A New Choke Book - Some Questions

[VK1OO, Mike Walkington]

Hi Jim,

Thanks for the New Choke Cookbook.
Looking at your data, it seems to me that I could build a two core choke
for the higher frequency bands and "spread" the overall choking
impedance out by using different turns on each core, ie 11 turns on a
2.4" and 12 turns on a 2.4" . I believe there are no issues doing so,
but would appreciate your confirmation.

Also, do you have any guidance on the spacing required when packaging a
two core choke, ie if the two cores were in a box, what vertical spacing
is required between them?

Cheers
Mike, VK1OO

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[Jim Brown-10]

On 3/14/2019 2:47 PM, Mike Walkington wrote:
> Hi Jim,
>
> Thanks for the New Choke Cookbook.
> Looking at your data, it seems to me that I could build a two core
> choke for the higher frequency bands and "spread" the overall choking
> impedance out by using different turns on each core, ie 11 turns on a
> 2.4" and 12 turns on a 2.4" . I believe there are no issues doing so,
> but would appreciate your confirmation.

Right, and I say that in the text.

>
> Also, do you have any guidance on the spacing required when packaging
> a two core choke, ie if the two cores were in a box, what vertical
> spacing is required between them?

I have done no research on that.

If putting chokes in an enclosure it must be vented to prevent
destructive failure due to overheating. That is also addressed in the
text, and with a photo.

73, Jim K9YC

>
> Cheers
> Mike, VK1OO
>

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[k6dgw]

Disclosure:  There is no theory behind what follows.  I just tried it
and it worked.

I used to host the local rural wireless ISP's RAP at the top of my tower
in return for Internet access to their high speed backbone. During an
equipment upgrade, they brought in a cheap Chinese SMPS which put
broadband 20 over S9 noise on 160, 80, 60, and 40.  I consulted Jim's
choke dissertation and bifilar wound two 2 1/4" toroids ['43 material, I
think], one with about 10 turns, and one with about 18, and connected
them in series.  I zip tied them, one on top of the other separated only
by the windings of #12 vinyl insulated wire, and routed both sides of
the 48 VDC power thru the bifilar windings.  Noise disappeared.  YMMV,
but it isn't hard or costly so if it doesn't work, you're not out much.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 3/15/2019 1:08 AM, Jim Brown wrote:

> On 3/14/2019 2:47 PM, Mike Walkington wrote:
>> Hi Jim,
>>
>> Thanks for the New Choke Cookbook.
>> Looking at your data, it seems to me that I could build a two core
>> choke for the higher frequency bands and "spread" the overall choking
>> impedance out by using different turns on each core, ie 11 turns on a
>> 2.4" and 12 turns on a 2.4" . I believe there are no issues doing so,
>> but would appreciate your confirmation.
>
> Right, and I say that in the text.
>
>>
>> Also, do you have any guidance on the spacing required when packaging
>> a two core choke, ie if the two cores were in a box, what vertical
>> spacing is required between them?
>
> I have done no research on that.
>
> If putting chokes in an enclosure it must be vented to prevent
> destructive failure due to overheating. That is also addressed in the
> text, and with a photo.
>
> 73, Jim K9YC
>

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[VK1OO, Mike Walkington]

Hi Jim,

Thanks. I don't know how I missed the section "Chokes in Series"!

I really appreciate the extensive work you did to build and measure all the
chokes. You are making a difference to small suburban stations like mine
that live in a sea of noise.

Cheers
Mike, VK1OO



-----


Cheers
Mike
VK1OO (ex AC7MZ, VK1KCK)
K2: 2599
--
Sent from: http://elecraft.365791.n2.nabble.com/
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