Since my current antenna situation is a far cry from ideal (and far from what
it used to be), I run a common mode choke at the antenna feed point and one at
the radio end of the coax for exactly that reason.
J.P. W2XX/7
> On Jan 26, 2023, at 6:29 PM, David Gilbert <ab7echo@gmail.com> wrote:
>
>
> I'm not trying to promote choke overkill, but look at it this way. If it is a
> truly high impedance CMC at the antenna, the shield of the remaining coax run
> to the shack is essentially a receiving antenna with an open end at the
> antenna. If the antenna is a vertical with radials, the coax becomes just
> another radial. I don't understand why there wouldn't be additional currents
> on the coax shield in those cases ... over and above the differential
> currents the coax is carrying. If so, depending upon the circumstances, it
> seems you might want a CMC at the shack end of the coax as well.
>
> I don't use one there myself, but I've often wondered whether or not I should.
>
> 73,
> Dave AB7E
>
>
>
>> On 1/26/2023 5:39 PM, john@kk9a.com wrote:
>> The only location where I use a choke is at the antenna feed point.
>>
>> John KK9A
>>
>>
>> Art Greenberg WA2LLN wrote:
>>
>> The questions:
>>
>> I realize that the bonding and lightning ground system isn't an RF
>> ground, but I wonder if it influences the location(s) of common mode chokes?
>>
>> I -think- a CM choke is appropriate at the antenna feedpoint, despite
>> the bonding setup. Is that true?
>>
>> Is an additional CM choke appropriate near the bottom of the tower? On
>> which side of the bonding at the bottom of the tower?
>>
>> Is an additional CM choke appropriate before the lightning arrestor? Or
>> between the lightning arrestor and the equipment?
>>
>> TNX
>>
>
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