Agreed Steve, talk to Butch M. Roger. Tell him your a ham and I sent you
from ATC. He will know what you mean and this is what he does for a
living. He may be able to give you some free advise.
AMCoordination@aol and I will leave the .com off for the bots.Butch is a
good guy.
D.Calder
73 Dave n4zkf
On 8/31/13 4:59 PM, "Steve Maki" <lists@oakcom.org> wrote:
>You tune for minimum current in the skirt, at least the ones I've had my
>hands on. The tuner and RF sampler is connected between the skirt and
>ground. I've assumed that the skirt and tower become *one* due to their
>close proximity.
>
>The tuning for minimum is quite sharp, which is fine for an AM station
>that never moves frequency. Retuning is required when tower
>appurtenances are modified substantially.
>
>It seems to me that in your case you would tune for minimum on your
>favorite frequency and hope that there is enough detuning effect over
>your desired bandwidth.
>
>-Steve K8LX
>
>On 8/31/2013 3:38 PM, Roger Parsons wrote:
>
>> Sorry Dave, I guess I didn't make myself clear.
>>
>> The tower has never had a detuning skirft on it, but I am considering
>> putting one on. I am aware that detuning skirts are most often used
>> to prevent some other structure re-radiating ones wanted signal as in
>> the case of your towers and AM broadcast stations.
>>
>> What I want to do is slightly different. My antenna is not the actual
>> tower, but a wire some six feet away from the tower and parallel with
>> it. It obviously couples very strongly into the tower, and it seems
>> to me that the tower is just about the right size to be 3/4 wave
>> resonant on 160m. That is a pretty bad length as (1) it will accept a
>> lot of power and (2) its major radiation lobe will be upwards - not
>> what is wanted at all.
>>
>> I believe that a skirt with a series reactance can change the
>> resonant point of the tower. What I am very unclear about is how I
>> can adjust it - I believe that normally the skirt is tuned for
>> minimum current in the tower or maximum current in the skirt. I don't
>> think that either of those conditions will necessary be right in my
>> case!
>>
>> 73 Roger VE3ZI
>
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