TopBand: RE: loops and preamps

Tue, 7 Oct 1997 08:23:21 +0000

Hi Peter,

> Eric N7CL has a point. It all depends on how much or how little
> background noise there is. I use a 2 turn loop about 1 metre on a side,
> with a push pull cathode follower, and get more than enough noise - it's
> better than the vertical, but still not good enough!

How do you avoid unwanted common mode excitation of the push-pull 
follower? High input Z amps, especially those with ground referenced 
supply and signal leads (generally the case with tubes), require 
special precautions.

If you are talking about Brian Besley's QST antenna, it is a good 
system. But like all small balanced systems it requires very low 
common mode response in the transmission line / amplifier system.  
Otherwise, it would just act like a mess of wire random wire instead 
of the well designed antenna it really is.

73, Tom W8JI
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