I just got a Celwave Duplexer from a guys storage. It's so rusted and covered with dirt it looked like it may of been on the Titanic. Anyway while removing the cables I noticed that the connectors were brass and starting to tarnish with the green powder stuff. And I had one of the male N connectors center pins stay with the female connector when I unscrewed it.
On Wed, Aug 20, 2008 at 7:44 PM, Scott Overstreet <[EMAIL PROTECTED]> wrote: > John--- > > I'm repeating my two previous messages to you on 8/3/08----they again seem > appropriate. > > Scott > > 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. > > > > Hello (Again) John---- > > Yes--It is necessary that you put the iso-T immediately in front of your > receiver----you want to be testing against the signal that is presented to > your receiver after all of the processing before it. > > A couple more thoughts---- > > Don't overlook the possibility that your duplexer is noisy or maybe I should > say fried. I have two 2 meter Phelps-Dodge duplexers here that on the > instruments show 110 db. Tx freq. attenuation into the Rx port as they > should but badly desense with transmitter power applied----they are > apparently internally bad connectivity wise----possibly adjusted with power > applied or just corroded internal finger stock. In any case, they make > wideband noise with transmitter power applied that is visible as a "hump" of > noise at the receive frequency when the Rx port on the duplexer is observed > by spectrum analyzer. And, one interesting fact is that this wideband > (desensing) noise is not easily detectable by listening to the audio from > the repeater receiver. In other words----If this sort of thing is your > problem----you may not hear any change just turning the transmitter on and > off----you must work against a modulated weak signal either into the antenna > or via an iso-T. > > > > > ----- Original Message ----- > > > > > > > > ----- Original Message ----- > From: John Transue > To: [email protected] > Sent: Wednesday, August 20, 2008 10:54 AM > Subject: RE: [Repeater-Builder] De-Sense and Circulator Question > > Yes, the de-sense is present when transmitting into a dummy load and when > transmitting into the antenna. > > > > -----Original Message----- > From: [email protected] > [mailto:[EMAIL PROTECTED] On Behalf Of DCFluX > Sent: Wednesday, August 20, 2008 1:06 PM > To: [email protected] > Subject: Re: [Repeater-Builder] De-Sense and Circulator Question > > > > <snip> > Also have you measured the desense into a dummy load? Does it only > appear when the antenna is attached? If so, Take a look at the FM > broadcast band and write down the stations you hear, then look for a > pair that is spaced 5 MHz apart. > > On Wed, Aug 20, 2008 at 8:49 AM, John Transue <[EMAIL PROTECTED]> wrote: >> The RG-214 is new. The cable was built by The RF Connection. I didn't >> see the shield, but RG-214 is supposed to have two silver-plated copper >> shields according to everything I have read. Has this been changed? >> >> At any rate, the problem of de-sense predated the installation of the >> new cable. >> >> John >> >>>-----Original Message----- >>>From: [email protected] [mailto:Repeater- >>>[EMAIL PROTECTED] On Behalf Of DCFluX >>>Sent: Wednesday, August 20, 2008 11:33 AM >>>To: [email protected] >>>Subject: Re: [Repeater-Builder] De-Sense and Circulator Question >>> >>>Is this new RG-214 that has the foil and braid? >>> >>>On Tue, Aug 19, 2008 at 5:15 PM, John Transue <[EMAIL PROTECTED]> >>>wrote: >>>> >>>> >>>> >>>> >>>> -----Original Message----- >>>> From: [email protected] >>>> [mailto:[EMAIL PROTECTED] On Behalf Of DCFluX >>>> Sent: Tuesday, August 19, 2008 4:13 PM >>>> To: [email protected] >>>> Subject: Re: [Repeater-Builder] De-Sense and Circulator Question >>>> >>>> >>>> >>>> Are you using LMR series or Belden 9913 for a feedline? >>>> >>>> >>>> >>>> No, I have RG-400 in the cabinet and RG-214 leading to the Heliax >>>feed line. >>>> >>>> On Tue, Aug 19, 2008 at 1:08 PM, John Transue <[EMAIL PROTECTED]> >>>wrote: >>>>> Members of Repeater Builder have been very helpful .<snip> Now I >>>am >>>>> wondering whether a circulator would provide additional isolation >>>and >>>>> further decrease the de-sense problem. Your advice would be much >>>>> appreciated. >>>>> >>>> >>>> >>>> __________ NOD32 3192 (20080616) Information __________ >>>> >>>> This message was checked by NOD32 antivirus system. >>>> http://www.eset.com >>>> >>>> >>> >>>------------------------------------ >>> >>> >>> >>>Yahoo! Groups Links >>> >>> >>> >>> >>>__________ NOD32 3192 (20080616) Information __________ >>> >>>This message was checked by NOD32 antivirus system. >>>http://www.eset.com >> >> >> >> ------------------------------------ >> >> >> >> Yahoo! Groups Links >> >> >> >> > > __________ NOD32 3192 (20080616) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.eset.com > >
