[Lowfer] Common Mode Chokes (was Active Whips)

[Pat Bunn]

I followed Jacks advise and have a choke about ten feet from the base of the antenna with two driven ground rods.(l also have 2 rods at the antenna base. The choke ten feet from the antenna is grounded on the antenna side (I used a TV type ground to ground the shield) 

I have another choke at the receiver end with again a good driven ground on the antenna side of the choke.

My results have been better than I could have hoped for. Before, I tried to listen to lf with a full size 80 meter dipole. The man-made noise was so bad it was impossible to hear anything. With the probe located well away from the house and chokes in all lines coming into the shack I rarely have any man made noise.

Pat
N4LTA

"Douglas D. Williams" <kb4oer at gmail.com> wrote:

>I count twenty turns. I did another one with just two cores glued together
>and was about to get about thirty turns through that one. I have them
>connected in series on the coax between the indoor dc power coupler and the
>antenna, so they have dc voltage going through them. Thought about putting
>another one at the base of the antenna, but that would just introduce
>another point where moisture might get into the coax...
>
>I also used those same toroids on all my DC power leads inside the shack,
>wrapping as many turns as I could through them each time. I have
>some toroids left over, so I may do all my USB and CAT5 cables next, lol.
>
>73, Doug KB4OER
>
>On Thu, Jan 24, 2013 at 7:00 PM, Dexter McIntyre W4DEX
><dexter.mc at gmail.com>wrote:
>
>> Thanks for the info Doug.  The coax you used looks a bit larger in
>> diameter than the RG-174 I'm familiar with.  How many turns did you get
>> through the 23 mm ID of the cores?  Looks like maybe 30?
>>
>> Dex
>>
>>
>> Douglas D. Williams wrote:
>>
>>> Regarding the Clifton Labs common mode choke plans, once I told Jack at
>>> Clifton Labs that I was mainly interested in 8 kHz to 500 kHz reception
>>> and
>>> was planning on building one of his common mode chokes he told me, and I
>>> paraphrase, to glue five 40T1417-10H (Digi-Key part # 240-2537-ND)
>>> together
>>> and to wrap as many turns of RG-174 through them as I could fit. This I
>>> did.
>>>
>>> https://dl.dropbox.com/u/**33457409/common%20mode%**20choke.jpg<https://dl.dropbox.com/u/33457409/common%20mode%20choke.jpg>
>>>
>>> 73, Doug KB4OER
>>>
>>>
>>>
>>
>> ______________________________**______________________________**__
>> Lowfer mailing list
>> Home: http://mailman.qth.net/**mailman/listinfo/lowfer<http://mailman.qth.net/mailman/listinfo/lowfer>
>> Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm>
>> Post: mailto:Lowfer at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>______________________________________________________________
>Lowfer mailing list
>Home: http://mailman.qth.net/mailman/listinfo/lowfer
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:Lowfer at mailman.qth.net
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html