13cm receiver improvements

Completed DDK VLNA tuned up and on test.  Seems to have given me 2-3dB better S/N on the beacons. Should be even better when it is installed on top of the mast.

IMG_0455

Using the VLNA, I was monitoring GB3BSS but it wasn’t on its usual 2320.923925 MHz, it was sliding LF at an accelerating rate.  It then picked itself back up and started moving back to the nominal freqency, where is has been for 30 minutes or more.  Very solid tropo signal from the beacon at 240km over a very obstructed path

GB3BSS-TR-1605151830-drifting

 

The path to GB3BSS with earth curvature.  It says troposcatter loss is 208dB.

GB3BSS-path

GB3BSS runs 40 watts EIRP, so +46dBm eirp,  My antenna has 16.5dB gain, I have 2.4dB feeder loss and maybe about 0.3dB in the relays and internal coax at the moment.  That means I would expect to see 46+16.5-2.4-0.3-208 or around -148dBm.  Sensitivity of this end is at least 15dB better than that, but I have some local clutter problems which explains why I’m only seeing about +8dB above noise on average.  I think the preamp is working!

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