On 10/5/2010 8:10 PM, Mark Robinson wrote:
> If he hung some capacitance hats off the top of the tower, would that work.
Replace those conductive guy lines with Phillystran?
73
Roger (K8RI)
> Maybe something to try.
>
>
> Mark N1UK
>
>
> ----- Original Message -----
> From: "David Gilbert"<xdavid@cis-broadband.com>
> To:<towertalk@contesting.com>
> Sent: Tuesday, 05 October, 2010 3:59 PM
> Subject: Re: [TowerTalk] Tower Detuning
>
>
>>
>> Well, as Jim pointed out (and as I should have) the operating frequency
>> was much higher (12 to 15 times higher), and we used three clamp-ons
>> instead of one. To a first order approximation (I didn't look at the
>> material curves)that's 40 times the choking action of the single
>> identical clamp at 1.8 MHz. We would have used more clamp-ons except
>> that it was already getting kind of expensive and it made sense to see
>> if there was any improvement at all before spending money on more of
>> them. As it turned out, the three clamp-ons for each guy worked well
>> enough that K9RX was satisfied with that.
>>
>> 73,
>> Dave AB7E
>>
>>
>>
>>
>>
>> On 10/5/2010 11:33 AM, Michael Baker wrote:
>>> OK, well that raises another question.
>>> If a clamp on bead works with a single cable and a single turn, why
>>> doesn't
>>> it work with a Tower? Granted, on zig zag reinforcing on the tower, they
>>> would also have to get a bead to break up the path but why not work? If I
>>> can clamp on one each to each leg of an overhead power source to keep RF
>>> off
>>> the service entrance, why not a tower leg?
>>> It is still a single turn?
>>>
>>> Section (cut in half with a diamond wheel) Mix 31 toroids and band them
>>> around the leg. If 5 to 7 work as chokes for coax it should work for the
>>> leg.
>>>
>>> What have I missed? (OK< yes, the guys also must be done as well AND
>>> all
>>> cables descending down the tower.
>>>
>>> Just curious.
>>>
>>> Michael Baker K7DD
>>> k7dd@cox.net
>>>
>>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of David Gilbert
>>> Sent: Tuesday, October 05, 2010 10:11 AM
>>> To: towertalk@contesting.com
>>> Subject: Re: [TowerTalk] Tower Detuning
>>>
>>>
>>> I agree ... one turn through a core is insufficient on 160m.
>>>
>>> Using clamp-ons can be useful in other semi-similar situations, though.
>>> A couple of years ago afriend of mine, K9RX, was having significant
>>> detuning issues with his 3-stack of KT34XA's. He could see the effect
>>> on SWR (and presumably pattern) on either 15m or 10m (I don't remember
>>> which band .. maybe both) as he rotated the stack. He was convinced he
>>> was getting interaction with the top sections of each guy even though he
>>> had them split with insulators per the usual recommended lengths. We
>>> put three Mix-31 clamp-ons from DX Engineering on the top section of the
>>> guys out as far as I could reach from the tower at each level and the
>>> situation dramatically improved.
>>>
>>> 73,
>>> Dave AB7E
>>>
>>>
>>>
>>>
>>> On 10/5/2010 9:28 AM, Jim Brown wrote:
>>>> On 10/4/2010 3:00 PM, Michael Baker wrote:
>>>>> How about using the Giant Clamp on Beads made my Fair-Rite?
>>>>> Clamp one or more on each leg and the descending cables.
>>>> Sorry, that will NOT work -- the impedance of a single turn through
>>>> these parts are FAR too small to have any effect on 160M.
>>>>
>>>> 73, Jim Brown K9YC
>>>> _________________
>>> _______________________________________________
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