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K2 4 MHz Oscillator Cal

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Mark Yergin

K2 4 MHz Oscillator Cal

I found that when both my external FC probe and the probe provided by the
kit were attached to TP3 the K2 frequency reading was lowered significantly
(~12070 from about 12098) vs when measured separately. C22 could not make
a match. Separately the two measurements were fairly close, and I could
use C22 to make them the same using the hold feature on my external FC to
capture it's reading, and adjusting C22 to match it on the K2 with only the
kit probe attached. Is this OK? The manual talks about having both
connected at the same time, but the interaction of the two was an issue for
me.

Mark W8EWH
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Don Wilhelm

Re: K2 4 MHz Oscillator Cal

Mark,

What kind of probe are you using on your external frequency counter?
You should be using a 10x probe like you would use on an oscilloscope to
keep the loading of the circuit by the probe capacity to a minimum.

73,
Don W3FPR

On 4/21/2019 11:30 AM, Mark Yergin wrote:

> I found that when both my external FC probe and the probe provided by the
> kit were attached to TP3 the K2 frequency reading was lowered significantly
> (~12070 from about 12098) vs when measured separately. C22 could not make
> a match. Separately the two measurements were fairly close, and I could
> use C22 to make them the same using the hold feature on my external FC to
> capture it's reading, and adjusting C22 to match it on the K2 with only the
> kit probe attached. Is this OK? The manual talks about having both
> connected at the same time, but the interaction of the two was an issue for
> me.
>

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Mark Yergin

Re: K2 4 MHz Oscillator Cal

BNC with mini test clips. I can switch in 10x (or 1x) on the FC but that
doesn't make any difference.

FC is a BK Precision 1823A.

Mark

On Sun, Apr 21, 2019 at 11:37 AM Don Wilhelm <[hidden email]> wrote:

> Mark,
>
> What kind of probe are you using on your external frequency counter?
> You should be using a 10x probe like you would use on an oscilloscope to
> keep the loading of the circuit by the probe capacity to a minimum.
>
> 73,
> Don W3FPR
>
> On 4/21/2019 11:30 AM, Mark Yergin wrote:
> > I found that when both my external FC probe and the probe provided by the
> > kit were attached to TP3 the K2 frequency reading was lowered
> significantly
> > (~12070 from about 12098) vs when measured separately. C22 could not
> make
> > a match. Separately the two measurements were fairly close, and I could
> > use C22 to make them the same using the hold feature on my external FC to
> > capture it's reading, and adjusting C22 to match it on the K2 with only
> the
> > kit probe attached. Is this OK? The manual talks about having both
> > connected at the same time, but the interaction of the two was an issue
> for
> > me.
> >
>

Don Wilhelm

Re: K2 4 MHz Oscillator Cal

Mark,

I am not talking about the 10x/1x sensitivity scaling of your frequency
counter itself.
I am referring to the capacitance of the probe itself. You should be
using a 10x 'scope probe which has a low capacity and will not load the
PLL Reference circuit.

73,
Don W3FPR

On 4/21/2019 1:07 PM, Mark Yergin wrote:
> BNC with mini test clips. I can switch in 10x (or 1x) on the FC but
> that doesn't make any difference.
>
> FC is a BK Precision 1823A.
>
>

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Mark Yergin

Re: K2 4 MHz Oscillator Cal

Tried a 10x scope probe and that did the trick. Thank You!.

Mark

On Sun, Apr 21, 2019 at 5:48 PM Don Wilhelm <[hidden email]> wrote:

> Mark,
>
> I am not talking about the 10x/1x sensitivity scaling of your frequency
> counter itself.
> I am referring to the capacitance of the probe itself. You should be
> using a 10x 'scope probe which has a low capacity and will not load the
> PLL Reference circuit.
>
> 73,
> Don W3FPR
>
> On 4/21/2019 1:07 PM, Mark Yergin wrote:
> > BNC with mini test clips. I can switch in 10x (or 1x) on the FC but
> > that doesn't make any difference.
> >
> > FC is a BK Precision 1823A.
> >
> >
>
>