Re: any tips for debugging RFI issue? #ubitx-help

Mike KK7ER


Thanks for all the suggestions!  Regarding your points:
  • I do not have a star washer at the coax connector on the uBITX.  Nor do I have star washers under the mounting posts.  I'll give that a try.
  • The matching box is this one:
  • There was no manual but the seller pointed me to this page:  I had 100ft of wire and wanted to use 40m-10m so I cut it in two to make a 39ft piece and a 61ft piece.  Both those lengths fit the 40m-10m range in the colorful table on that web page.  I started with the 39ft one at first then switched to the 61ft piece.
  • The SWR is 1:1 at the desired frequency of 14.074 MHz.
  • FYI, I'm in a townhouse.  The 25ft coax goes through the wall up into the attic and through the soffit to the matching box hidden under the eave (about 20 feet above ground).  The antenna wire runs under the eave south for about 13 feet, makes a 100 degree turn West and slopes downward with the end of the wire being about 10 feet above the ground.
  • I had a ferrite on the power cable (you can almost see it in the photo) and tried building and inserting an air choke where the cable came out of the wall.  But if the coax is radiating that badly then the part beyond the air choke inside the wall 2 feet from the uBITX likely renders that moot.
  • Would installing the air choke at the matching box be an option?  It would mean just a few inches of counterpoise/coax before the air choke.
  • Would installing the 31 feet of extra wire on the counterpoise side help?
Thanks again!

73 Mike KK7ER

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