Right on the money Scott... many times the antenna and/or feed line can be the trouble maker. Although not practical in many cases... a 50 ohm test termination at the top end of the feed line can tell you a lot...
Knowing the "effective sensitivity" at the site is a big deal often overlooked by the more informal repeater owner/operator. cheers, s. > "Scott Overstreet" <[EMAIL PROTECTED]> wrote: > > John--- > I don't know if you have done the following yet but if not > you should. Put an iso-T in front of your receiver and do > a simple desense test using your signal generator into > the iso-T. Set the generator for a couple of kc, deviation > at 1 kc so that you can easily recognize it. Run the signal > level down to where you can just hear it in the receiver > with the transmitter off. Turn your transmitter on. Do you > still hear your generator signal? Lets assume you don't as > if you do you don't have desense. > > Now, remove your antenna feedline from your duplexer and > put a good screw on dummy load in it's place and repeat > the above test. Do you still have desense? If yes, you > have insufficient duplexer performance to support your > transmitter (power and sideband noise spectra) or leaky > interconnect cabling. > > If no, you are getting desensing from either your feedline > or your antenna or something your antenna radiated signal > is exciting like a rusty tower joint or joints which is > or are producing wideband noise which your antenna is > hearing and feeding back to your receiver as a desensing > signal. If this looks to be the case, put the dummy at the > end of your feedline in place of your antenna and repeat > the testing. This should leave you with either a feedline > or connectors to replace or a possibly bad antenna. > > I've been this far and found a corroded Hustler. Took it > down, cleaned it up and put it back as a replacement was > not immediately available----it is still up and working as > well as it ever did with absolutely no desense.
