If you are serious about keeping it at 600KHz separation ten you will need to have real duplexors. You can get them in an enclosure with the three required connectors. The biggest issue other than their size will be possible de tuning when transporting. 440 is a better choice. Another option is to make a 440 repeater and connect it to a VHF simplex radio, this would allow you to put it at a remote location that is high and talk to all of the other users. You would also have a cross band repeater as well since a lot of people now have dual band hand held radios.. Stan
--- On Thu, 10/8/09, Doug Bade <[email protected]> wrote: From: Doug Bade <[email protected]> Subject: Re: [Repeater-Builder] Question on portable repeaters To: [email protected] Date: Thursday, October 8, 2009, 8:04 AM Possible options ????? I decided to poke around on the Bird TX/RX website and found this "little" guy ( relatively speaking :-) ) Probably more command post sized than SUV sized but hey.. how big is that SUV :-)??????? http://birdtechnolo gies.thomasnet. com/item/ all-categories- duplexers- and-triplexers/ duplexers- 2/28-37-04c? &seo=110 At 9.5 x 19 x 10.5 inches, COULD fit in a car.. It is rated at 65db at .5mhz.... so would be a bit better at .6mhz and as I recall many of the little mobile duplexers are typically 65db to 80db at best....so would be in the neighborhood of lowest useable isolation figures, depending on how quiet the TX is to start with. It looks like it gets to 70db at 1 mhz with less insertion loss so .6 mhz would likely be somewhere in between... if you do not mind the insertion loss... Assuming we could split, it at worst case, 10-20db of antenna isolation in a mobile environment might be possible, and/or some additional notching...all this may make a low power 2m portable duplexer "plausible" without filling a whole car....:-) Our club uses a 300khz 6 can TX/RX for our 2M repeater that was rated at ~100db at 600khz.. but when we had it set up for 600khz spacing it yielded in excess of 120 db TX to RX as delivered from TX/RX. >From a practical perspective "small" 2M duplexers seem to start at about 2Mhz split... but hey size is relative !!!! Doug KD8B > 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
