[Elecraft] Balun Questions

[Robert Nobis]

Hi Bob McGraw,

I agree, except on one point: I’s say 90%, rather than 75%, of the stuff we use and methods employed would put most of the station stuff in the trash.

73,


Bob Nobis - N7RJN
n7rjn at nobis.net


> On Feb 9, 2016, at 08:01, Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> 
> I'm one of the other Bob's or Robert's........
> 
> Since the assembly of coax wound around a toroid doughnut style bobbin is typically not exposed to vibration, such as might exist in an airplane, boat or space vehicle, the use of a solid conductor coax such as RG-303 would not seem to be of concern.  The more important point and my experience and as related by others, the use of coax which has foam dielectric in a tight radius bend has been proven or shown to be problematic.    As to if the manufactures bending radius dimension is being violated, I find to be of little concern.
> 
> After all, as a rule, hams are noted for pushing things to the limit and then some and getting buy with it.  If hams choose to "stick to the rules 100% in all aspects of their stations"............I'd say 75% of the stuff we use and methods employed would put most of the station stuff in the trash.
> 
> 73
> Bob, K4TAX
> 
> 
> 
> 
> 
> On 2/9/2016 8:45 AM, Guy Olinger K2AV wrote:
>> Hi Bob, et al,
>> 
>> Thank you all for your careful attention.
>> 
>> I read it wrong, as several have pointed out overnight. I transposed that
>> to a percentage in my memory after reading it. One of the reasons for
>> referring people to the original material in these cases. Someone will get
>> it right.
>> 
>> That makes it two and a half hairs :>)  Doesn't appear to change the
>> argument. To me anyway the method is still a crude measurement instead of
>> watching a wide frequency scan while bending the cable along with other
>> performance specific measurements.
>> 
>> I still would not use the solid center conductor versions (RG142/303) on a
>> winding.
>> 
>> 73, Guy K2AV
>> 
>> On Tuesday, February 9, 2016, Robert Nobis <n7rjn at nobis.net> wrote:
>> 
>>> Hi Guy,
>>> 
>>> I am not sure how you arrived at the “2/1000 of an inch” figure from the
>>> ANSI spec? The spec actually says “A change in ovality from a given
>>> sample’s initial measured value of 0.010 inches or more (> 0.010)
>>> represents the point of non-acceptable bending performance.”
>>> 
>>> 
>>> 73,
>>> 
>>> 
>>> Bob Nobis - N7RJN
>>> n7rjn at nobis.net <javascript:_e(%7B%7D,'cvml','n7rjn at nobis.net');>
>>> 
>>> 
>>> On Feb 8, 2016, at 18:01, Guy Olinger K2AV <k2av.guy at gmail.com
>>> <javascript:_e(%7B%7D,'cvml','k2av.guy at gmail.com');>> wrote:
>>> 
>>> 
>>> I also suggest that everyone carefully study the ANSI standard until it is
>>> clear what they are doing mechanically and see what they are actually
>>> measuring:
>>> 
>>> http://www.scte.org/documents/pdf/standards/ANSI_SCTE%2039%202007.pdf
>>> 
>>> The method of measuring is in section 4. They are looking for a limit of
>>> 1% surface deformity when bending.
>>> 
>>> In the case of RG400 with .195 inch OD, that would be 2/1000 of an inch
>>> (yes, that's three zeros, two one thousandths of an inch) bending deformity
>>> at the surface of the teflon jacket, or half the thickness of an average
>>> human hair.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
> 
> 
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