Kenwood TS-780 Instruction Manual

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

Contents

0 Adjustment (SWR)Your antenna must be connected to a 50 ohms coaxialcable, since the antenna impedance of the TS-780 is5 0 Ohms. A l s o , t h e a n t e n n a m u s t b e a d j u s t e d t o50 ohms impedance. This adjustment is called im-pedance matthing.Proper impedance matthing is accomplished by check-ing SWR (VSWR: Voltage Standing Wave Ratio) using aSWR meter. Ideal SWR is 1: 1.The SWR meter s h o u l d b e c o n n e c t e d b e t w e e n t h eantenna 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.I’ t ’1 Coaxial cableW h a n S W R meter is c o n n e c t e d a s shown above. t h e actualSWR at the antenna feeder is higher than 1.5 because of theloss of the coaxial cableFig. 7 Adjustment of Antenna SystemAntenna feederANT terminalFig. 88. Antenna installation1 Ground p l a n eantenna4-row horizontalStack (4 parallelennaTower