**BUG** Concise problem statement: The lossless transmission line does not run in EE. This explains why. The ngspice lossless transmission line allows the user to specify **either** Z0 and TD **or** Z0, F and NL. The EE transmission line specifies Z0, TD **and** F. The EE default value for F is 1. Deleting this *value* removes F from the list of Custom Attributes in the Properties panel *but* leaves: `F=` at the end of the parameters list for each instance of a T in the netlist. The netlist then fails to parse correctly so the simulation fails to start (with no clear error message to the user). Running the netlist in ngspice.com but with the `F=` parameter for each T instance deleted or commented out, the sim runs OK: http://www.ngspice.com/index.php?public_circuit=jtvRn7 How to fix this. **************** The simple way is to remove the F parameter and just have Z0 and TD as the only available parameters however for people doing RF design, the F and NL option may be more helpful. Maybe access the two options from a dropdown menu in the symbol in left hand panel (like the symbol choices for US/EU for some components)? For info: ********* From ngspice manual Chapter 6: Transmission Lines. http://ngspice.sourceforge.net/docs/ngspice-manual.pdf ________________ Z0 is the characteristic impedance. The length of the line may be expressed in either of two forms. The transmission delay, TD, may be specified directly (as TD=10ns, for example). Alternatively, a frequency, F, may be given, together with NL, the normalized electrical length of the transmission line with respect to the wavelength in the line at the frequency, F. F is specified in Hz. If a frequency, F, is specified but NL is omitted, an NL value of 0.25 is assumed (that is, the frequency is assumed to be the quarter-wave frequency). Note that although both forms for expressing the line length are indicated as optional, one of the two must be specified. Url: https://easyeda.com/file_view_Transmission-line_aOICUO6oh.htm Browser:Mozilla/5.0 (Windows NT 5.1; rv:25.0) Gecko/20100101 Firefox/25.0