Aren't the whips just E-field sensitive? That is why they are noisy.
I'm not sure a better FET can get around a fundamental problem like
that.
wrote:
wrote:
The Burhans papers are on vertical whips. They are really noisy for HF.
But the list of papers is impressive.
++++++++++++++++++++++++++++++
Properly designed (and constructed) active antennas with a small (3'
or less) vertical
element can work very well. And in the right location will give a good
100' wire antenna
stiff competition. The trick is getting active devices good enough to
give acceptable
IMD performance. The JFETs Burhans are amazing and are still amoung the
best
easy to get devices avaliable.

I like the AmRad LF antenna as it still has enough gain to be very
usefull up to above
10M. The North Country Radio Active antenna is a lot chepaer and comes
as a nearly complete kit.
For construction details see:
http://www.northcountryradio.com/Published/actant_0896/page1.htm
For the ~45$ it represents a pretty good deal for anyone who needs an
active antenna.

Yodar in the shortwave antenna group mentioned they have changed the
FET and it
appears to be more resitant to IM.

Whatever you do avoid the McKay Dymek 100D! The 100E is now being sold,
but the
100D I tested was less then usefull. It belonged to a friend and was
NIB, but had set
around for a few years. The 100E could be decent or even great, but I
would as soon
as use a 50 Ohm dummy load as use the 100D.

Terry