Our HAM Station

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EME Station 2.0 Part 9 - H-Frame Assembly

Posted: 18 Aug 2020 02:35 PM PDT
https://stationproject.blog/2020/08/...art-9-h-frame/

M2 Antennas 2X2 2MXP28-32 H-Frame

The final major component to be assembled is the 2MXP28-32-2X2-3K H-Frame
which will support our four 2MXP28 Antennas. The H-Frame is one of the most
mechanically complex components in our EME antenna system so we began by
carefully studying M2s manual for this component.
Parts Identification, Inventory, and Preparation
H-Frame Parts Inventory

We also spent some time identifying and inventorying all of the parts. M2
supplied upgraded aluminum saddle clamps for our H-Frame. These parts
improve the clamping action between the components and also reduce stresses
on the fiberglass and other tube parts.
Truss Cable Parts Prep

We spent some time preparing the parts for the Phillystran Truss cables for
the Main Cross Boom and Vertical Risers. Prep included a drop of oil on
each of the clamp threads and some NOALOX Antioxidant Compound on the
turnbuckle threads. We also added stainless steel jam nuts to the
turnbuckles to lock them in place after installation.
Initial Assembly of H-Frame Sections
Assembled H-Frame Sections

We next mock-ed up the center section of the 3 Main Cross Boom in the
Elevation Rotator assembly to ensure proper fit and operation of the
Elevation Rotator.

With this done, we assembled the Main Cross Boom, Vertical Risers, and
T-Brace sections. This helped us to get all of the parts and hardware in
the correct locations and to become familiar with how all of the parts fit
together. We used a generous coat of NOALOX on all of the metal to metal
tubing joints to facilitate the assembly and to prevent corrosion from
forming at the joints of the metal tube sections. This sort of corrosion
can cause increased noise levels after the array is installed outdoors for
some time.
Main Crossboom Assembly
Cross Boom Truss Assembly

Next, the 3 Main Cross Boom and its support Trusses were assembled. We
carefully measured the assembly and marked the Center as well as the
locations of the Vertical Risers on the Main Cross Boom using a sharpie
pen. these measurements will make the final assembly of the H-Frame on our
Tower much easier.
Cross Boom Truss Details

The Phillystran Truss Cables and associated hardware were assembled and
adjusted next.
Vertical Riser Assembly
Vertical Riser Mock-up

We decided to Mock-up a section of the Vertical Riser center tubes and the
associated Vertical Riser Truss supports on the Main Cross Boom. This
allowed us to confirm that the final horizontal spacing of the Risers was
correct and to get the clamps associated with this part of the H-Frame
assembly properly oriented and squared.
Fiberglass Tubing Reinforcements
Reinforcement Bushing Design

The Vertical Risers use Fiberglass Tubes at each end to provide a
non-conductive mast for mounting the Antennas and their Truss Supports. The
Antennas we are using are large and will need to be tightly clamped to
ensure that they stay aligned and in place. The Antenna and associated
Truss U-clamps put a great deal of stress on the Fiberglass Tubes and they
can become distorted or damaged over time.

To prevent this, we decided to make a custom set of Reinforcement Bushings
from Polycarbonate Plastic. Bushings were designed to reinforce all of the
points on the Fiberglass Sections of both Vertical Risers where U-Clamps
will be used. You can see the full specifications for the bushings here.
W2SW Custom Reinforcement Bushings

Spencer, W2SW, owner, and founder of AntennaSys, Inc. made a beautiful set
of custom bushings for us. Spencer has an amazing machine shop at his home
and the parts turned out great and fitted precisely.
Reinforcement Bushing Installation

The Reinforcement Bushings were installed at the correct depth in each of
the Fiberglass Tubes and are pinned in place using small Stainless Steel
Machine Screws.
Assembled Vertical Riser

The final step was to assemble all of the parts associated with both
Vertical Risers. The risers were marked to indicate the location of each
Antenna Boom and Truss Clamp and the clamps were installed. The Phillystran
Truss Cables were installed in the Eye Bolts on the Vertical Risers.

As we did with the Antenna Truss Cables, we will wait to install the
Turnbuckles until the Risers are installed on the tower and balanced. This
will likely change the length of the Phillystran Truss cables.
Next Steps

The next step in our project will be the installation of our Elevation
Rotator, H-Frame, Antennas, Power Dividers,, MAP65 Housing, and Phasing
Lines on our EME Tower. You can read more about our EME station project via
the links that follow:

EME Station 2.0 Part 1 – Goals and Station Design
EME Station 2.0 Part 2 – Excavation, Footings, and Conduits for New Tower
EME Station 2.0 Part 3 – Phase Tuned Receive Coax Cables
EME Station 2.0 Part 4 – New EME Tower Is Up!
EME Station 2.0 Part 5 – Control Cables and Rotator Controller
EME Station 2.0 Part 6 – Tower Grounding System
EME Station 2.0 Part 7 – Building Antennas
EME Station 2.0 Part 8 – Elevation Rotator Assembly and Sub-System Test


If you’d like to learn more aboutÂ*How To Get Started in EME, check out the
Nashua Area Radio Society Teach Night on this topic. You canÂ*find the EME
Tech Night here.

Fred, AB1OC