Wednesday, September 20, 2017

Building Finally Begins on 2-M Antennas

220 VAC Y-Splitter for 6-M & 2-M amps
OK, Sports Fans, today I began building the 2-M antennas for the EME project.  YAY!

Two 13-L 144-MHz Yagis
But first, last night I built a "Y"-Splitter for my 220 VAC circuit.  I have two large 30-amp 220 VAC outlets in the wall of my shack but felt that it would be nice to have the HF amp plugged into one of them and the 2-M and 6-M amps "share" the other.  So, I built the splitter shown on the left.  Not a hard job but one that really needed to be done because the 220 VAC outlets are behind the operating table and very difficult to reach.  I have to pull out a 2-drawer file cabinet (which has the 6-M and 2-M amps on top of it) in order to reach the wall behind the operating desk.  Not fun!

Today I began the building of the 2-M antennas in earnest.  On the right you can see the shipping tube that contained the two 13-L InnovAntenna 144-MHz yagis.  The two 13el LFA2 2-M yagis were tendered to FedEx on June 29th (of 2016) and delivered to me on July 5th.  That's just 6 days and may have been much less if it wasn't for the weekend and the holiday.  I can't believe how fast InnovAntennas can ship antennas from England right to my house in Hurricane, WV. (Click on any photo to see a larger image.)

Elements Named
Element Center Markings
Once everything was un-boxed and inventoried, I was very pleasantly surprised.  Each end of every boom section was VERY plainly marked as "1", "2", "3", "4", "5", and "6."  Even better, since there were two antennas in the package, one set of booms was marked in Black and the other in Red.  NICE!

Next, each element was plainly marked as "RE", "DE", "D1", "D2", "D3", etc.  WOW!  No need to measure each element to find the correct one.  I am suitably impressed now.

Next I noticed that the elements have three marks near the center of each.  The manual indicates that these marks show EXACTLY where the center of the elements are and the two marks on either side, are spaced perfectly so that you can see them on the outside of the insulated element mounting brackets to know you have the element centered.  (This just keeps getting better and better!)

You can see in the photo on the left how those centering marks work.  When the top piece of the element mounting bracket is installed, the marks on the outside show up nicely so you can perfectly center each element.

The one complaint I have is that the actual written instructions for the antenna leave a good bit up to the builder to figure out on his own.  Luckily I had built an InnovAntenna 6-M beam two years ago and had solved some of those problems.  For example, there is a one metal element mounting bracket (all the rest are plastic) and no indication in the manual of where this goes.  From the 6-M antenna build I knew that this was a grounding bracket for the Driven Element loop.  Things like metric measurements, "P" clips, "RivNut inserts", "Jubilee" clips, and so on can cause some confusion but Mr. Google is your friend in these circumstances.  ("Jubilee" clips are "hose clamps.")

Marks Center Elements
The first thing I did was to assemble the first two boom sections.  The boom is square tubing and there are short pieces of round tube that slide inside the square tubing.  Those short pieces are plainly marked with tape that are numbered to match the pieces of the boom where they fit.  During manufacture, they were drilled in those locations so there is no problem in lining them up.  Yes, the short round pieces are also marked in Black and Red to denote the two separate antennas!

Never-Seez on Boom Joints
I coated the round pieces with Never-Seez and they slipped right in place.  Just as I had completed the first joint, Bob, W8OM, stopped by to drop off a contribution to VK9MA.  He noticed (as I had noticed) that the two square boom pieces were not perfectly aligned.  I said I could take one off and turn it around but Bob suggested I just loosen both and see if they would twist into place.  Yep!  That did it!  Bob's 'da Man today!

After the boom pieces were in place and supported on plastic saw horses, I began the process of installing the elements.  Since the elements were labeled and the centers were marked, this process proceeded at light-speed.  I just laid down one of the element clamp halves, placed the element on it, put the other half of the clamp on top, smeared some Never-Seez on the end of the metric Cap Bolts, and screwed the bolts (with an Allen wrench) into the "RivNut" inserts that were already installed in the boom.  Notice there was NO MEASURING to figure out where to mount the elements.  The "RivNut" inserts were already in the boom and I just had to screw in the bolts.  Easy-Peasy! 

 I found that I could pick up the two halves of the element clamp, two cap screws, the next element, smear on the Never-Seez and install the element in about 3-4 minutes.  It went SO fast I was getting dizzy!  I did double (and triple) check the element names to make sure they were in the right order as well as the centering marks.  Before completely tightening down the elements, I placed a large metal square alongside the boom and made sure the elements were square to the boom. 

Antenna #1 Nearly Completed
Never-Seez on Bolts
The driven element loop took a little longer to install as there is a C-shaped piece of tubing that slips into each side of the two DE ends.  This is held in place with "Jubilee" clips (hose clamps.)  And, the measurement from the inside of one "C-end" to the inside of the other is nominally 908mm.  I have a carpenter's rule that is marked in mm so that made this part of the project simple.  Adjusting the length of that loop by sliding that "C-piece" in or out is how the antenna is tuned.  This will need to be done with the antenna in its operating location at a later time.  I also used Never-Seez on mounting these "C-pieces" to insure good conductivity and prevent the metal from seizing over time.

There is also a "Truss" assembly that I need to construct and install to support the 26.26-foot length of the antenna.  Also, the boom-to-mast bracket needs to be installed.  This was not done today because it requires balancing the antenna and I'll leave that for another day.

So, today was a VERY good day on the EME project.  Antenna No. 1 is pretty much complete.  Building Antenna No. 2 should go a little faster now that I have a work flow established and all the necessary tools in place.  I carried the antenna around to the EME tower and just laid it on the roof so that the deer won't trample it in the yard.  Hopefully we get no strong storms before I finish the mounting - Hi!

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