Topband: (HWF) Horizontal Waller Flag ; one year report,

[Lee K7TJR]

Jose Carlos says.
     No preamps
RX open, no antenna                  - 124 dBm
50 ohms load                             - 124 dBm
RX plus 3 Norton preamps          
RX + 2 Norton, no antenna          -119 dBm
50 ohms load                             -115 dBm
HWF connected                         -113 dBm
VWF connected                         -110 dBm
 
When you connect the HWF using preamps with 33dB gain, the increase of back
ground noise over no antenna is 6 db, but it is only 2 db above the 50 ohm
load. When the HWF is working properly there is almost no increase on the
background noise when you connect the antenna at the preamp input. For a
dual flag HWF if the noise increase > 10 db or more something is wrong, if
its increase > 20 db mean one loop is open or very big common node noise
problems 
It is important to notice the kind of noise, the HWF noise is normally band
noise, QRN at the distance, but it is no thermo noise limited at my place. 


Lee says.
     First, congratulations on your research into such a fascinating 
antenna. Your data with the Norton amps leaves me with a question
as I am considering building a Norton amp.  You show that your receiver
with 2 Norton amps and no antenna (high impedance) has a -119dBm
 noise floor. You show that this raises to -115 dBm with a 50 ohm load.
 Your data shows an increase in noise with a low 50 ohm input
 resistance on the Norton.
      Have you made any tests to know the noise floor with a lower input
 resistance or possible +-J reactance at the preamp input. Or alternately
 do you know precisely the R+-J impedance of your feedline coming
 from your antenna right at the preamp connection? I have not found any
published data on the source impedance affect on noise figure of the
 Norton amps.
Lee   K7TJR   OR