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Author Topic: To Balun or Not To Balun...  (Read 947 times)
NG1J
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Posts: 26




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« on: August 04, 2002, 11:45:54 AM »

After 9 years of being out of the loop (no pun intended), I'm setting my station back up again.  I'm hoping to avoid/eliminate as much RFI/TVI as possible.  So, in addtion to a good ground and low pass filter, I'm considering winding a few turns of coax both at the antenna (I'll be putting up a dipole...MAYBE a vertical) and at the antenna tuner.

So here's my 2 part question: a)how many turns and what diameter? (I seem to remember 6 turns @ 8" diameter) and b)is doubling up on the baluns overkill?
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WB2WIK
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Posts: 20611




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« Reply #1 on: August 05, 2002, 08:48:16 AM »

Hmmm.

Any "coaxial RF choke" type balun has a limited frequency range of effectiveness, so one that is ideally suited for 20m will not be ideally suited for 40m.  You didn't say what band(s) your dipole or vertical will cover.

An actual balun, as opposed to a choke, is likely a better idea for the dipole, since you're using unbalanced line to feed a balanced antenna.  Wideband ferrite baluns don't weigh much (often far less than 6 turns of RG213/U wound into an 8" diameter coil, which is 13 feet of coax and will weigh 1-1/2 lbs if you don't use any coil form).  A good choice is RadioWorks model B1-2K.  The vertical shouldn't need a balun, but a model T-4 ferrite isolator isn't a bad idea.

Remember the vast majority of RFI is caused by primary radiation (from the antenna itself), so all the isolators and baluns in the world won't stop that; there's no substitute for "distance," or having antennas located far from equipment that might be interfered with!

WB2WIK/6



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N6AJR
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Posts: 9910




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« Reply #2 on: May 21, 2003, 08:10:20 PM »

I run a hustler 5 band vert ($149 at HRO and I love it  ) Ground mounted with no radials ( tried them and no difference so I took them up) and I use a 6 coil 6 " roll of coax at the antenna (poor mans balun)  and I get no rf in the shack.  

I run it through a tuner to  a switch to 2 rigs. I have made over 2000 contacts on this and am very happy with it.  I only ran the coil at the antenna because I ran out of coax and just ran straight into the tuner.  Works great for me.  hope this helps

 Tom N6AJR
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