Jeremy, You did not provide enough information to give you a good answer. How far apart are the frequencies involved? How powerful is the other radio?
What I can tell you right away is that vertical separation is far, far, more effective than horizontal separation. If both radios are going to be frequency-agile, that is, there may not always be a fixed separation in frequency, then the simple answer is: Separate the two antennas vertically as much as you can, one over the other, and hope for the best. Use double-shielded cable for feedlines on both antennas. Damage to the receivers is not likely, since most good radios have diode protection on the front ends. After all, look at almost any "mobile command post" vehicle, and you'll probably see a dozen antennas on the roof- usually no more than a foot or so apart. Although major desense is almost guaranteed when any one of the radios transmits, judicious use of preselectors (such as those made by DCI) can minimize it. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jeremy (KB1REQ) Sent: Monday, October 26, 2009 6:24 PM To: [email protected] Subject: [Repeater-Builder] Antenna spacing This post does not necessarily relate to repeaters, but some of the same calculations can be applied. I am interested in installing another two meter radio in my shack and was wondering what kind of spacing is needed as to not over load either of the radio's receivers. I currently have an icom set up on a j-pole, and I have a 45 watt GM300 that I want to add. What would be the best placement of antennas to reduce desense. or otherwise damage the receivers?
