Amateur big loads

Description:Installing the tuner between the feed line and the antenna allows for the feed line to see a load close to its characteristic impedance, while sending most of the transmitter's power a small amount may be dissipated within the tuner to be radiated by the antenna despite its otherwise unacceptable feed point impedance. In this case, the computed results are largely meaningless. Other instruments, such as network analyzers, low power directional couplers and antenna bridges use low power for the measurement and must be connected in place of the transmitter. In this mode the diode and its associated filtering capacitor produce a voltage that is proportional to the peak of the sampled voltage. By using directional couplers and a bridge in combination, it is possible to make an in line instrument that reads directly in complex impedance or in SWR. This method is used at VHF and higher frequencies.

Views: 3478 Date: 2018-12-16 Favorited: 79