TLW v3.24 checkout

I am often asked for recommendations for a replacement for TLLC (Duffy 2001).

The announcement of an update to TLW by ARRL / N6BV in June 2014 QST flagged a possibility.

Screenshot - 13_05_2014 , 15_58_04

Reviewing the available cable types, Belded 8215 (RG-6/U type) was tested for loss with a 75+j0Ω load (approximately a matched load) at 1MHz, and the result of1.147dB does not reconcile with the Belden datasheet showing 1.3124dB, an error of -13%.

Screenshot - 13_05_2014 , 15_58_04

Using the same line, a scenario of load impedance of 750+j0Ω (10:1 VSWR) on a 1m length again at 1MHz shows negative loss, ie more power out than in… which of course is not possible for a passive network. Curiously, the loss due to VSWR is 0.012dB, which implies that matched line loss was -0.001-0.012=-0.013dB… again nonsense!

References

  • Duffy, O. 2001. RF Transmission Line Loss Calculator (TLLC). VK1OD.net (offline).