Topband: Quarter wavelength stub as trap

[DAVID CUTHBERT]

Guido wrote:

Good night from Italy.
What do you think about using a quarter wavelength shorted stub, made with 
coaxial cable, as trap for an 80m + 160m inverted L?
15.6m of RG213, shorted at one end, will block 80m and will represent about 
50 OHM of XL on 160m 

This would work well if the line was not lossy. At 3.5 MHz the line loss is 0.19 dB and the input impedance of the shorted 90-degree line is 2300 ohms. 

    Dave WX7G