well richard,i made a mistake here it is a 210/A4 external harness i have done it in the past ,one of my freind gave me one day an A4 that had a broken dipole and since we didnot have any spair dipole w decide to match 2 to become an 210C2 . and it worked ,i think we used rg/11 coaxial,,,,,,,humm about 11 inches,,man it is long ago.
i will do it once more ,i shell use this MFJ 259 73/s Richard and all reading us,it is a great discussion and instructive gervais ve2ckn ----Original Message Follows---- From: va7aa <[EMAIL PROTECTED]> Reply-To: [email protected] To: [email protected] Subject: Re: [Repeater-Builder] Double the gain or double the power? Date: Wed, 31 May 2006 19:16:52 -0700 Not 100% sure of what you want Gervais... are you looking to splitting a 210-C4 in half to create two 210-C2 's? Why? You don't modify the Z you match whatever is presented to you. That'll be a lot of work. The harness in the Sinclair 210-C4 is mounted internal within the support mast.... so it might be a bit of a trick... you'll have to take it apart big time. At some point inside the support mast the "top" two dipoles are phased by coax with the bottom two dipoles...don't know what Z that coax is. But that's where you would split them. one thing though, if you parallel two feelines that present 100ohms, you can feed it with 50 ohms.. and away you go with your RG8u....NO?? But with the Sinclair design I am not sure that the interconnection cable presents 50ohms at the point the top and bottom pairs are joined... if it is your away to the races... should but not 100% sure as I have never taken one apart. I have made up many 4 and 8 pole collinears in my day but I have always used 1/4 wave multiples of RG11U as required.... 1/4... 3/4.... 5/4...any odd multiple, velocity factor considered, is acceptable. Gervais...remember the loops themselves contain the "balun" as the loops being folded dipoles are supposed to be 300ohms balanced at the feedpoint...so feeding em with coax first requires a "balun".. that balun should take it down to 50 ohms then the phasing harness interconnects the individual dipoles.. Gervais... measure the dipoles... they should be between 18-20" if for low VHF cut... if they are only 16" they are too short to be of any amateur use. Finally have a look at the tail... is it RG8 or 213U or is it RG11U... if it is RG11 you will probably have a problem as the tail must NOT be cut or changed ... it is a phasing stub. This is common on some beams matching the 300ohm driven element but they have been so many versions over the years... you never know. Any other thoughts? VA7AA ----- Original Message ----- From: "gervais fillion" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Wednesday, May 31, 2006 5:37 PM Subject: Re: [Repeater-Builder] Double the gain or double the power? > Richard > would you have the shematics of the modification of a "separate 210c4" > i have here an c4 here that i will modify into 2 210c2 but i dont remember > the point where you modify for the impedance,,,matching the 2 loop from > 100 > to 50 ohms > > i did it in the past but so long ago > > 73/s all thanks for the qsp > > gervais,ve2ckn > bic,quebec > > > ----Original Message Follows---- > From: va7aa <[EMAIL PROTECTED]> > Reply-To: [email protected] > To: [email protected] > Subject: Re: [Repeater-Builder] Double the gain or double the power? > Date: Tue, 30 May 2006 10:33:22 -0700 > > 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 > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.394 / Virus Database: 268.8.0/353 - Release Date: 5/31/2006 > > Yahoo! Groups Links 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/
