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I have 70 feet of bare wire running from a tree up about 14 feet, sloping down to my house and then running at a 45 angle under my soffet and then down to where I'm hooking up to a 4:1 unum and grounded counter poise about 25 feet long. Total bare wire entering the unum is 84 feet. From there running into my basement via sma coax. Am I doing anything wrong here, I'm using ceramic insulators meant for electric fencing as to not ground out the bare wire. Any suggestions, using this only for shortwave reception right now, may get into ham radio in the near future.

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Sounds fine as a receiving antenna, however, there is one key element missing from your plan: lightning protection.

You need to either disconnect the antenna (somewhere outside your house) whenever bad weather approaches or might occur while you're away, or install a suitable protection device which is grounded outside your house (and properly integrated with your house's existing grounding system).

Otherwise, you're creating a path for lightning strikes to destroy wiring inside your house and start fires. (Even with protection, you should expect electronic equipment damage from the induced voltages; lightning protection at this level is about not also having a house fire.)

Proper lightning protection is a complex topic and I can't advise you about it; for myself I've always addressed this problem by not putting any permanent antennas close enough to the sky to be plausibly hit.

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  • $\begingroup$ I ran a ground wire from the Unum to a metal rod buried outside the house, will this prevent any lightning damage? Also, I have an mla30 active loop on my roof that's not grounded at all. $\endgroup$
    – bolson437
    Commented Feb 1 at 19:59
  • $\begingroup$ Or could I incorporate a lightning arrester to a ground wire, post choke on my sma cable? $\endgroup$
    – bolson437
    Commented Feb 1 at 20:31
  • $\begingroup$ @bolson437 As I already wrote, I'm afraid I can't give you concrete advice about lightning protection design. I just know that it is necessary for an antenna such as yours. $\endgroup$
    – Kevin Reid AG6YO
    Commented Feb 2 at 0:36
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    $\begingroup$ Bare wire of that length is subject to very high DC voltages when it's windy & the air is dry. Use an Ohm meter to make sure you have a 0 or near 0 Ohms between the connection of your 84 feet of wire to the UnUn, and ground! And if you don't have any low resistance connection to ground, put a 1k-2k Ohm resistor between the bare wire and your ground. Those values will barely affect your receive, but you will likely fry your receiver's front-end without that bleed-off protection. $\endgroup$
    – Lou-in-USA
    Commented Feb 8 at 1:36

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