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Magnetic Shielding Kit Now Available for K2's VCO Inductor

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wayne burdick

Magnetic Shielding Kit Now Available for K2's VCO Inductor

Administrator

The K2’s VCO (voltage-controlled oscillator) may be susceptible to
low-frequency modulation by very large power transformers, such as
those in linear amp power supplies and antenna rotator controllers.
Such modulation can usually be eliminated by simply moving the
equipment away from the transceiver. In difficult cases, magnetic
shielding can be used, and we've created a modification kit for this
purpose (Order #K2VCOSHLDKT).

The mod kit provides a smaller replacement core for transformer T5, a
high-permeability ferrite sleeve, and associated hardware. The ferrite
sleeve is installed over T5, greatly reducing the effect of nearby
strong magnetic fields. In addition, slug-tuned inductor L30 must be
electrically disabled since it, too, is affected by magnetic fields.
With L30 out of the circuit, the VCO inductance can still be adjusted,
if necessary, by slightly squeezing or spreading the turns of T5.

The kit is priced at $10. For more information, see our parts order
page:

http://www.elecraft.com/order_form_parts.htm#K2%20Parts

73,
Wayne, N6KR

---

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Vic K2VCO

Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

wayne burdick wrote:

> (Order #K2VCOSHLDKT).

I am deeply honored to have an Elecraft part number named after me.

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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wayne burdick

Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

Administrator

It was the least we could do, Vic ;) Thanks for your help testing
mods like this one.

Wayne
N6KR

On Oct 6, 2005, at 3:31 PM, Vic K2VCO wrote:

> wayne burdick wrote:
>
>> (Order #K2VCOSHLDKT).
>
> I am deeply honored to have an Elecraft part number named after me.

---

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Able2fly

Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

In reply to this post by wayne burdick

In a message dated 10/6/2005 6:28:59 P.M. Eastern Daylight Time,
[hidden email] writes:

The K2’s VCO (voltage-controlled oscillator) may be susceptible to
low-frequency modulation by very large power transformers
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Will future K2 kits incorporate the mag shielding mod?

Bill K3UJ

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JEAN-FRANCOIS MENARD-3

Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

In reply to this post by wayne burdick

1- Will it be more difficult to tune T5 instead of asjusting L30 ?
2- Will it be standard in K2 kit now or it is just optional ?
3- Will we loose precision on the VCO stability, or any other manner
regarding performance when applying this mod ?

I'm planning to buy and build another K2... very soon... ;-)

73

Le 05-10-06 à 18:31, wayne burdick a écrit :

> The K2’s VCO (voltage-controlled oscillator) may be susceptible to
> low-frequency modulation by very large power transformers, such as
> those in linear amp power supplies and antenna rotator controllers.
> Such modulation can usually be eliminated by simply moving the
> equipment away from the transceiver. In difficult cases, magnetic
> shielding can be used, and we've created a modification kit for
> this purpose (Order #K2VCOSHLDKT).
>
> The mod kit provides a smaller replacement core for transformer T5,
> a high-permeability ferrite sleeve, and associated hardware. The
> ferrite sleeve is installed over T5, greatly reducing the effect of
> nearby strong magnetic fields. In addition, slug-tuned inductor L30
> must be electrically disabled since it, too, is affected by
> magnetic fields. With L30 out of the circuit, the VCO inductance
> can still be adjusted, if necessary, by slightly squeezing or
> spreading the turns of T5.
>
> The kit is priced at $10. For more information, see our parts order
> page:
>
> http://www.elecraft.com/order_form_parts.htm#K2%20Parts
>
> 73,
> Wayne, N6KR
>
>
> ---
>
> http://www.elecraft.com
>
> _______________________________________________
> Elecraft mailing list
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> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

=============================================
/¯\/¯\/¯\/¯\/¯\/¯\ JEAN-FRANCOIS MENARD
V A 2 V Y Z [hidden email]
\_/\_/\_/\_/\_/\_/

Elecraft K2 #4130
Elecraft KX1 #999

http://homepage.mac.com/jfmenard
=============================================

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wayne burdick

Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

Administrator

> 1- Will it be more difficult to tune T5 instead of asjusting L30 ?

Yes, a little. But this method is used for aligning the K1's VFO, so it
can't be that hard :)

> 2- Will it be standard in K2 kit now or it is just optional?

It will remain optional since it's easier to build the kit the original
way. This modification is only intended for those who have a
significant modulation problem, and cannot solve it by moving things
around. Fortunately, few K2 owners fall into this category.

> 3- Will we loose precision on the VCO stability, or any other manner
> regarding performance when applying this mod ?

No. VCO performance is identical in all other ways.

73,
Wayne

---

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JEAN-FRANCOIS MENARD-3

Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

Thanks, because I experiment this phenomenon with my Ameritron
AL-811H that is near my K2... maybe to near (8 to 9 inches), but I
can't move it farther.. :-(

73

Le 05-10-06 à 20:06, wayne burdick a écrit :

>
>
>> 1- Will it be more difficult to tune T5 instead of asjusting L30 ?
>>
>
> Yes, a little. But this method is used for aligning the K1's VFO,
> so it can't be that hard :)
>
>
>
>> 2- Will it be standard in K2 kit now or it is just optional?
>>
>
> It will remain optional since it's easier to build the kit the
> original way. This modification is only intended for those who have
> a significant modulation problem, and cannot solve it by moving
> things around. Fortunately, few K2 owners fall into this category.
>
>
>
>> 3- Will we loose precision on the VCO stability, or any other
>> manner regarding performance when applying this mod ?
>>
>
> No. VCO performance is identical in all other ways.
>
> 73,
> Wayne
>
>
> ---
>
> http://www.elecraft.com
>
>

Vic K2VCO

Re: Re: Magnetic Shielding Kit Now Available for K2's VCO Inductor

JEAN-FRANCOIS MENARD wrote:

> Thanks, because I experiment this phenomenon with my Ameritron AL-811H
> that is near my K2... maybe to near (8 to 9 inches), but I can't move
> it farther.. :-(

I did a little test in which I held my soldering gun which contains a
transformer about 30 cm above the unmodified K2, at which point I heard
a distinct modulation. After the modification it could be 5 cm away
before I heard it. It definitely made a big difference.

Of course it would be best to have the K2 on the side of the AL80 that
is away from the transformer and fan motor.

Also, I did not find it hard to adjust the voltage by squeezing the
turns on the core.

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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