On 5/21/2010 10:28 AM, kc0mlt wrote: > Hello all. > > I am trying to figure out if the duplexer we have put together is up > to the task or not. Here is the situation. We have four cavities 6.5" > dia. one is a vari-notch the others are simple reject cans. Two > rejects are on the TX side and one reject and the vari-notch are on > the RX side. All set and tuned with rg-213 jumpers between cans and > RG-142 from the cans to the Tee connector. We are doing some light > testing with a cheap dual ban antenna on the garage. It is feed with > RG-8 about 70 feet. We are having some issues with receive. It kind > of sounds like desense but I think it is something wrong with the > receiver. I was just wondering if the cobbeled together cans sound > like thay are doing a good enough job as a duplexer or if we do have > something to change on it. The repeater is only putting out 2 watts > for testing. I would think I have enough separation for that power > level. Any suggestions or thoughts woyuld be greatly appreciated. > > Thanks Wade KC0MLT
Dump the RG-213 and RG-8 and use at least RG-214 between cavities, or 1/2" hardline on the run up to the antenna. RG-8 and -213 are single shielded and do not provide adequate isolation. You need 100% shielding. Also find a GOOD dummy load, and substitute that in place of the antenna. If you still have the problem, there is an antenna issue.
