Thanks for the replys everyone. That cleared it up for sure. I will go ahead and build the T to cavity cables to one electrical wave length for the other band. And is that ¼ wave plus velocity factor of cable? Which will be FSJ1. Here is some more detail on the system. It will go in stages. The final stage will be this remote receive setup with a UHF link on the bottom of the tower to the transmitter site. Also toying with a VOIP link with UHF as a failsafe. At this point the receivers are on separate antennas at the top of the tower, with 2 bandpass Sinclair 1-150-1S7 cavitys on the VHF, and one big Wacom cavity on the UHF receiver. The remote TX site hasnt been installed yet (waiting to find a MSR2000 UHF RX board for this divorced VHF TX site) so the transmitter is temporally at this site also. There are two bandpass cavitys DB4001s on this Mastr II transmitter with the antenna 40-50 feet down from the receive antenna. Sensitivity is shocking good right now with this setup. Very little RX loss, and very little desens. Will the receivers stay on one frequency as in a repeater receiver or do you need to move around each band a bit? Yes they will stay put. How much other RF is around? ... Does the site have a lot of transmitters and are any of the high power monsters as in the case of paging or broadcast? None in these bands! :-) But wireless ISP Ive found to be very noisy allover the place there. 50Mhz and up! Thanks again everyone! -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025 Sent: Tuesday, March 09, 2010 4:29 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Dual receivers on one antenna for RX only site
> "Ross Johnson" <kc7...@...> wrote: > Hello to the group, > My name is Ross KC7RJK This is my first post. Hi Ross, My name is skipp and I'm a junkoholic... "hi skipp" and I %#*^&.... scuse me, lost my mind for a moment. Moving along > Most questions are answered from that amazing and up > to date web site! I thank you all involved very very > much for that. We don't play up the RB web site nearly enough... we also don't let Kevin, Scott or Mike run with scissors. > Well here's the question I've found little and conflicting > info on the web about. So feel free to point me the right > way here. Simple, go west... better weather and less humidity. > Can a dualband antenna VHF/UHF for RX ONLY be fed to > two receivers one VHF, one UHF, without a quote "duplexer" > using a T instead? Of course, but it may not be the best situation. > Here's the idea. This is a remote RX site. The idea is > to run something like a beefed up X500 dualbander at tower > top, then 7/8 hardline 100 feet down to the receivers. > Both receivers will have one or two bandpass cavities > inline before the T. Would a duplexer be necessary in > this case. Or could it be done with proper cable lengths > and a T? Doesn't even need the special cable lengths.... but there is a reason for doing everything and here comes questions 101. Will the receivers stay on one frequency as in a repeater receiver or do you need to move around each band a bit? How much other RF is around? ... does the site have a lot of transmitters and are any of the high power monsters as in the case of paging or broadcast? If you don't have a lot of adjacent frequency operation going on there are two other options to consider. One is the Diamond or Comet type of band splitter, which actually would take the place of your T and be much better. Model CF-4160K http://www.universa <http://www.universal-radio.com/CATALOG/hamantm/cduplex.html> l-radio.com/CATALOG/hamantm/cduplex.html And another very nice option would be the DCI dual band filter Model: DCI-146-444-DB. http://www.dci. <http://www.dci.ca/?Section=Products&SubSection=Amateur> ca/?Section=Products&SubSection=Amateur And you can use the plain T, a more traditional signal divider and various combination of band-pass cavity layouts. > Thanks for your time and for the probably obvious > answer I'm not sure of. > Regards > Ross KC7RJK be more worried when you feel sure of yourself. cheers, skipp
