[SBE] 950 STL curious problem

[Michael D. Brown]

First thing to do is determine which end the problem is...
--use splitter and run another receiver and spectrum analyzer, at receive
end
--put inline wattmeter at xmtr end
--check for splayed female N connector 

        |X|-c
        |X|-c      
        |X|
       /   \     
Michael D. Brown
President/Owner/Senior Engineer
Brown Broadcast Services, Inc.
3740 SW Comus St.
Portland OR 97219-7418 USA
503-245-6065 OFFC 
503-245-5773 FAX 
503-703-3202 CELL 
503-299-5740 PAGE EMERGENCY ONLY
mike at brownbroadcast dot com
www.brownbroadcast.com 

This email may contain confidential and proprietary material.  All rights
are reserved.  Do not forward or disclose any confidential material to third
parties without our permission.  All attachments have been scanned for
viruses prior to sending.

 


  _____  

From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of
A9xw at cs.com
Sent: Monday, July 20, 2009 8:54 AM
To: sbe at sbe.org
Subject: [SBE] 950 STL curious problem


Follow with me, this is wierd.   

Day 1,  14 mile STL path for radio, Moseley Starlink 9003Q with LanLink. 
Signal level  - 77.   Less than expected. Turns out trees in middle of path.


Waise receive antenna 50 feet and signal level improves to -73. All nice and
stable. 

2 months later, suddenly signal level drops to -80.  Check coax, (1/2"
Heliax)  couple of bumps.  By pass LanLink box at TX end, gain 2 db.  Bypass
LanLink box at RX  end gain 5 dB.  Back to -73.   

Receive level unstable, jumps from -73 to - 93 and back every few seconds.


All connections checked, and rechecked.  RX does not work at -93 (below
threshold). Patch in Comprex line.   

Replace 1/2" line with 7/8" line. No improvement in signal level.  -80 with
Lan link in, -78 with TX lanlink out, -73 with TX anbd RX Lanlink out and
signal begins jumping again -73, -93. 

OK, Lanlink serves as bandpass filter but only other signals on site are 2
class A FM's. 

Can't find cause of  -73, -93 signal level jumps ( a couple seconds between
levels and fairly regular). No improvement in signal level with increase in
coax, that should have gained about 2 dB since 1/2" had 4 dB of loss)
(260'). 

Antennas check good. (Scala grid type) 

Only other signal is 950 STL at 90 degrees and distant channel.  Rotating
antenna shows typical and smooth lobes and is dead on.   

Called Moseley, tech says he would bet his house it is not receiver. 

Any guesses other than LGM?  Nothing within 2.5 miles of RX site,  path is
clear and not near intersecting anything else. 

Henry 



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://seven.pairlist.net/pipermail/sbe/attachments/20090720/aa72d9a6/attachment.html>