Hello Paul,

For your information, today I have tested a ´low noise vertical´.
This is a 50 mm diameter and 3.30 meter long aluminium pole.
The capacitance is 47 pf.

Using a transformer of 80 turns primary and 8 turns secondary on a high mu 
toroid the output 
as measured with a PERSEUS SDR on the carrier of a local NDB on 399.5 kHz  is 
-97 dBm. The 
output on my standard mini-whip mounted 4 meter high is -81 dBm. The output is 
low, but not 
completely useless, depending on the amount of local noise it picks up. At my 
location the 
signal to noise ratio is 10 dB worse as on my mini-whip antenna.

The K9AY is an excellent antenna and if you have the space, I should go for it.

I do prefer an omnidirectional antenna as at LF you never know the exact path 
of arrival.
I am not only interested in receiving amateur radio signals but also hunt 
NDB's, NAVTEX and 
DGPS stations. NDB's and DGPS stations from Canada are received here every day, 
Summer 
included.

73,
Roelof, pa0rdt