Not always true. Even if a duplexer presents a flat 50 ohms at the operating frequency to a transmitter, the transmitter may not work properly and you may have to experiment with different lengths of cable between the transmitter and duplexer. The reason is that off frequency the duplexer can be highly reactive and that off frequency reactive load is seen by the transmitter as well as the flat 50 ohms on frequency and some transmitters don't like any reactive load on the finals. They will not load properly and you will not get full power out. Sometimes spurs will be generated by the off frequency reactive load. Now if there is an isolator on the transmitter then the transmitter always sees a flat 50 ohms regardless of what the duplexer is presenting and in that case the length of cable makes no difference.
73 Gary K4FMX > > The only time that you need specific lengths of cable between pieces of > equipment is to cover up an impedance problem. If the impedances are > correct on the inputs and outputs of the devices that you are connecting, > the length of the proper impedance cable is immaterial. > > 73 > Glenn > WB4UIV > > > > At 05:39 AM 06/04/07, you wrote: > >Hi guys .I have been wondering and trying to find out the correct length > >of coax between the diplexer and the tx.and rx and someone has brought it > >up on another group.here is a snipit > >Is the length between the exciter -pa-TX on duplexer a quarter wavelength > >or multiple there of. Is the rx-preamp(Is the rx-preamp(if used)-rx input > >of duplexer the same number of wave lengths as the TX path > >So hopefully this will help answer the above enquiry. > >Thank You, > >Ian Wells, > >Kerinvale Comaudio, > ><http://www.kerinvalecomaudio.com.au/>www.kerinvalecomaudio.com.au > > > > > > > > > > > > Yahoo! Groups Links > > >
