[SBE] 950 STL curious problem

[Bob Reite]

Sounds like some sort of interference to me.  Hook a spectrum analyzer 
to the receive antenna and see if anything weird pops up.

A9xw at cs.com wrote:

> 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

> 

> 

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