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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