jaya000 Posted January 23, 2007 Report Share Posted January 23, 2007 I hv this VHF preamp. I want to modify so that it can be used for FM 88-108Mhz. I want to change the input output filter. But i want to study the circuit first. Hence i hv downloaded & atttached .s2p files of the devices used. But they just start from 100Mhz. I want to know how the designer has designed circuit & calculated input output impedance? On this basis how he designed VHF filters for preamp 48-230Mhz with 28db gain? I hv just not calculated/tested the ferrite choke value. I hv collected even the datasheets of the devices used. If required i can post it here. I am newbie to RF, hence expecting experts here to put some light on the circuit used. preamp.rar Quote Link to comment Share on other sites More sharing options...
jaya000 Posted January 26, 2007 Author Report Share Posted January 26, 2007 Surprised to c that there is no reply. There is another posting regarding FM transmitter. This can be also a small transmitter if designed for FM then connected with suitable antenna with little circuit modification. Quote Link to comment Share on other sites More sharing options...
AN920 Posted January 26, 2007 Report Share Posted January 26, 2007 Analyzing something like this normally involves smith charts and lots of complicated calculations. It may be difficult for someone to fully explore on this board. Quote Link to comment Share on other sites More sharing options...
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