At 10:47 AM 1/16/05, you wrote: >I am sure this has been asked before, but I did a search archive on >the subject and came up with 0. I have a GR 300 repeater with no >duplexer, so I need 2 antennas. I tried a Larson mobile antenna w/ >the ground radials as the receive antenna and the same for the tx >antenna. These are mounted on a Station Master type antenna tube >(the guts were pulled out because it was untunable for 2 meters). >The rx ant at the top and the tx ant at the bottom, about 12' to 14' >separation. The system would talk to it self. I removed the tx ant and >replaced with a 4 ele yagi - works good. I need a omni ant for both >rx and tx. I have an Isolator on the tx and a Bp cavity and a >circulator on the rx. Why would it desense with one ant and not the >other ant? I know the idea behind the yagi and the mobile ant. But >they both have rf going vertical. I need to have minimal separation >without it talking to it self. Your ideas? Thank you. > >Rod
First you do not have enough isolation. Your antennas are too close. You will probably end up using two antennas separated by a LOT more space. Look at <http://www.repeater-builder.com/antenna/separation.html>, and the other repeater antenna articles at www.repeater-builder.com Second, what kind of feedline are you using? Unless it's 100% shielded (and don't mean 99%, I mean 100.000%) there will be some leakage. If the two feedlines are side-by-side up the tower, and are at all leaky, you have a long, narrow, coupling path. Been there. I helped a beginner who had put up a 2m repeater in his garage with two long runs of CB-grade RG-8... to two antennas at 40' and 70' on his dad's HF tower... and wondered why it desensed itself. Mike WA6ILQ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
