You will have 20dB-30dB loss from antenna to transmit port. About the only way to implement a circulator in a half duplex radio is to tap the PA board before the T/R switch, and if it is PIN diodes, it still may create a mix.
On Mon, Nov 2, 2009 at 1:40 PM, Paul Plack <[email protected]> wrote: > > > Can you receive through a circulator without heavy losses? I've never tried > it... > > > ----- Original Message ----- > *From:* David <[email protected]> > *To:* [email protected] > *Sent:* Monday, November 02, 2009 1:31 PM > *Subject:* [Repeater-Builder] Re: Weird Interference between APRS and 2-M > repeater help needed > > > > First of all you do not have enough isolation between antennas with only > two wavelenghts horizonal seperation. A single bandpass cavity will not be > enough. I would try 2 bandpass/bandreject cavities. Reject set for the TX > freq and the other set for the RX freq. I believe that RF from your repeater > is exciting the RF amp in your aprs tranceiver, see if the problem is still > present with the aprs hooked up to the antenna but with your power supply > disconnected. Most people used a simple mobile for aprs which creates alot > of headaches where several transmitters are used. They just dont have the > filtering needed for this application. You should also use a circulator on > your aprs radio. This will help keep RF out of your aprs transmitter. > > David Epley, N9CZV > Winchester, In > > . > > > >
