At 07:30 PM 1/24/05, Dave Gingrich <[EMAIL PROTECTED]> wrote: >On Jan 24, 2005, at 18:28, w9mwq wrote: > > > Ok, I know this sounds silly, but my repeater is now hearing better > > than it transmits. Here's the setup, the the issue. I have a > > Maggorie (no comments) HiPro transmiitter running 2 watts into a > > Vocom Amp running 160 Watts into the duplexer, 130 out to the > > antenna, fed with 7/8" hardline into a Diamond Dual Band Antenna at > > 92'. VSWR is 1.1:1, with 130 watts forward and 1/10 watt reflected > > at an impedance of 52 ohms, (MJF 259). > >I would vote for a failure of the Diamond antenna. I would bet one or >more sets of the set screws holding the elements together have come >loose. When this happens, the antenna will still present a perfect 50 >ohm load, but perform poorly. Diamonds are okay antennas when they are >new, but they have to be taken down every year or two, disassembled, >cleaned and tightened up. Really only a decent antenna if you can get >to it conveniently for the annual repair. You will never see this type >of failure with the wattmeter or impedance bridge.
The article at <http://www.repeater-builder.com/antenna/cracking.html> may be of interest. While it is not exactly relevant to w9mwq's situation (i.e. it describes duplex noise that shows up as crackling), it does describe a broken fiberglass colinear antenna having elements disconnect and connect thereby changing gain levels. Mike WA6ILQ 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/
