The material in the ARRL Handbook is woefully out of date and quite inadequate.
See http://audiosystemsgroup.com/RFI-Ham.pdf for much more effective choke
designs, with measured data to support them.
73,
Jim Brown K9YC
>from the 2008 handbook
>Table 21.4
>Effective Choke (Current Baluns)
>Wind the indicated length of coaxial feed line into a coil (like a coil of
>rope)
>and secure with electrical tape. The balun is most effective when the coil is
>near the antenna. Lengths are not critical.
>Single Band (Very Effective)
>Freq RG-213,RG-8 RG-58
>3.5 22 ft, 8 turns 20 ft, 6-8 turns
>7 22 ft, 10 turns 15 ft, 6 turns
>10 12 ft, 10 turns 10 ft, 7 turns
>14 10 ft, 4 turns 8 ft, 8 turns
>21 8 ft, 6-8 turns 6 ft, 8 turns
>28 6 ft, 6-8 turns 4 ft, 6-8 turns
>Multiple Band
>Freq RG-8, 58, 59, 8X, 213
>3.5-30 10 ft, 7 turns
>3.5-10 18 ft, 9-10 turns
>14-30 8 ft, 6-7 turns
>--
>GB & 73
>KA5OAI
>Sam Morgan
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