My really rough guess is that you will need around 85dB of isolation between the two stations. Using two antennas 25 feet apart is only going to give you about 30dB of isolation. A bandpass filter at .64Mhz off the center frequency will only give you around 10-20 dB more of isolation. I think you will need either a bandpass/bandreject filter, or possibly a notch filter on each station.
My math is all best-guess, so please verify it before you go buying equipment. I use a TX/RX Vari Notch 10" cavity for a similar application, but they are expensive. I don't think you sare going to find a cheap fix. Someone with more math skills can possibly verify my guess. 73, Joe, K1ike On 7/22/2010 7:10 AM, Kc7hgn wrote: > I am not going to be able to stack the antennas. They Would be about 25-40 > feet apart horizantal. I guess what I need is 2 bandpass filters. I think > thats what I am looking for. Now the big question. Can I build them? And > where would I find the information? If I can't build them, where would be an > inexspensive place to buy them? I don't know of any Elmers in my area that > know about bandpass filters, or one that would take the time to help. Thats > why I am here. > Thanks, Kevin > Kc7hgn > >
