[Elecraft] [K2] Inductivity of Toroids

[Brian Alsop]

Don,

Interesting that one never knows just how the quoted inductance is 
determined.

Do you have any idea just how the Elecraft quoted inductances are 
determined?

If measured, what frequency and test jig.
If based upon calculations, how much as built variation will there be.

Have had the same problems as Daniel.  The objective of my measurements 
is usually to determine the the toroid is the right one.  Color aside, 
there are so many bad/counterfeit parts out there, I want to detect such 
a beastie before installation.

73 de Brian/K3KO


On 1/1/2013 14:37, Don Wilhelm wrote:
> Daniel,
>
> The inductance of the RF Choke toroids measured at DC or low frequencies
> may not agree with the published inductane which is measured at a higher
> frequency.  Those RF Chokes are not critical, they just need to block
> the RF flow and the bypass capacitor takes care of the rest.
>
> The inductors that are critical are those in the Low Pass Filter. In any
> case, wind them as instructed in the manual and spread the turns over
> 85% of the core and they will work.  There are over 7000 K2s out there
> working fine with the toroids wound as instructed in the manual.
>
> 73,
> Don W3FPR
>
> On 1/1/2013 9:14 AM, Daniel Heise wrote:
>> Dear K2-Experts,
>>
>> I´m just assembling my K2, and it´s true: It really is addictive :)
>> After winding my first toroid inductors, I measured their inductivity
>> with an atlas LCR40 component analyser before I soldered them into the
>> RF board.
>> Though I closely adhered to the manual, the measured inductivities are
>> almost twice as high than the values stated in the manual (on the
>> parts list in appendix A).
>>
>> It was good to read on the elecraft homepage, that the inductivities
>> are not too critical for the entire function of the transceiver. But
>> I´m still wondering if anyone else measured the inductivities of the
>> toroid inductors and made similar experiences...
>>
>> 73, Daniel
>> DL6MCL
>> Goettingen, Germany
>
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