Peter, The only viable solution for a portable repeater on 2m is to use two widely-spaced frequencies, low power, and a compact base-station duplexer. Here in Central and Southern California, TASMA has wisely set aside two frequencies (144.930 input and 147.585 output) exclusively for temporary portable repeaters. The 2.655 MHz separation means that a small duplexer such as the Celwave 5085-1 can be used at low power, say 10 watts. I have just such a repeater in the final stages of construction, using a Motorola R1225 VHF duplex radio running about 8 watts- more than enough for emergency communications. The complete repeater is in a Pelican-style case that is about one cubic foot and weighs about 15 pounds.
Separate antennas is really not an option here. Even with just 10 watts of power, the horizontal separation needed to avoid desense is over 9,500 feet horizontally or 150 feet vertically. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Peter Dakota Summerhawk Sent: Wednesday, October 07, 2009 4:15 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Question on portable repeaters Morning, We are looking at building a portable repeater for special even use. This will be mobile mounted and 2M. My questions is this: If we are using two radios (one for TX one for RX) then what does the antenna separation have to be for all of this to work? Planning on mounting this in a SUV so roof space can be adjusted if need be. Thanks Peter Dakota Summerhawk Laramie County ARES
