I don't think the VK1OD calculator includes the effect of the dc resistance of the wire. In the limit at low frequencies the loss should approach the dc loss. VK1OD's calculator doesn't do that. It continues to calculate loss getting lower and approaching zero as frequency gets lower. That can't happen. With copper clad wire, especially when the plating is thin, there can be a huge effect at low frequencies. In the case of Wireman 551 on 160 meters, I think most of the current is flowing in steel.
I haven't done a rigorous analysis of the accuracy of TLDetails, but it seems to produce more sensible results that any other calculator I have seen.
Jerry, K4SAV
You don't have to guess about the loss model in TLLC works, it is declared down the page from the input form, and there is considerable discussion about the limits of validity of the loss model.
There are also warnings about the error introduced by extrapolation beyond the data on which the loss model is based.
There is another page on the site that discloses enough information about how the three TL calculators work that they could be copied.
So, rather than guesses and misinformed comment, just read the relevant material.
All of these tools calculate some kind of model of the real thing. The real thing is a manufactured product with manufacturing tolerances, and its characteristics vary with temperature, installation, and through life. If you think that a modelling tool that does not for instance take into account the fact that RG58CU is stranded in plated conductor centre conductor, and tine plated braided shield rather than a solid copper cylinder approximation, then don't use them.
I often attempt to reconcile TLLC etc with other tools, and dig down to identify the differences. One of the ways in which TLLC differs from most tools is that it adjusts both Ro and Xo for frequency, and differently to ALL other tools I have checked, it also assumes that there is a frequency between DC and daylight where Zo equals nominal Zo, eg that at some finite frequency, Zo for RG58CU will be equal to 50+j0.
If you feel more comfortable with the ARRL charts or tools, use them.
If you find that TLLC does not agree with published manufacturer's data at some frequency within the declared model frequency range (it is on the results form), let me know.
I originally wrote TLLC etc for my own use, and I recognise that they produces too much information for some users who are more comfortable with a simpler view of the world. That is fine. Nevertheless they get towards a million uses per annum... so hopefully some of the users are applying them with validity.
As for extrapolation of Wireman CCS ladder lines to low HF, it is likely to be in significant error. The model data was measured from 10 to 100MHz where the effect of CCS conductors would not be significant, but that changes at low HF, especially for the premium 19 strand CCS versions which I expect will have significantly higher loss than the extrapolated results.
Owen
