I C 8 P O F
Ultrabeam yagi antenna UB620 3elements
maintenance report

In november 2020 I have had the opportunity to buy a ten years used UB620 yagi antenna.

• I have found many problems that needed to be solved, below I write how to repair them.
  
  
  • VTR\Fiberglass
     Poles had the fiber degraded by sunlight and salty humidity being near the sea
     the black ones are 10 years old.
     The transparent ones are two years old have also a degraded surface; they have been changed by the
      previous owner after a rupture due a strong wind.
          new painting"
    

   

  •   3...-- repainting :   given the impossibility of treating the fiberglass in a safe enviroment, I decided not to polish the tubes .
                Just painted over two times with a green color.
                *** but remember to use handgloves to handle them.***

  •   4 ....-

   

  • Tapes
        -->> ground testing .....
        the red circle indicates a lost screw, read below ...

     

     

   

   

   

      apart from the strong burn of the right driver and the obvious oxidation due to the long use,
       the tapes and the sliding contacts are all ok
  
  

  -->> severe burn	-->> rebuilt point	-->> oxidized&cleaned	...
  ...*	the running tip has been rebuilt.	the SIDOL cleaner removes the oxidation and    burns and cleans very well the tapes.

  
  
  
  
  
  • ...Infiltrazione, water leakage : after many years of use one of the screws holding the director internal motor-plate  
       has unscrewed itslef leding to a little water infiltration that caused some oxidisation
       and on the radiator box one screew lacked at all.
      

    1 link to larger pic ->

    2 loose screw

    3manca vite - lack of screw

  
  
  
  
  • Motor boxes holding screws : All the motor-housing holding screws resulted in a lose situation
      due to bad blocking nuts, therefore I had to change all with new ones.
      the yellow circled screws are the WARRANTY state indicators that most be carefully cut to open the motor-boxes.
       
    
  
  

   

  • Boom to mast plates
     -->>boom to plate oxidation
    the severe oxidation between the aluminium boom and the inox antenna holding plate has been cleaned and NOALOX paste has been put. 
    
  
  
  

   

   

  

   

  • Motors Controller > :
      all the buttons were not centered in the front panel holes anymore so they did block at every pressing
      therefore I had not only to move the internal pcb for a better alignment, but I had also to file some holes
       to let them be centered in them for a better working travel.
    

    ,,,1   ....	-.- ......filing few tenths of millimetre to get centered the buttons
    front panel removing, using a cutter pay attention to not damage the panel.	yellow dots indicate where have been filed few tenths for better buttons moving

    
    
    
  

   

   

  • Multiwire cable    nothing special to mention
    I had just a little fear about a new cable entering into the shack for possible RFI, but untill now more that one year later I have noted no RFI.
  
  
  
  • Impressions between the old and the new yagi antenna :   after 20 and more years of use of the KLM KT34 antenna I must admit that
           this motorized project is very fine and the 180° direction inversion is a must have.
    
  
  
  
  • Automatic BAND_Change : even if I have tested and understood how to use it, at the present time I do not use this feature.
    
  
  

Any improvement or suggestions will be appreciated,
Write to my to my email on ic8pofATyahoodotcom (copy,paste and correct)
.

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dic2020, gen-apr22