Bob, Sorry if I didn't get it right but now I am really confused .... and open to learn.
<Snip and paste> > Shielding percentage of the antenna feedline has nothing to do with duplex > suitability. Somewhere I am missing something.... If shielding doesn't play a part in the suitability factor of selecting feedlines, why do we use hardline (other than less loss) or double shielded jumpers for connections etc.in a duplex operation? What I was refering to was mainly about desense and the use of feedlines that do not provide proper shielding plus ongoing discussions on the group about the noise generated by 9913 due to dissimilar metals and flexing and therefore not the best choice as you also pointed out. Was my comment ...... >>As mentioned by others ... a change to >>some other type of a 100% shielded feedline will probably do wonders for >>your receive problem. ......wrong or just not stated properly and misleading? What am I missing? Thanks Larry ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, January 05, 2006 10:20 PM Subject: Re: [Repeater-Builder] Repeater Assistance in Michigan. > At 1/5/2006 21:55, you wrote: >>I am not the most knowlegeable person but noticed a couple of comments >>about your feel line without an explaination. >> >> >Feedline = RG8, mentioned 9913 when I went to the shop but the coax has >> no markings on it when I got it so >I'm not quite sure if I got it or not >> :) >> >>RG8 is not suitable for duplex operation. There is insufficient shielding >>and will most likely result in receiver desense while the transmitter is >>operating. You might look back in the archives on the Repeater-Builder >>there has been extensive discussions about this problem and also on the >>use of 9913 for duplex operation. As mentioned by others ... a change to >>some other type of a 100% shielded feedline will probably do wonders for >>your receive problem. >> >>Good Luck >>Larry > > Shielding percentage of the antenna feedline has nothing to do with duplex > suitability. 9913 is 100% foil shielded. The problem is the type of > shield metallization used. Silver-plated RG-214 can be used but is just > as > lossy as RG-8, so not good for long lengths. > > Given your operating frequency & required cable length, I'd go with 1/2" > Heliax or some other solid-shielded feedline. > > Bob NO6B >>----- Original Message ----- >>From: <mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED] >>To: >><mailto:[email protected]>[email protected] >>Sent: Thursday, January 05, 2006 8:18 PM >>Subject: Re: [Repeater-Builder] Repeater Assistance in Michigan. >> >>I'll try what Eric mentioned when I get a chance to go out to the site... >>as for now, I'll try to answer Mathew's questions... >> >>Antenna Height = 27.0m, rooftop tripod >>HAAT = 16.4, elevation gains going south but drops quite a bit going >>north. >>Gain = purchased an Antenex FG1523, 3dB Fiberglass Omni >>Feedline = RG8, mentioned 9913 when I went to the shop but the coax has no >>markings on it when I got it so I'm not quite sure if I got it or not :) >>Power of Transmitter = 50w, 35w after duplexer >>Duplexer = Sinclair MR256B*2 - Mobile Type, tuned by shop >>VHF-Hi, 152.8850 & 159.5400 >> >>Thanks! >> >>-----Original Message----- >>From: Mathew Quaife <[EMAIL PROTECTED]> >>To: [email protected] >>Sent: Thu, 5 Jan 2006 18:47:36 -0800 (PST) >>Subject: RE: [Repeater-Builder] Repeater Assistance in Michigan. >> >>It would be helpful to know how high the antenna is, gain, feedline and >>power of the transmitter, and as Eric said, what type of duplexers, >>etc....Are we dealing with VHF or UHF? >> >>Mathew >> >> >> >>Eric Lemmon <[EMAIL PROTECTED]> wrote: >>Since a repeater's range is limited *primarily* by its ability to receive, >>you should concentrate on those factors which directly affect receive >>sensitivity. One of the most common problems is the use of a duplexer that >>has insufficient isolation for the combination of transmitter power and >>receiver sensitivity. A transmitter PA that produces a "dirty" signal (one >>with spurs) coupled with a broadband receiver will require much more >>isolation than a pure-carrier tube PA and a very narrow-band receiver. >> >>Does the range improve if you reduce transmitter power to, say, 20 watts? >>Does the range improve if you remove any preamplifier on the receive side? >>Does the range improve if you put a single bandpass cavity with 1.0 dB of >>insertion loss between the duplexer and the receiver? Is the duplexer >>*known* to be properly tuned? >> >>73, Eric Lemmon WB6FLY >> >> >> >>-----Original Message----- >>From: [email protected] >>[mailto:[EMAIL PROTECTED] On Behalf Of kfd29 >>Sent: Thursday, January 05, 2006 3:29 PM >>To: [email protected] >>Subject: [Repeater-Builder] Repeater Assistance in Michigan. >> >>Looking for assistance w/ a new repeater system in GR, Michigan... Could >>use >>a hand in finding out why we can not pick up 5 watt handhelds only 5 miles >>out, maybe we missed something in setup? If anyone is knowledgable in >>troubleshooting repeaters or in the GR area, please contact me! Small >>business that can't quite afford the $70/hr charge for a tech right now >>lol. >>Thanks! >> >> >> >> >> >> >> >> >> >> >> >> >> >>Yahoo! Groups Links >> >> >> >> >> >> >> >> >> >> >>Yahoo! Photos >>Ring in the New Year with >><http://us.rd.yahoo.com/mail_us/taglines/photos/*http://pa.yahoo.com/*http://us.rd.yahoo.com/mail_us/taglines/photos/evt=38087/*http://pg.photos.yahoo.com/ph//page?.file=calendar_splash.html&.dir=>Photo >>Calendars. Add photos, events, holidays, whatever. >> >> >> >> >> >> >> >>---------- >>YAHOO! GROUPS LINKS >> * Visit your group >> "<http://groups.yahoo.com/group/Repeater-Builder>Repeater-Builder" on the >> web. >> * >> * To unsubscribe from this group, send an email to: >> * >> <javascript:parent.ComposeTo('[EMAIL PROTECTED]');>[EMAIL PROTECTED] >> >> * >> * Your use of Yahoo! Groups is subject to the >> <http://docs.yahoo.com/info/terms/>Yahoo! Terms of Service. >> >> >> >>---------- >> >> >> >> >> >> >> >> >> >>---------- >>YAHOO! 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