3L SteppIR Spool Shaft Replacement 1/25/2018

On Saturday January 20, 2018, the spool shaft broke in the driven EHU (element housing unit) of my 3-element SteppIR yagi. On Monday I called Bart at SteppIR and he was very helpful in getting a replacement spool plate and EHU gasket to me quickly. The replacement spool comes already mounted on the base plate. On Thursday, January 25, I replaced the spool plate inside the EHU. Even though I made a similar repair in November 2015, I still used the instruction guide created by Pedro, EA1YO, showing the replacement of a sprocket shaft because much of the procedure is the same.

Procedure for Replacing the Spool Shaft and Plate

Please note the EHU shown here is a 2012 model and may not be exactly the same as others. Older EHU’s with gray shells do not have the circuit board and connector shown in these instructions. There may be other differences as well. Also, the term spool and reel mean the same thing and are interchangeable.

Step 1 – Remove the bullet from each end of tape. More

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Step 2 – Use your forefinger and thumb on the sprocket to wind the tapes from the element support tubes (EST’s) and back into the EHU so you can remove the spooled reels. IMPORTANT: MARK THE TOP OF EACH SPOOL “TOP” BECAUSE THEY MUST BE INSTALLED EXACTLY AS THEY WERE REMOVED OR ELSE THE SPRING INSIDE WILL NOT WORK.More

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Step 3 – Remove the plate assembly by removing the 3 nuts inside the housing. If the EHU contains a balun, you will need to disconnect the contacts before the removing the plate assembly from the EHU. More

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Step 4 – Remove the contact plate from the base assembly by removing the two nuts, screws and star washers shown in photo 8 using a Phillips screwdriver and 5/16″ nut driver. More

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Step 5 – Remove the stepper motor from the base plate by removing the four screws. More

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Step 6 – Turn the plate over and carefully remove the two-sided sticky tape holding the wires to the base plate (photo 12) then remove circuit board. More

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Step 7 – Begin reassembly by mounting the printed circuit board onto the new plate using the small screw and sticky tape. More

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Step 8 – Turn the plate over and insert the motor. Before installing the screws, place a very minute amount of Loctite into each of the screw holes in the motor (photo 17).  More

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Step 9 – Install the contact plate onto the base plate using the two screws and 5/16″ nuts. More

Step 10 – Install the two spools of copper tape onto the reel shaft. More

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Step 11 – With the spools in place on the shaft, install the washer and locking pin.

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Step 12 -This is where my procedure differs from Pedro’s. Pedro was able to maneuver the tapes under the contacts using a pair of tweezers. Since I had to remove the contacts in Step 3 because they were attached the balun, I slid the tapes through the contact plate as shown in photos 21 & 22, then installed the contacts on top of the tapes as shown in photo 23.

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Step 13 – The plate assembly is now complete. Reinstall the assembly back into the EHU using the 3 screws through the outer shell and reinstall the plug into the printed circuit board.

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Step 14 – Use the sprocket to move the tapes with one hand while guiding them into the slots of the EST with the other hand. Continue spooling until the tapes show a few inches out from the ends of the EST’s as shown in photo 26.

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Step 15 – Attach a bullet onto the end of each copper tape. Add a drop of super glue to ensure the bullets do not come off the tapes. Squeeze the bullets tightly with pliers. Once the super glue dries, use the spocket to bring the tapes back into the EST to where the bullets come to a stop inside the EST.

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Step 16 – Test the EHU to make sure it works. The first video (below) is with the EHU upside down. The second video is the EHU right side up as it would be on the tower.More

Video #1

Video #2

This completes the rebuild. On Saturday, January 27, 2018, I reinstalled the EHU back onto the antenna and it worked fine.

73, Don AA5AU