Kenwood TS-780 Instruction Manual

Also see for TS-780: Service manual Instruction manual Instruction manual

~ @ Adjustment (SWR)Your antenna must be connected to a 50 ohms coaxialcable, since the antenna impedance of the TS-780 is50 ohms. Also, the antenna must be adjusted to50 ohms impedance. This adjustment is called im-pedance matching.Proper impedance matching is accomplished by check-ing SWR (VSWR: Voltage Standing Wave Ratio) using aSWR meter. Ideal SWR is 1:1.The SWR meter should be connected between theantenna feeder and the antenna terminal at the rear ofthe transceiver, whichever is more convenient. Notethat the reading of SWR meter varies somewhat depen-ding on the location of connection because of the loss inthe antenna cable. This is particularly noticeable whenthe antenna cable is more than 10 m long.An antenna system which shows a standing wave ratioof less than 1.5 will insure satisfactory transceiveoperation.4-2. COAXIAL CABLEFor satisfactory transceive operation, coaxial cablemust be used. When the transceiver is used for fixed sta-tion service, the coaxial cable becomes relatively long, solow loss (large sized) coaxial cable of the shortest possiblelength should be used, as the loss of coaxial cable cannotbe neglected when operating in high frequency bands, par-ticularly in 144 MHz or higher bands.When the coaxial cable needs to be extended more than10 m, use one of larger size such as RG8/U or UR67.AntennaAntenna-feeder XpKOLO0xZNCoaxial cableWhen SWR meter is connected as shown above, the actualSWR at the antenna feeder is higher than 1.5 because of theloss of the coaxial cableFig. 7 Adjustment of Antenna SystemAntenna feederANT terminal {/Fig. 8B. Antenna installation1 Ground planeantennaAntenna feederSWR' at antenna feeder shouldbe less than 1.5: 1 Antennafeeder should be waterproofed.= 24-row horizontalstack (4 parallelelements)Ideal type of antennaCoaxial cable10