30M 250 uWatts

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AA1A
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Joined: 2009/01/26 - 22:37
30M 250 uWatts

I have been trying to find the power floor on 30M where decodes stop, and it seems to be around 15 uWatts or so for the conditions of the past few days...

The last 24 hours were spent with AA1A WSPR beacon @ 250 uWatts output and here are the following results:

139 connects exclusively with stations N3TFM, W9HLY, N9SZ, and W7PP, at distances from 559 to 763 miles...
Decode signal strengths varied from a threshold of -30db to -15 suggesting that a power level of about 10 uWatts at these times possibly could have caused a decode...

The best case was:
2009-11-04 21:28 AA1A 10.140133 -15 0 FN42pb +0 0.001 W9HLY EN70mt 1195 743

Starting now, 11-05-09 @ 1210Z the power out is 100 uWatts into the antenna...

The lashup for measuring power here is to set the IC-718 TX at 1 or 10 watts with a Bird meter, then insert a Weinshel coax. ( -20db @ 50W ) attenuator into a HP 1db per step attenuator to select power to antenna... ie: 1 Watt from TX -36db of attenuation = 250 uWatts delivered... This is confirmed on a SDR-IQ receiver which is checked against a HP RF signal generator ...
Attenuators were checked using S21 parameters on Agilent VNA so I am confident that power delivered is within a DB...

TNX for your being there...

Nightly copy from EU is now common place on the experimental 600M band with some decodes running into the +db signal strength range...
2009-11-03 23:12 SM6BHZ 0.503925 +5 0 JO57wq +30 1.000 AA1A FN42pb 5768 3584
Antenna is 600' vertical loop and 900' BOG ( Beverage on ground ) phased towards the NE...

73s from Dave @ AA1A - WD2XSH/17