Spring / Summer backyard tower project

[Rob_Walker]

Since I have all this spare time on my hands from self-isolation, I thought I would share my tower project with you as I go through the various stages.  Amateur radio is a new hobby for me and I'm treading on uncharted territory.  I'm thankful for the assistance I've received from Tom (VA3TS), Jeremy (VA3JL) and You Tube!  Learning by the seat of my pants is what I'd call it!

I have a small lot in Owen Sound close to the river.  Because I'm down the bottom of 10th street, I'm expecting city noise and the escarpment to be an issue.  To help mitigate this, I have a Wade DMX-40N 40' heavy duty tower that was dropped off last weekend in sections by TDL Canada.  The specs call for a 4' x 4' x 4.5' concrete base reinforced with concrete.  As soon as the weather clears up, I plan to hand dig this, or at least start it.  I have two other volunteers willing to help with the dig so that is a relief.

One of the obstacles I have run into before even starting is concrete.  Harold Sutherland Construction was a customer of mine before they were bought out by Walker Aggregates.  I had their concrete guy Mike Gowan stop by to see how we were going to get 3 cu. yds. of concrete in my back yard when the space between the houses is just under 10'.  We couldn't use a pump because of the utility wires.  This  left us with the conveyer option.  However, the conveyor was short 15' from the hole so we would still have to hand bomb with a wheel barrow.

All that changed.  Harold Sutherland Construction redi-mix division is not an essential service unless you had a permit prior to Doug Ford's list of essential services.  As a consequence, they can't supply me and are struggling themselves to stay open.

Unless there is a change, my backup plan is to do this with a rented 9 cu. ft. mixer from Sunbelt and 160 bags of concrete from one of the local building suppliers.  This is a lot of cement to mix and I'm not a spring chicken anymore.  Once again, I'm grateful to have a helper or two that can help and and also practice safe distancing.

I will keep you posted.  Today I'm going to go pick up my TGM MQ-36SR quad cubical and Hy-Gain vertical I have stored in someone's barn.  At the very least this week, I would like to get these set up on temporary masts and tuned with my Rigexpert AA-220 Zoom, a toy I am really anxious to play with.  I was able to get my mast material yesterday from Elma Steel.  I got two 12' lengths of 2" galvanized with almost 1/8" wall.

73's to everyone!

[VA3TVA Tom]

Hi Rob.   I suggest, that you send an email to Tom TS about a week ahead of the work.  Many of us would be happy to come and help.  Even if only a couple hours, I'm sure it would be a big help for you.

[Rob_Walker]

Thanks Tom, that's very generous of everyone.

[Rob_Walker]

I am pleased to announce that I am now an official member of the GBARC community.  I went out to Tom's yesterday and wrote my exam.  I am now officially VE3RWY.  With a renewed sense of purpose, I took advantage of the nice weather today and made a start digging the hole for my tower.  I will have a helper with me on Monday and hope to have the dig completed before the rain this coming Wednesday.  I still plan to hand-bomb the hole with 66lb bags of concrete, but I'm also thinking there is a chance Ford might relax some of the closures which would allow Sutherland or Miller's to deliver concrete.  Here's a few starter pictures:







73 VE3RWY

[Rob_Walker]

Got the hole dug today.  The next obstacle is the cement.  There will be three pallets of bagged cement.  I need them delivered to the back yard.  Home Building Center said it's entirely up to the driver if he wants to drive on grass.  I can't have the cement left on my driveway because the 15 cu. ft. cement mixer won't fit.

Some of today's progress:

[VA3KOT John]

Welcome to ham radio Rob. I see you are planning to start off with a very big station. I don't have a tower myself; I prefer stealth antennas and that limits me to simple wires in the trees. I've done quite well with my simple antennas. I even QSOd (CW) with France on a short vertical and 25 watts in my backyard this week. Of course, the station in France had a 70 ft tower and a beam! Anyway, good luck with your project. If I can help without getting into trouble with the social distancing laws let me know.
John, VA3KOT
Owen Sound.

[Rob_Walker]

Thank you very much for reaching out John.  Are you in Owen Sound?  I'm at the bottom of 10th street with the escarpment to one side.  I'm hoping my location and the city noise does not work against me.

73 Rob

[VA3KOT John]

Thank you very much for reaching out John.  Are you in Owen Sound?  I'm at the bottom of 10th street with the escarpment to one side.  I'm hoping my location and the city noise does not work against me.

73 Rob

Rob, I'm on the west side just across the boundary in Georgian Bluffs on Park Street near Brooke. Bernie, VE3BQM, lives just down the same street. My details are good on QRZ.com. Noise is always a problem in urban areas. That's one of the reasons I like simple wire antennas. Vertical antennas pickup a lot of noise; my horizontal end-fed resonant wire (on 40m, 80m) is better and horizontal loops pick up least noise. Most radios can compensate for noise through IF (and sometimes AF) filtering so it shouldn't be a big problem. We are currently at the bottom of the solar cycle so HF propagation conditions vary between poor and fair. QRN (static) and QSB (fading) are much bigger problems than local electrical noise at the moment.

[Rob_Walker]

John, does a loop perform better the higher up it is?

[VA3KOT John]

John, does a loop perform better the higher up it is?

If any antenna is close to ground some signal is lost but, in some cases, other factors are improved. I have experimented with "Grasswire" antennas which are actually laid directly on the ground, with surprising results (read: http://f5ad.free.fr/Liens_coupes_ANT/G/K...0gazon.htm).

The general rule is to get an antenna up high; ideally a half wavelength above ground. However, that's impractical for the low bands like 80 meters. If a loop is at least 30ft up it will perform well on all bands.

There is a mode called NVIS (Near Vertical Incidence Skywave) that relies on an antenna being low. The propagation is almost straight up and, below the critical frequency (foF2), the signal will be reflected by the F2 layer in the ionosphere over an area up to about 400km from the transmitting station. Currently at our latitude NVIS only works on the 80m band by day and the 160m band at night.

GBARC has an 80m SSB net every Wednesday evening. I hope you'll join us when you're ready. Most of us communicate by ground wave on that net so antenna height isn't an issue.

Hope that helps Rob.

[Rob_Walker]

John, I had been researching EFHW antennas earlier because the layout of my backyard does not lend itself well to a dipole unless I use traps.  I think the EFHW uses a 49:1 transformer which might be a good learning project for me.  I could definitely run a 135' wire from my tower location to the back of my yard.

I have a small hand-held and have been listening in on the Wednesday net as often as I can.  I have listened in on other nets with my SDR and the casual conversation of like-minded hobbyists has an appeal.

73

[Tom VA3TS]

Hi, since you have a nice hole in the ground, this may be a good time to think about a ground rod. They say not to embed a ground directly in the concrete, but you can put the #6 in a conduit and bring that up through the pad... Greq VE3RQY can give you all the details about grounding... keep the top of the pad slightly above ground so no grass clippings etc will lay on it, round the corners if you can

https://gbarc.ca/grounding001.pdf

https://gbarc.ca/grounding002.pdf

73

[VA3KOT John]

Rob, a EFHW is a really good antenna to use. Mine is just that. I have attached some pictures to show you my installation. The near end is supported at about 18 feet on 5 sections of fibreglass camo pole (Princess Auto). The wire actually droops down the pole to the 49:1 transformer inside the grey plastic box on the fence. If your wire runs from your tower you may have to mount the transformer at the top of the tower to prevent the tower detuning the antenna.

A couple of notes about my 49:1 transformer:
1. I used a single ferrite core, FT240-43 (Mouser Electronics Kitchener, ON depot. Ordered online, delivered by Canada Post the next day). Some EFHW experts (e.g. Steve Ellington, N4LQ) recommend 3 cores. I never use more than 100 watts and have found that a single core works just fine. If you plan on using an amplifier you should probably use 3 cores.

2. I used thinner enamelled wire for the windings than is recommended. It was all that I had. I checked the current ratings and calculated that it should be easily sufficient for 100 watts. I have built another 49:1 transformer for use when camping in my trailer and used stiff insulated wire; it works too.

3. It is recommended that you use a high voltage capacitor across the coax input "to improve performance on the higher bands". I found that to be true for a 66ft wire (half-wave on 40m) but it made no difference for a 132ft wire (half-wave on 80m). Also, the Mouser part number for the part was no longer available when I tried to order it. My home antenna is 132ft (more or less) so I omitted the capacitor. My camping antenna is 66ft and, since I didn't have the right capacitor, I substituted a 4ft section of RG-58 coax, open at the far end, which has a capacitance of 25pF per foot. I tuned the length to get resonance on the 20m band - works like gangbusters.

The far end of my wire is supported at about 30ft on a tree at the back of my yard. I found that I had to adjust the length of the wire to get it resonant on the frequencies I like to operate. For me that is the CW portion of 40m and 80m. I bypass my tuner and get near perfect SWR. When I check into the GBARC HF net higher up the band I have to use my tuner. I also need to use my tuner for 20m. The antenna also tunes up OK on 30m - surprisingly.

One further note; the coax feeding the antenna MUST be perpendicular to the antenna wire for as far as possible. That's not just theory - I proved it in practice. I originally had my coax running parallel to the antenna (but about 20 feet away) and the induced RF in the coax braid brought RF right into my shack and caused tuning problems! If you run your wire from the top of your tower and bring the coax down the side of the tower you won't have that problem.

John, VA3KOT                

[Rob_Walker]

Thanks for the pictures.  Nice job on the transformer too!  I have watched all of Steve Ellington's presentations on EFHW antennas.  He did a presentation where he covered earlier 'wire type' antennas that I found very informative as a new comer.

If I put my transformer up my tower, do you think I should put a choke on the line?  I'm wondering if the coax would radiate or influence the resonance?  Of course, this is where all the fun comes - experimenting.  I like the way Ellington diagrammed his six configurations and took RF measurements at various parts of the coax and wire for comparison.

73 Rob

---

Hi, since you have a nice hole in the ground, this may be a good time to think about a ground rod. They say not to embed a ground directly in the concrete, but you can put the #6 in a conduit and bring that up through the pad... Greq VE3RQY can give you all the details about grounding... keep the top of the pad slightly above ground so no grass clippings etc will lay on it, round the corners if you can

https://gbarc.ca/grounding001.pdf

https://gbarc.ca/grounding002.pdf

73

Thanks for the tips Tom.  Yes I have been thinking of grounding and my plan was to put three ground rods in the soil and attach them to the tower legs with #2 copper.  I have a question:

Is is possible to connect my #2 ground wire to the ground rod below the surface of the lawn so I can cover the connection up?  I didn't know if I could use an anti corrosion compound on the connection then hide it under the dirt.  My concern was having objects sticking out of the grass.  If it is OK to do this, then I would add additional ground rods 6' away from the tower and connect them as well, below the surface.

73

[Tom VA3TS]

I'll send you Gregs email, he is the best one to ask...

[VA3KOT John]

Thanks for the pictures.  Nice job on the transformer too!  I have watched all of Steve Ellington's presentations on EFHW antennas.  He did a presentation where he covered earlier 'wire type' antennas that I found very informative as a new comer.

If I put my transformer up my tower, do you think I should put a choke on the line?  I'm wondering if the coax would radiate or influence the resonance?  Of course, this is where all the fun comes - experimenting.  I like the way Ellington diagrammed his six configurations and took RF measurements at various parts of the coax and wire for comparison.

73 Rob

---

Hi, since you have a nice hole in the ground, this may be a good time to think about a ground rod. They say not to embed a ground directly in the concrete, but you can put the #6 in a conduit and bring that up through the pad... Greq VE3RQY can give you all the details about grounding... keep the top of the pad slightly above ground so no grass clippings etc will lay on it, round the corners if you can

https://gbarc.ca/grounding001.pdf

https://gbarc.ca/grounding002.pdf

73

Thanks for the tips Tom.  Yes I have been thinking of grounding and my plan was to put three ground rods in the soil and attach them to the tower legs with #2 copper.  I have a question:

Is is possible to connect my #2 ground wire to the ground rod below the surface of the lawn so I can cover the connection up?  I didn't know if I could use an anti corrosion compound on the connection then hide it under the dirt.  My concern was having objects sticking out of the grass.  If it is OK to do this, then I would add additional ground rods 6' away from the tower and connect them as well, below the surface.

73

Rob, re putting a choke on the coax. Maybe but DO NOT PUT A CHOKE AT THE ANTENNA END. The feed point impedance of a EFHW is very high so the "common mode" current is very low. The braid of the coax acts as a counterpoise and if there is a choke at the antenna end it cannot do its job. I use a common mode choke at the radio end. My choke is 18ft of RG58 coax wound around a plastic pipe about 2 inches in diameter. You may not need a choke at all. My coax is 100ft long and I suspect that is enough to dissipate the small common mode current from a EFHW antenna.

By the way, many people suggest making a common mode choke by coiling a few turns of coax about 6 inches in diameter (so-called "Scrabble wound").  This is very bad practice. An effective choke has high impedance and that requires high inductance. If the choke is wound neatly it will have predictable and stable impedance.

[Rob_Walker]

According to the weatherman, Saturday looked like a good day to build a 2 x 4 frame around my tower base so I can suspend it over the opening above the hole.  Unfortunately, the rain got its way, but only after I had all my tools out.  Last week the rain percolated its way through the soil and my hole has 2' of water in it.

On a positive note, I may have a solution for my concrete.  Classic Concrete has done work for me in the past shoring up my foundation and pouring a concrete pad.  I talked to them Friday morning and they are not having any problems getting concrete.  Their office left me a message last night about getting concrete delivered this week so the 'pour' could happen much sooner than expected.  Apparently the concrete has to cure for 30 days before I can put the tower up.

73

[Rob_Walker]

Thanks for the pictures.  Nice job on the transformer too!  I have watched all of Steve Ellington's presentations on EFHW antennas.  He did a presentation where he covered earlier 'wire type' antennas that I found very informative as a new comer.

If I put my transformer up my tower, do you think I should put a choke on the line?  I'm wondering if the coax would radiate or influence the resonance?  Of course, this is where all the fun comes - experimenting.  I like the way Ellington diagrammed his six configurations and took RF measurements at various parts of the coax and wire for comparison.

73 Rob

---

Hi, since you have a nice hole in the ground, this may be a good time to think about a ground rod. They say not to embed a ground directly in the concrete, but you can put the #6 in a conduit and bring that up through the pad... Greq VE3RQY can give you all the details about grounding... keep the top of the pad slightly above ground so no grass clippings etc will lay on it, round the corners if you can

https://gbarc.ca/grounding001.pdf

https://gbarc.ca/grounding002.pdf

73

Thanks for the tips Tom.  Yes I have been thinking of grounding and my plan was to put three ground rods in the soil and attach them to the tower legs with #2 copper.  I have a question:

Is is possible to connect my #2 ground wire to the ground rod below the surface of the lawn so I can cover the connection up?  I didn't know if I could use an anti corrosion compound on the connection then hide it under the dirt.  My concern was having objects sticking out of the grass.  If it is OK to do this, then I would add additional ground rods 6' away from the tower and connect them as well, below the surface.

73

Rob, re putting a choke on the coax. Maybe but DO NOT PUT A CHOKE AT THE ANTENNA END. The feed point impedance of a EFHW is very high so the "common mode" current is very low. The braid of the coax acts as a counterpoise and if there is a choke at the antenna end it cannot do its job. I use a common mode choke at the radio end. My choke is 18ft of RG58 coax wound around a plastic pipe about 2 inches in diameter. You may not need a choke at all. My coax is 100ft long and I suspect that is enough to dissipate the small common mode current from a EFHW antenna.

By the way, many people suggest making a common mode choke by coiling a few turns of coax about 6 inches in diameter (so-called "Scrabble wound").  This is very bad practice. An effective choke has high impedance and that requires high inductance. If the choke is wound neatly it will have predictable and stable impedance.

Tom,

Do you leave the 6" coil on some type of form to keep it neatly wound?

[VA3KOT John]

Rob, it was I who posted the comment about where to place a common mode choke and how to wind it. It doesn't matter what diameter you wind the coil of coax; the key is to keep it neatly wound and use enough coax. I have attached a picture of mine (well, one of mine) so you can see how I did it.

John, VA3KOT    

[Rob_Walker]

Rob, it was I who posted the comment about where to place a common mode choke and how to wind it. It doesn't matter what diameter you wind the coil of coax; the key is to keep it neatly wound and use enough coax. I have attached a picture of mine (well, one of mine) so you can see how I did it.

John, VA3KOT

Thanks John.  That's what I had pictured in my mind.

[Rob_Walker]

Concrete contractor was around this morning and the pour is on for this Thursday.  I've completed the brace around the perimeter of the tower to keep it suspended over the hole.  The 2 x 4 brace on the tower will sit on top of the 4' x '4 form around the hole.  Shims will be required to get the tower vertical and then I may secure the tower to my deck with a couple of 2 x 2 braces to keep it from shifting.  The tower has a slight taper on this section.  I'll tape a 1/4" spacer at the 22" mark on my level and this will give me the proper offset to get this section plumb.

[Rob_Walker]

It was a wet day to pour concrete but we finally got it done today!

[Rob_Walker]

I got the gin pole up and the second section in place.  Although I don't plan to erect this on my own, I am going to attach a small hand-cranked winch at the base to make it easier for the ground helper. 

[Rob_Walker]

Rob, it was I who posted the comment about where to place a common mode choke and how to wind it. It doesn't matter what diameter you wind the coil of coax; the key is to keep it neatly wound and use enough coax. I have attached a picture of mine (well, one of mine) so you can see how I did it.

John, VA3KOT

John,

I read a good article on common-mode chokes.  The author built all these different air and ferrite core chokes then measured their impedance across different frequencies with a VNA.  That's a nice toy to have.  I have a customer in Cambridge that purchased a VNA for $80k to test the jackfields they make for the broadcast industry.

http://www.karinya.net/g3txq/chokes/

[Rob_Walker]

Two sections, three to go