[Boatanchors] Xmtr impedance

[Don Buska]

Hi Frank,

Way back in the 70's I worked for Milwaukee Resistor Company which made 
only wirewound resistors.  Yes they did make non-inductive wire wounds. 
  Basically it was two winding wound over each other in opposite 
direction, i.e. one was C.W. and the other C.C.W.  I'm not sure how high 
in frequency they could be used. As I'm sure other factors due to 
natural imperfection would have varying impedances enter the picture as 
we move up in frequency, albeit this is true with an dummy load.  They 
all have upper frequency limits!

I had six large 250 watt (300 ohms each) non-inductives wound for me 
when I worked there.  Unfortunately I never got around to paralleling 
them together and trying them out on HF.  Ended up giving them away back 
in the 80's and they probably got used or thrown out along the way.

So yes, wire-wounds can be made non-inductive.

73

Don N9OO

fkamp at comcast.net wrote:
> StephenTetorka at cs.com wrote:
> 
>> I like Ron's idea about using the non-inductive resistances.
>>
>> Simple and data-worthy.
>>
>> I have an old CQ or QST from the 30's having an article on making a 
>> non-inductive dummy load using resistance wire...I just happen to have 
>> a spool of nichrome at 0.406 ohms per foot.
>>
>> Worth the try guys?
>>
>> Any advice?
>>
> 
> Lately I have become a little more careful about giving advice.  
> Sometimes it does more to confuse than help.  Other times, what I 
> consider good advice is not entirely without flaws.
> 
> A non-inductive dummy load using resistance WIRE!?
> 
> I was under the impression that all wire had a certain amount of 
> inductance.  Isnt that why we use it build coils?  Isnt that why power 
> resistors using resistance wire are not suitable for building 
> non-inductive dummy loads?  Or is there some construction method that 
> eliminates the inductance?  If so, does it work over a range of 
> frequencies?  How large a range?
> 
> If it were me, I would check to make sure the article did not come out 
> of an April edition.
> 
> Regards,
> Frank Kamp
> K5DKZ
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