sealant, and catalyst in petroleum refining. Calcium bentonite is sometimes marketed as fuller's earth, whose uses overlap with those of other forms of bentonite.

Bentonite is used in a variety of pet care items such as cat litter to absorb pet waste. It is also used to absorb oils and grease.

What you should know when using ground enhancement material

Under almost all soil conditions, the use of a ground enhancement material will improve grounding effectiveness. Some are permanent and require no maintenance. You can use them in areas of poor conductivity, such as rocky ground, mountaintops and sandy soil, where you can't drive ground rods or where limited space makes adequate grounding difficult with conventional methods.

Bentonite is used to lower the resistance to earth by providing ground enhancement effectively reducing the resistance between the soil and earth electrode (such as copper earth rod or earth mats) by retaining moisture. This inherent ability to absorb and retain rainwater increases the electrical conductivity of the earthing compound in positive correlation to local climatic conditions, specifically average rainfall levels. Typically, the compound has a 3 ohms.m resistivity level – Bentonite compound is a cost-efficient material for backfill of earth electrodes and improving performance when it is physically impossible to drive the earth rods deeper and where challenging ground conditions exist such as rock, granite, etc.

Chemical treatment or backfilling of the soil in close proximity to the location of an underground earthing electrode is an established and traditional method of lowering ground resistance for substation earthing on high resistivity ground – such soil backfilling for electrical grounding improvements is commonly used.

There are several kinds of ground enhancement material available. But use care when choosing the material. It should be compatible with the ground rod, conductor, and connection material. Some options include bentonite clay, coke powder, and specially engineered substances.

Conduction in bentonite clay only takes place via the movement of ions. Ionic conduction can only occur in a solution, which means the bentonite clay must be moist to provide the required resistance levels. When bentonite clay loses moisture, its resistivity increases and volume decreases. This shrinkage results in a discontinuity in the contact between the bentonite clay and surrounding soil, which further increases system resistance.

A noncorrosive low-resistance enhancement substance is a conductive cement that you can install wet or dry. Depending on the substance, it will not leach into the soil and meets EPA requirements for landfill. The railroad and utility industries have successfully used this material. When installed dry, it absorbs moisture from surrounding soil and hardens, retaining moisture within its structure. When used dry, no mixing is required, and you achieve maximum efficiency in a matter of days. This is because it absorbs enough water from the surrounding soil. You can also premix it with water to a heavy slurry. You can add this to the trench containing the grounding conductor or use it around a ground rod in an augered hole. The material binds the water into a cement making a permanent, highly conductive mass.

Some products offer a test-proven resistivity of 0.12 ohm-m or lower, compared with 2.5 ohm-m for bentonite clay. Unlike bentonite clay, the cement-like material does not depend on the continuous presence of water; nor does it require periodic charging treatments or replacement.

An ideal ground enhancement material should not require maintenance. When designing or installing a buried grounding system, look for materials that do not dissolve or decompose over time, require periodic charging treatments or replacements, or depend on the continuous presence of water to maintain conductivity.

~ Internet sources including:

https://www.powerandcables.com/product/earth-tapes-rods-bars-copper/bentonite/ and https://youtu.be/hHtIYboE8NE

 

A Vector Network Analyzer

Once only a lab instrument, today the prices are affordable for most hams.

The great thing about amateur construction projects is that it provides opportunities to learn about new things.  I was curious about a device called a VNA (Vector Network Analyzer) after Les Tocko VA7OM showed me his home-built VNA which he was using to tune up the triplexer, diplexer and bandpass filters currently under construction.   Here is what I learned from a Tektronix website.

Vector Network Analyzers are used to test component specifications and verify design simulations to make sure systems and their components work properly together.

From mobile phone networks, to Wi-Fi networks, to computer networks and the to the cloud, all of the most common technological networks of today were made possible using the Vector Network Analyzer that was first invented over 60 years ago.

R&D engineers and manufacturing test engineers commonly use VNAs at various stages of product development. Component designers need to verify the performance of their components such as amplifiers, filters, antennas, cables, mixers, etc.

Above: The NanoVNA, a very affordable instrument
Below: It can be connected via USB to your smart device or computer for
a larger screen and many additional functions

How does a VNA work?

A Vector Network Analyzer contains both a source, used to generate a known stimulus signal, and a set of receivers, used to determine changes to this stimulus caused by the device-under-test or DUT.

The stimulus signal is injected into the DUT and the Vector Network Analyzer measures both the signal that's reflected from the input side, as well as the signal that passes through to the output side of the DUT. The Vector Network Analyzer receivers measure the resulting signals and compare them to the known stimulus signal. The measured results are then processed by either an internal or external PC and sent to a display.

VNAs perform two types of measurements – transmission and reflection. Transmission measurements pass the Vector Network Analyzer stimulus signal through the device under test, which is then measured by the Vector Network Analyzer receivers on the other side.

Examples of transmission measurements include gain, insertion loss/ phase, electrical length/delay and group delay. Reflection measurements measure the part of the VNA stimulus signal that is incident upon the DUT, but does not pass through it. Instead, the reflection measurement measures the signal that travels back towards the source due to reflections.

It sounds like every serious amateur experimenter should own one of these devices.  While most of the available devices are expensive lab quality instruments usable at microwave frequencies, many are affordable and suitable for amateur use at HF. 

Next month, we will feature an article describing Les VA7OM’s VNA and reflection bridge, and how he used them to tune up the triplexer, diplexer and bandpass filters. 

~ John VA7XB

   19-04

NOTE: We are currently offering a series on the practical use of the Nano VNA for Amateurs. See the 2021 Communicator issues on this blog.