Hello Lee Your antenna has gone bad---like somebody said---micro cracks.
What happens is that under transmitter excitation, there is micro arcing or more likely, rectification of the transmit signal due to the inevitable corrosion in the micro crack----the end result of either is wide band noise and the amplitude of the noise of course rises as the situation gets worse. In the early stages, the noise is often stimulated by wind caused flexure of the antenna. The wide band noise makes it's way down the feedline to your duplexer where your receive bandwidth of the noise is passed along with desired signals on to your receiver. The effect can be first noise crackles, then minor desense, and finally extreme desensing noise. The absolute test to verify this situation is to move a dummy load from a first test on the duplexer output and then a second test on the feedline in place of the antenna-----expect quiet normal operation both places----then, reconnect the antenna----noise confirms. Scott ----- Original Message ----- From: "Q" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, February 10, 2005 8:01 PM Subject: [Repeater-Builder] HELP! > > Been fighting with a severe interference problem for about a year,but > lately it has gotten so bad my repeater is totally unusable! > Heres the info; 147.870 input,147.270 output,GE MastrII base at 100 > watts,PLL exciter,UHS preamp disabled,Sinclair 202 duplexer,1/2 heliax > to a Diamond F23A,no reflected power at all.Also tried a 1/4 wave ground > plane,same results. All is fine until the repeater is keyed,I get > screeching-buzzing noises from hell.If I kill the transmitter,it goes > away. If I shift frequency of either the rx or tx,it goes away or at > least gets reduced. There is NO desense when tested on a dummy load. If > I tune around the 2meter band,I hear the same buzzing carriers at > multiple frequencies. Cant hear them when the repeater is transmitting. > Is this cruel intermod from some active device,ie-cable or sattelite > dish,ect...? Where/how to track this down? Ready to pull the plug and > sell it! Pulling what little hair is left,out! Any suggestions > welcomed...73,Lee,N3APP > > > > > > > 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/
