Ugly Heavy Duty Portable Tunable HF Antenna Mount

CameraZOOM-20170122110617682   Being a relative newbie to antenna mount creation I fully realize there are a lot of things that this particular cobbled together portable HF antenna and mounting system is not.  My objective was NOT to create a well engineered mounting system that I could manufacture and sell.  Why?  I am a humble bean-counter that was bored enough to study enough to pass my ham radio licenses.  Rather, I had some spare parts from prior radio projects, an old tire replaced on a boat trailer and an idea that combined an ARES / RACES cached set of mounts and antennas PLUS a shelving project plan I saw in Handyman magazine that used commercial pipes and flanges for the supports.  I priced that out for my ham shack shelving and found I could use other materials for far less cost.  If you watch Dave Ramsey on YouTube or such – you will see a really nice set of shelves.  Very helpful to envision what is possible, thank you very much!  When I thought about this project – these various components just all came together to form this system.

Before I lose you – here are it’s strengths – and then the nitti gritty details of how to build it and how it operates:

Portable.  This system breaks down and unscrews to components that can fit in a car.

*  Sturdy.  I suspect, but am not sure, that this will survive un-guyed to somewhere around 90 mph.  I have tested this system during the NW Lower MI winter of 2017.  It endured high winds of around 50 mph, an ice storm, snows, rains, accumulating snows, melting snows, direct sunlight, very cold temps, etc..  Why use a heavy tire when some elegantly designed aluminum tripods are available that are much lighter to transport long distances?  Because my objective was to have this mount survive an entire winter.  The tire sits nicely atop snow.  A tripod may not.  The tire is also heavy – that provides more resistance to tipping.  I had to move this a number of times during the winter for snowplowing purposes, etc..  The tire concept served my purposes well.  I know for use on an apartment deck or backpacking long distances an ultra-lightweight tripod would probably be better.  If you want to have something you can assemble and see it “still standing” at the end of the deployment – weather that’s a week or a year – then this rugged mount fits the bill!

*  Quickly Deployable.  Once constructed (welded, etc.) this can be taken from car to field- ready deployment in…  minutes.  My guess is 10 or so although I did not put a stopwatch to it.

*  Reasonable Cost.  We replaced some tires on our boat and had some extras in the garage.  I would not use them for long trips with the trailer, but for this purpose they were just fine.

*  Tuneable – With or Without A Tuner!  The Wolf River Coil has a tunable element – a plastic sleeve if you will.  This sleeve anchors a piece of strong spring steel that is “bent” into a V notch.  That sleeve can be loosened with a plastic bolt and the sleeve can be slid – with some force – up and down along the coil.  It takes, for me, a pretty good amount of force to move it.  Their website gives approximate number of “clicks” needed to tune the coil, to a given band.  With the 102” whip I was able to work 160 – 20 meters.  Tuning will be discussed below.  Other bands are possible with shorter whips.

Changeable.  The top flange was used so that different mounts for different antennas could be quickly deployed.  Unscrew the current one and screw a new one on, reattach the radials (future improvement?) and off you go!

*  Enhanceable  This project could be taken in several new directions, depending on your technical prowess with automotive mechanics, etc..  For example – if I knew how and had the time and funds for it – it would be really cool to have a matched set of these.  A phased array or ground mounted beam comes to mind.  Or – Have a light weight axle connecting the two of them.  Have a little platform that would sit on the axle and would have the rest of the components fastened to it – with bungee cords, ropes, straps, etc..  Have a light weight post and handle attached to the axle.  This could be driven to a woodsy location, assembled as a cart, then pulled by hand for a good distance over rough terrain for remote deployment.  Don’t forget the battery, of course!

The basic concept for this system was “stolen” from Outagamie County ARES / RACES.  Probably not much of a problem because I altered the design substantially and I was the Emergency Coordinator there for 4 years.  Also, I am publishing my design as a give-back to new hams, ARES / RACES members, preppers, etc..

Here are the details:

The base for this unit used a tire and wheel (tire inflated).  The tire is relatively small for a small boat trailer.  Larger tires add more weight and stability and more ability to wheel through rougher terrain.

Stability could be enhanced, also, by use of a spike of some sort or guying or tying down to decking or sides of a truck, etc..  One thought is to use a ground rod or two driven through the wheel holes at angles.  That works – unless the ground is frozen.  Other ideas include cement blocks or bricks, although that makes distant manual transportation more problematical.  A log or two in the woods might also work.  Perhaps pack a survival saw or hatchet in your kit for this deployment.  In winter, ropes attached to light metal boxes could be used.  Burry them below enough snow and you have anchors.

CameraZOOM-20170107100553343    My brother-in law is a pretty good welder and was kind enough to volunteer to spot-weld this for me in a few places.  My guess is that a shop probably wouldn’t charge much for doing that.  If you batted your eyelashes at them and told them your ARES / RACES team was going to help save the world when the zombie apocalypse happened they might do it for free as a charitable act.  Make sure to say thank whatever way it goes down.

CameraZOOM-20170107100813598    The main vertical components of this – and there are certainly other ways to do this and other materials that can be used (ARES used primarily wood) – are industrial pipe components purchased at a local hardware store in a small town.  In this picture, a flat bottomed threaded flange is being welded to the wheel.  We discussed the amount of welding needed.  In this instance I only was going to use a 102” CB stainless steel whip and the stress on the welds would be minimal.  With that said – consider this step carefully if you use other components.

The industrial pipe section is threaded on both sides.  One side is screwed into the flange attached to the tire.  Another flat topped flange is screwed to the industrial pipe on the top side.  This top flange is the base of the mounts.  I am planning on using several of these with different types of antennas.  This one, HamStick type single band antennas, perhaps a small beam, etc..  We have even discussed hauling this “little beast” to the top of our relatively flat section of roof over one part of our home to gain some height.  Probably not going to do that but the thought briefly crossed my mind.

CameraZOOM-20170122110633848    In my use of this system – I attached LMR-400 coax and ran 100 watts from a Yaesu FT 857d radio.  Frankly, not having a ground was problematical.  To enhance the system in several ways I added two sets of ground radial and an RF choke at or near the antenna and grounded the RF choke.  After I did these things I was really pleased with the ability to tune a wide range of bands and the performance of the receiver and transmitter.

As to the ground radials.  The first thing I tried was a set of spare ground radials that I had from our Gap Challenger DX antenna that is shrink wrapped and stored in the rafters of our basement.  They are about 17 feet long and are the nice sturdy yellow radial pictured.  Acquired from Gap Antenna.  Look them up on the web.  Good guys to work with!

The other thing I did was to shop for some least cost locally available wire for ground radials.  What I found was doorbell wire.  Thin and so not broad banded.  But affordable!  I can just see the eyeballs rolling now…  Cost per foot was low and they were 2 to a length – twisted.  I cut them to I think a 1/2 wave on 40 meters.  How to untwist them?  I have a nasty habit of saying to myself, “This can’t possibly be THAT bad – I’l just…” do it manually.  Well, that worked to a point.  I relatively soon realized it was going to become impractical.  I thought I remembered a video of someone using a cordless drill to untwist something like these.  I ran into the house, fired up YouTube and sure enough – found a video, watched it, grabbed my drill and got back to work.  There are some things in ham radio that are just amazing to some people.  My first clear mobile DX contact was one of them.  This use of the drill was another!  Pretty slick I thought…

I did not bury the radials although I read somewhere this can help lessen noise.  I did notice changes in noise as ground wetness changed and as different textures of snow came and went.  For emergency communications purposes, they should work just fine just laid out on top of the ground.

One set of radials was attached, in the picture below, to the coax connector.  I think this part was like $3 – $4 from Amazon.com.

CameraZOOM-20170114103802192    CameraZOOM-20170122110617682

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The black horizontal bar seen is a commercially available trailer hitch mount.  This fits into the square trailer hitch brackets seen on larger hitches.  It slips in and a pin of sorts holds it in.  It could be used there with these same radials if:

*  You don’t care about a large portion of your signal being blocked by the back of the truck.

*  You don’t have to have the antenna in a location not accessible by the truck.  Inside an a building – even an apartment say.  Or a distant wooded location.

I went to the local hardware store and got some nuts, bolts, washers, and wing-nuts.  I drilled a hole through both sides of the black bar.  That was easier than I had feared.  The longer ground wires are stripped at the end and wound around the bolt between the black bar and the washer.  This could be enhanced by scratching off the black enamel finish on the black bar.  I suppose lugs could be installed on the ends of the wires as well.

The black bar, by the way, is simply U-Bolted down through two of the 4 holes in the flat side of the flange.  No drilling was required.  Sometimes ya get lucky, right?

In the photo above you can see the Wolfe River Coil attached to the trailer hitch mount and the 102” stainless steel whip attached at the top.  Note that, while in development the antenna was off-center compared to the industrial pipe below.  This was later changed to improve stability.  It was pretty cold when I was working on this and I just wanted to see if it would work and fine-tune later if it did.

CameraZOOM-20170122110743156    Here is a closer look at the trailer hitch mount.  A few issues:

*  Not really too sturdy, although it works well for this particular install.  If this were in constant high winds or in constant motion – say in the back of a pickup truck or something or maybe on a towed trailer – I would have grave concerns.

*  Not really a huge concern, but the SO239 connector for the mount is annoyingly recessed.  This requires a little bit of additional awareness to ensure that the PL259 of the coax is securely tightened.

*  You don’t see any tapes, etc. to waterproof the connections.  That could be added.  This was tested as a “worst case”.  It worked.

*  There is a small washer below between the black trailer hitch bar and the stud mount.  This, quite disappointingly, rusted.  This can affect the grounding of the system and should probably be replaced with a stainless steel washer and enamel removed at the point of contact.

*  The mounting stud itself is small compared to the size of the antenna.  This could be reinforced.  A ball and spring could also be used instead.  That would provide additional adjustability flexibility.

TUNING:

CameraZOOM-20170122110801026    There are several ways to tune this antenna and mount system.  Here’s my original method.  I used the specs on the Wolf River Coil website to “click down” to the approximate band.  Then, when it was mounted mobile, I used my MFJ-269 Antenna Analyzer to tune the white collar to the nearly exact 1:1 match on the specific frequency I want to transmit on.  I then check the power out meter on the Yaesu FT-857d radio to verify that it is giving me a valid reading.  In my mobile mount it maxed out the power meter.  Here with all the losses I get about half scale with 100 watts.

In mobile practice, I was able to tune to 3.921 Mhz for the U.P. Net.  On Sundays, I found that exactly two clicks away was 3.967 for the WI State ARES / RACES Net for Sunday morning news and training.  I also found that rotating the collar clockwise or counter-clockwise would allow me to tune finer than a full click.  If you have the equipment and time in the field and will be operating on one given frequency or two close to each other – use that method.

The reason I constructed this mount in the first place was simply for personal use – to have a multi-band HF antenna for the home we moved in to in NW Lower MI over the winter.  We had a lot to do between moving, consolidating goods, mowing the golf courses, etc.  I only wanted a limited whip on it and not some larger grandiose structure – although that would be possible for other uses.

For use in the back yard, I decided to acquire an antenna tuner.  I purchased a LDG YT-100 antenna tuner.  This matches up with the Yaesu FT-857d radio and works really well – so far.  It is simple to use and plenty fast for my uses.  It also covers digital uses, etc..  It is designed to be used with an unbalanced input – i.e. – 50 Ohm coax.  The real reason I bought the tuner is because I envisioned (goal – not fantasy) a relatively large HF wire antenna or so in our property.  We have tall trees and plenty of room for that.  The wire antenna would follow in spring / summer.  This little project allowed me to get used to using the tuner.  Meanwhile I have acquired a 4 Legged Horse Fence Antenna for 80 meters.

In my use – there are two more ways to tune this system.  One is to use the most noise method and then apply the tuner.  Why not use this method?  Because it takes two people instead of one.  The radio is inside the house – or – needs to be brought out to do the tuning.  Another possibility is to backup the truck with the same radio and connect to that radio.  Both take time and are nothing but a hassle.  If you have a HT capable of tuning HF, then maybe that could be used…

My winter backyard method is to use the website to tune to one band.  40 meters usually.  I then use the tuner to fine-tune the system to that band.  Then you can start making really good contacts given the amount of metal that high in the air.  You CAN use the tuner to then operate on other bands – BUT – you are using the magic of the tuner and not the coil to do the tuning.  And that will probably never be as efficient as using the coil first and then the tuner.  But – it does work in a pinch.

Using 40 meters as my coil tuned band I have found that 40 meters and everything down to close to DC is great on receive.  If you really want to have a rag chew on 80 meters, then tune the coil to that and then use the tuner.  If you just want to listen, then staying on 40 meters and not retuning was just fine for me.

At night – this method makes an AWESOME commercial AM radio antenna.  It is also marvelous for shortwave radio reception – and that is all I am going to say about that.

CameraZOOM-20170114103831912    NOT REALLY part of the mount project – I did install a coax entrance into our home at the time of this test.  This took additional time to develop the entire system and get the coax connected up.  You can see my most trusted friend – VICE GRIP!  It is firmly clamped, holding the ground rod, ground wire and ground strap from the mount together.  After initial testing, tuning and radio use testing, this was removed and redone as it should be.

An addition tip.  I did not use any lubricants even though I was told I should.  Granted, this could prevent corrosion / rusting from keeping the industrial pipe and the flanges from being unscrewed at a later date.  I did make sure to twist them back and forth every couple of weeks and they survived the winter.  One could use WD40, some forms of grease, etc..  One caution!  If you ever intend to use the mount as part of the ground – consider if the grease or whatever will get in the way of effective grounds…

Until next time – stay radio active!

73,

 

Jon E. Kreski – AB9NN

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