Comment on “Compact envelope dark solitary wave in a discrete nonlinear electrical transmission line” [Phys. Lett. A 373 (2009) 3801–3809]

• RWA method based investigation of modulated waves in an NLTL.
• Derived NLS type equation contains more terms than earlier reported.
• NLS coefficients strongly depend on NLTL parameters than earlier reported.
• Nonlinear dispersive elements are not indispensable to support compact solutions.

We revisit the derivation of the equation modeling envelope waves in a discrete nonlinear electrical transmission line (NLTL) considered a few years back in Physics Letters A 373 (2009) 3801–3809. Using a combination of rotating wave approximation and the Gardner–Morikawa transformation, we show that the modulated waves are described by a new type of extended nonlinear Schrödinger equation. In addition the expressions of several coefficients of this equation are found to be strongly different from those given earlier. As a consequence, key relationships between these coefficients that sustained the previous analysis are broken.