"Steven Swift" wrote in message
...
I have been following the antenna discussion and a lot of people
point to the low noise antenna web site
(http://www.anarc.org/naswa/badx/ante...e_antenna.html).

This site recommends a 9:1 impedance transformer. That matches
impedance, but you also lose 3:1 on your antenna voltage. I can put
a JFET in a box and get the same ratio, but without the voltage loss.
Other than the voltage needed, what would be the down side? The
power is so small, 4-AA batts will run it for a year, even if I
forget to flip the switch.

There are good JFETs that are a least as "flat" in response as the
transformer.

I always check the "prior-art" before I build something. But I will
be trying both this break.

TIA,

Steve.
Unless you very carefully select your JFET, you will experience intermod
and crossmod. In order to avoid this the devices used are those designed for
CATV applications where the IP3 is very high. This also requires a lot of
current to bias them properly.
For short active whips you might get by with something less, but for a
random wire, there is a lot of signal, and precautions need to be taken.
I would go with the 9:1 transformer- but wound on a binocular core not a
toroidal core- there is a near 10X increase in BW by doing so.
Dale W4OP