Aaron.. Not sure where in Alberta your at... but here's what we did here on the Coast when we came up with that "problem". I think I know what you have Aaron... you are describing one of those older Sinclair antennas that had two separate 2 bay collinear antennas integrated into the same mast... we had one here... but be careful with that antenna.
First check to make sure both bays (or sets) are cut the same... better to sweep the antennas or at least put some power into them and check the reflected power @146.00mhz . Unlike the Sinclair antennas of today those older collinear antennas often had a fairly narrow bandwidth... if they were cut 160 -174mhz (as ours were) your outa luck... 148-160mhz your in luck... they will work ok at 146mhz ok.... before putting this antenna up check the vswr or reflected power with a Bird wattmeter....it should be around 1 maybe 2 watts returned for 25 in as there will be little return loss with no long fedline.... if you see 5 watts or more there is a problem. Aaron... there is no loss when you PROPERLY co-phase the (2) 2bay antennas together... there will be a net gain of 3db... 4 bays will give you approximately 6db omni or 9db cardioid offset.... so put the 25 watts into it... your ERP (effective radiated power) will be 100 (6db omni) or 200 watts (9db offset) You can try -phasing those two antennas together by making up a simple phasing harness of 2 chunks of about 11.5" of RG11u (75ohm) cable (.66 velocity factor @146.00mhz)... this might work. I said might work because you never 100% know for sure in an arrangement like this, the phase relationship of the INDIVIDUAL diploes with each other... this will probably work great...but do a careful before and after check with a distant station.... so this part becomes a bit of a trial and error process.... if the 2 sets of dipoles wind up somehow being out of phase with each other there will be a net loss... if they are in phase there will be a net gain of 3db. Unless your antenna is going up 300' on a broadcast tower... this is pretty easy thing to try... just make sure everything is taped up and heat shrinked when your finally finished. Richard VA7AA www.islandtrunksystem.org (don't mind talking to you on the phone about this... 250-244-1636 I have free LD calling so I can call back) ----- Original Message ----- From: "atms169" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, May 29, 2006 9:45 AM Subject: [Repeater-Builder] Double the gain or double the power? > Easy question for all other repeater owners. What should I do? > > I have a pair of folded looped-dipole antenna's for my repeater which > pushes 42 Watts. Once I add the antenna and duplexers I get 25 Watts > output. The antenna has 4 looped-dipole antenna's with phasing > harness but I only use one set. > > So what should I do, should I continue using the 1 set of > looped-dipole antenna's at 25 Watts or do I add the second pair of > looped-dipole antenna's and push only 10 Watts out on the repeater (As > there will be a loss). > > Which would be better? I am sure I am doubling the gain for PEP. > Would I have a better receive on the antenna as well? Would it really > make it stronger? > > Aaron > VA6AE > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.394 / Virus Database: 268.7.4/351 - Release Date: 5/29/2006 > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
