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#1
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Gene Fuller wrote:
It appears you missed the primary message of the Corum article. I'm afraid you missed the point. As long as the frequency is kept constant, the VF and Z0 of coil stock will be relatively constant - why wouldn't it be? W8JI missed the 4 MHz delay through that coil by at least a magnitude. It is impossible for that delay to be 3 nS. The measured delay through my 75m bugcatcher coil is 25 nS. -- 73, Cecil http://www.w5dxp.com |
#2
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Cecil Moore wrote:
Gene Fuller wrote: It appears you missed the primary message of the Corum article. I'm afraid you missed the point. As long as the frequency is kept constant, the VF and Z0 of coil stock will be relatively constant - why wouldn't it be? W8JI missed the 4 MHz delay through that coil by at least a magnitude. It is impossible for that delay to be 3 nS. The measured delay through my 75m bugcatcher coil is 25 nS. Yup, I guess I don't understand the "point". You continue to use the equations and charts derived in the Corum article, but you don't agree with his conditions and caveats. There would have been no purpose for his article if your paragraph above was correct. Have you expanded the applicability range for his results? Where can we find your IEEE white paper? So, the "point" is ?????? 73, Gene |
#3
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Gene Fuller wrote:
So, the "point" is ?????? Given a 100 foot long helical transmission line at 4 MHz terminated in its characteristic impedance. The VF is easily measured. This is a slow-wave configuration. Change the length to 50 feet terminated in its characteristic impedance. Why would the characteristic impedance change? Why would the VF change? The coil diameter is 0.5 feet. The coil diameter ratio to wavelength is 0.002. The turns per foot is 48. The turns per wavelength is about 11800. Reading from Fig.1 in the Corum article gives a VF of about 0.02. Why would that change appreciably with frequency? -- 73, Cecil http://www.w5dxp.com |
#4
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On Thu, 29 Nov 2007 17:44:39 -0600, Cecil Moore
wrote: Jim's point is that it can be done! In that particular coil at 4 MHz - no, it cannot be done. On Thu, 29 Nov 2007 17:50:36 -0600, Cecil Moore wrote: The measured delay through my 75m bugcatcher coil is 25 nS. In one case, the measurement "cannot be done," and in another case 6 minutes later it can be done; and the difference all because of one "particular" coil? That is 1. the first coil is one mighty particular coil; or 2. no measurement was done for the second, not so particular coil. Of course, for those who readily admit that English is not their best language of communication (and their writing tends to support that excuse); then we could be encountering: 1. another meaning, generally unknown or archaic, for particular; or 2. another meaning, generally unknown or archaic, for measurement; or 3. both. My bet is the answer will not hinge on blaming poor spelling, failing eyesight, a slip in thought, or the wrong meter setting (rubber crutches of the past), but ultimately a novel definition of the word "measurement" which will reveal a visit to the bench is superfluous to the conceptual clarity of it all = intellectual mooching. Of course, a novel definition of particular would amuse us all.... |
#5
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Richard Clark wrote:
In one case, the measurement "cannot be done," and in another case 6 minutes later it can be done; and the difference all because of one "particular" coil? Good Grief! I cannot do the measurement on the W8JI coil because I don't have the coil. Upon the coil that I do have, a 75m bugcatcher coil, the measurement was easy. -- 73, Cecil http://www.w5dxp.com |
#6
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On Fri, 30 Nov 2007 17:09:42 GMT, Cecil Moore
wrote: Richard Clark wrote: In one case, the measurement "cannot be done," and in another case 6 minutes later it can be done; and the difference all because of one "particular" coil? Good Grief! I cannot do the measurement on the W8JI coil because I don't have the coil. Upon the coil that I do have, a 75m bugcatcher coil, the measurement was easy. My goodness, it has been a long time since I've heard "Hearts and Flowers" attempted through posting on this newsgroup. How sad! It must be a titanic struggle to find the W8JI coil's description and build one. All the more strange for this shortfall given: On Wed, 28 Nov 2007 13:25:34 -0600, Cecil Moore wrote: http://www.w8ji.com/inductor_current_time_delay.htm No doubt your eyes are failing, or memory has lapsed momentarily, or perhaps a recent personal crisis diverted your attention - or more likely (and here we can all agree) the topic is utterly boring except for these charming flirtations you offer (otherwise considered to be intellectual pan-handling). Anyway, the "suggestion" of measurement of a time delay in the quote above is nothing more than that - a suggestion. If we were to press for more details (always absent in these proclamations passing as technical content), then we would find that, no, the measurement was one of resonance (and likely not even that) which then through a weak chain of rusty links of logic once again summons up the corrupted reading of Corum(s) to INFER not measure. I think the group was short-changed on the lack of a definition for the amusing application of "particular." At least we would have gotten some value added to drape the coffin of this thread. |
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