Re: [Repeater-Builder] Repeater Interference

24 Nov 2004 01:38:44 -0000

 First off  You changed the Duplexer?
how about the cables?
I have found that a bad connection or Oxidation acts as a diode. and will allow the AM stations Audio to be heard.. I have this problem with a telco Box the Phone company placed
 Exactly 1/4 wavelength away From My 10 kw AM trnamitter.. Everyone in the Neighborhood hears my radio station on their Phones.. But its Not my problem... Its some Engineers problem  at thePhone Company. How stupid can One Be.. I know the answer  He has an Engineering degree In theory It should  Be ok where it s... NOT...

Mark Holman wrote:
I would get in touch with the station Engineer and ask him or her if they 
may adjusted something, added or removed anything within the past time frame 
that this interference started.  If they say No then you may have something 
on your end just went out.

I would start with the Ground to see if the continuity of Resistance is Zero 
Ohms. from Chasis, Cabinet, rack, etc..  especially green crud from moisture 
will start a resistance path to ground.

a good oscilloscope check will indicate intermittent, as well a VOM check.

Good Hunting !

Mark Holman, CRO
AB8RU
----- Original Message ----- 
From: "Jeff Thomas" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, November 23, 2004 6:25 PM
Subject: Re: [Repeater-Builder] Repeater Interference


  
Thanks Mike,

The station is 1420 AM.

Nothing else was changed besides the duplexer.

The AM station audio is audible during the entire time the repeater
transmitter is transmitting, even during the hang time.

It is a much lower level compared to the repeated audio and it is 
perfectly
clear. I could hear everything Rush Limbaugh was saying.

Thanks for your help.
Jeff - W2JRT


----- Original Message ----- 
From: "Mike WA6ILQ" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, November 23, 2004 1:29 PM
Subject: Re: [Repeater-Builder] Repeater Interference


    
At 07:43 AM 11/23/04, you wrote:

      
I have a 70cm repeater that is located about .75 mile from a commercial
radio station.

I was using a Cellwave Notch type mobile duplexer and experienced no
problems what so ever. Recently I purchased a new Sinclair Bp/Br Q318GR, 
4
cavity duplexer and replaced the Cellwave. This morning I have noticed
that
the nearby radio station is now coming through on the repeaters
transmitted
signal.

Anyone have an idea what causes this and how to get rid of it?

Thanks,
Jeff
        
Is the station AM or FM ???

What else was changed besides swapping out the duplexer?

Is the station audio audible during the received signal only, or is it
also there during the carrier delay ?? (the time period that the TX is
still up after the RX squelch closes and before the repeater carrier
drops).

Can you hear it under the ID?

How loud is it compared to user audio or ID audio?

Mike WA6ILQ






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