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One of the tapes in the Driven element Element Housing Unit (DVR EHU) had jumped the sprocket which prompted the antenna to fail when it was 2 elements. The EHU also had a good sized hole in the top of the housing, which presumably was created by a woodpecker or large bird.
On first inspection, the EHU looked OK other than minor bends in the top copper tape and some pieces of grass. There was no water or moisture inside the EHU when it was opened.
I removed the tape spools and tested the EHU. At that time I noticed corrosion around the top of the motor. The motor tested fine as you can see in the video below.
Video 1 – Testing the motor in the DRV EHU
After testing the EHU, the base plate was removed. Other than the hole in the top of the EHU, the housing and balun looked good. I blew out all the grass and other debris with canned air.
A closer inspection of the motor showed severe corrosion on the outside. I turned the motor shaft by hand and compared it with two other motors and it did not feel smooth. I decided at that point not to reuse this motor.
The motor was replaced with a spare. The sprocket connected to the spare motor was held in place by a pin instead of the newer-style method of a screw and nut. This caused the sprocket to be loose and wobble when turned. The plan was to put the original sprocket with the screw and nut onto the spare motor. I first had to remove the pin holding the sprocket to the spare motor shaft. I tried tapping the pin out but it wouldn’t come out so it was drilled out.
Once the sprocket was installed on the replacement motor, the next step was to install the motor onto the base plate and solder the wires into the connector board.
Sticky tape was used to secure the wires to the base plate.
The base plate assembly is now complete.
Before re-installing the base plate into the shell, the hole in the top of the shell needed to be repaired. In order to determine the best way to repair the hole, I had tested various methods on a damaged shell I had kept (the shell damaged in Hurricane Isaac in 2012 that prompted me to convert this antenna to 2 elements in the first place).More
On the hurricane-damaged shell, I drill four holes about the size of the hole in the DRV EHU shell. On the first hole, I super-glued a penny over the hole and let is sit overnight. I then used epoxy to cover the penny and let it sit overnight. This didn’t work very well, The epoxy didn’t set and it never hardened although i did like the way the glued penny covered the hole. I then glued pennies over the other 3 holes. On the second hole, I covered the penny with JB Weld. I was familiar with JB Weld because I had used it several times in the past. I used it once to repair the block of an outboard motor and about seven years ago, I used it to repair the cast aluminum base of my mailbox. This showed me it would hold up to ultra violet light. I liked the result of the JB Weld test. The reason I used a penny was so that if another bird decided to peck into the top of the EHU, the penny would hopefully act as a second line of defense. I guess time will tell.
A penny and JB Weld were used to repair the hole in the top of the EHU. I first sanded the top of the EHU to allow the JB Weld to adhere to the surface.
A penny was then super-glued over the hole and let sit for several hours.
After the super glue set, JB Weld was then used to cover the penny and allowed to set overnight.
After the JB Weld set for 24 hours, JB Weld was also used on the inside. I didn’t want the surface of the penny to be exposed so it wouldn’t corrode.
After the JB Weld inside the EHU set for 24 hours, I tested to make sure there was enough clearance for the motor. I put a small dab of Elmer’s glue on top of the JB Weld then set the base plate assembly into EHU temporarily to see if there was any Elmer’s glue on the motor. There wasn’t. The base plate assembly sat correctly in the EHU. The hole in the EHU was now repaired.