[SBE] 950 STL curious problem
ebukont at msn.com
Mon Jul 20 12:28:23 EDT 2009
If Moseley told you its not the receiver, then check it again!!
Have you looked at the site with a spec analyzer?
Edwin Bukont CSRE, DRB, CBNT
V- 240.417.2475; F- 240.368.1265
From: A9xw at cs.com
Date: Mon, 20 Jul 2009 11:53:33 -0400
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.
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