If one has heating issues to that magnitude, they have other more critical issues which should be addressed.
Bob, K4TAX Sent from my iPhone > On Feb 9, 2016, at 9:24 AM, Dave Cole <[email protected]> wrote: > > Hello Bob, > > The coax could be exposed to heat when in service as a balun, so I > would respectfully disagree with you on this one point. > > If you exceed the bending radius of your coax, you stand a higher > percentage chance of causing a shield to center connector short, (due > to center conductor migration), than if you don't exceed the bend > radius. When running high power, you also stand a better chance of > heating up your core material, (and hence your coax), which makes it > easier for the center conductor to migrate, and if you have exceeded > the bend radius-- well-- we're pretty sure where it will migrate > too... > > One has to pick one's fights so to speak, and I would not pick bending > radius as one of my fights... > > If you lose, it is never good when the center conductor shorts to the > shield at Kilowatt power levels. Use loops large enough to stay within > the bending radius of your coax. Now if this is QRP, you could > probably get away with it. > > -- > 73's, and thanks, > Dave > > For software/hardware reviews see: > http://www.nk7z.net > > For MixW support see: > https://groups.yahoo.com/neo/groups/mixw/info > > For SSTV help see: > http://groups.yahoo.com/neo/groups/MM-SSTV/info > > > >> On Tue, 2016-02-09 at 09:01 -0600, Bob McGraw K4TAX 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 <[email protected]> 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 >>>> [email protected] <javascript:_e(%7B%7D,'cvml','[email protected]');> >>>> >>>> >>>> On Feb 8, 2016, at 18:01, Guy Olinger K2AV <[email protected] >>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> 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. >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
