Hi Ted, regarding the IMU feeder, I remember that it was early designed with an internal diameter of 170mm. Later on it was reviewed to 165mm to achieve a better polarization circularity. Going down to 154 mm it is a big change so you would be exploring a new world. I guess you'll probably be able to get it to resonate at 1296 MHz meaning to achieve a somewhat acceptable return loss on the probes, but I have no idea or rather I really doubt that you will be able to achieve good circularity/isolation. This is for a W2IMU with screw polarizer. VE4MA with screws it follows the same concept. These are normally time consuming jobs so I'd really suggest you to start with the correct diameter if you can. Anyhow GL with your experiments. regs Sergio IK2MMB Ted Barnes ha scritto: -- Email.it, the professional e-mail, gratis per te: http://www.email.it/f Sponsor: Tomb Raider anniversary. Gioca con Lara Croft sul tuo cellulare! Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=8273&d=30-9 _______________________________________________ Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html