EEVblog Electronics Community Forum

Electronics => RF, Microwave, Ham Radio => Topic started by: A.Z. on November 04, 2024, 08:46:54 pm

Title: voltage and current transformers
Post by: A.Z. on November 04, 2024, 08:46:54 pm
I kept wondering why, aside losses, some people doesn't consider using both for some types of antennas; let's take a dipole or a loop (delta or quad, whatever), now imagine feeding it with a voltage transformer (galvanic) so that the radiator won't have a direct DC reference to ground: add a current transformer after it,  to balance feedline currents, and we'd have a pretty good setup imVVHo, so... why not ?
Title: Re: voltage and current transformers
Post by: iMo on November 04, 2024, 09:08:30 pm
Because two transformers are heavy, for example..
Title: Re: voltage and current transformers
Post by: Geoff-AU on November 04, 2024, 10:15:46 pm
A fully isolated antenna builds up static electricity as the wind blows, this creates RF noise and risks damaging your radio when the charge exceeds the transformer's voltage rating and jumps across.

There's really no point in a 1:1 voltage balun.  Just a current balun or RF choke to make sure the feedline doesn't take on extra duties.