[TowerTalk] Fair rite materials for choke baluns

[jimlux]

On 7/6/16 12:31 AM, Steve Hunt wrote:
> Note what I said about duty cycles!
>

I would think that most ham use is a low duty cycle operation (leaving 
you EME and RTTY contesters aside): saturation (and magnetization) is 
purely a peak level thing.  You could saturate a core in a single cycle 
(or dit, or on a short voice peak), and you'd not see any appreciable 
heating.

I wonder if anyone has ever had a core ruined by a lightning impulse?



> Steve G3TXQ
>
>
> On 06/07/2016 00:00, Richard (Rick) Karlquist wrote:
>> On 7/5/2016 11:00 AM, Steve Hunt wrote:
>>> Do the maths on saturation - you'll find that core overheating occurs
>>> well before saturation for the duty-cycles typical of Ham operation.
>>>
>>> To quote Amidon: "Overheating of the core will usually take place long
>>> before saturation in most applications above 100kHz."
>>>
>>> Steve G3TXQ
>>
>> This generalization is valid for cores with an air gap and
>> powdered iron cores (which essentially have a built in air gap).
>> It most definitely doesn't apply to closed gap ferrites,
>> such as toroids.  One dit can not only saturate them, but
>> actually magnetize them.  I have actually done this, accidentally,
>> when I tried to use a current transformer and the secondary
>> was unloaded.  It was something of a corner case since the
>> primary of a current transformer is only 1 "turn".
>>
>> Rick N6RK
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk