Skipp, Interesting account! Will you be performing an autopsy to determine the exact cause of failure? I'm curious about how a bad cable on the TX side caused the RX to be degraded.
73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of skipp025 Sent: Thursday, December 28, 2006 9:25 AM To: [email protected] Subject: [Repeater-Builder] LMR-400 Cluser $*%& Again Re: LMR-400 Cluser $*%& Again Here we go again... date line Dec. 27, 2006 Trouble call to a high level repeater site yesterday... reports of a vhf Motorola Repeater not working well... very poor receive. Test the Receiver and Transmitter Sections for proper operation. Receiver checks pretty good... removed the un-needed problematic home brew (removed from a...) Motorola Motrac Mobile era receiver pre-amplifier filter assembly with a bad internal cable connection. Not the main problem source... just a future head ache. Some improvement in the receiver section... but not enough yet.... Those Motrac era receiver pre-selector amplifier assemblies are another topic/thread. Onward... Transmitter chain/side with matching tpl amplifier and Decibel IMD panel check out just fine. Put it all back on the Wacom Duplexer and the receiver sens "turns to butta'" (craps out). What are you thinking now..? Duplexer..? You would be wrong Mr Microphone. The Duplexer checks out 100% using various tests ... so what do we have left? Well bartender we figure one of the cables might be bad... let's see what we have here? Aaaaahhhh....! someone put an LMR-400 coax cable from the IMD panel to the duplexer. "Shoot that person!" Lucky for Mr LMR-400 man I don't know who he is... So out comes the LMR-400 (appears) factory made jumper and in we place a 1/2 inch andrew superflex hardline jumper. PROBLEM GOES AWAY..! The Repeater returns to normal operation... I finish my coffee (with cream) because the wind is doing 55mph plus outside. Within the last year I/we have had at least 3 episodes of LMR-400 feed-line causing serious trouble on repeater systems. At least two of those serious problems have started some x-value of time after the lmr-400 cable was first installed. **** LMR-400 is not allowed on Duplex Radio Systems within my control. In fact I try to get it out of antenna systems anytime I see it... I hope some of you don't fall for the low cost vs performance sales line... unless you have the time and resources to deal with un-needed trouble (self abuse). cheers, skipp
