SS,

I look forward to Reading More about Your Idea and Design
for using a JFET Amplifier in lieu of a Balun for a "Low
Noise" SWL Antenna.

FWIW: If the 'stated object' of the Balun in a "Receive
ONLY" SWL Antenna is simply to Match the Impedance of the
Antenna to the Lead-In-Line.

NOTE: This type of Antenna does NOT require the Power Handling
Capabilities of a BALUN that can transform a few Watts to a Hundred
or more Watts of RF Power for Transmitting.

Then a JFET Amplifier placed 'between' the Antenna Element and
the Lead-In-Line could work as an Impedance Matching Device.

Plus the JFET Amplifier could provide an Additional Level of Signal
Amplification that a Balun could not.

But REMEMBER - The Balun as a "DEVICE" serves several purposes in
the "Low Noise" SWL Antenna Design and Configuration as presented
in writing by John Doty:
GoTo= http://www.anarc.org/naswa/badx/ante...e_antenna.html

* Impedance Matching between the Antenna Element and Lead-In-Line.

* Isolation of the Antenna Element and Lead-In-Line.

* A Remote (Low Noise) Grounding Point for the Antenna & Ground
System.

* Improved Antenna Lightening Protection and Electrical Safety.

You JFET in a Black Box would have to be able to accomplish these
same things to provide the same level of benefits that the Balun
does in the "Low Noise SWL Antenna Design and Configuration as
described by John Doty:
GoTo= http://www.anarc.org/naswa/badx/ante...e_antenna.html

* So First this JFET Amplifier would have to be "Located"
at the 'junction' of the Antenna Element and Lead-In-Line.

* Provide for Isolation of the Antenna Element and Lead-In-Line.

* Provide for a Remote (Low Noise) Grounding Point for the
Antenna & Ground System.

* Provide for Improved Antenna Lightening Protection and Electrical
Safety.


ABOUT - THE "LOW-NOISE" SWL ANTENNA:
When an OutSide/OutDoor is your First Option.
- But Before You Start:
- - Read about the "Low Noise" SWL Antenna
- - - created and written about by John Doty

* "LOW NOISE SWL ANTENNA"
http://groups.yahoo.com/group/SWL-AM...enna/message/2

* "LOW NOISE SWL ANTENNA"
http://groups.yahoo.com/group/SWL-AM...na/message/119

* "Two Reasons to use a Balun (Matching Transformer)
with a Receive Only Antenna"
http://groups.yahoo.com/group/SWL-AM...na/message/150

* "Understanding the Random Wire Antenna...
- - - And Building a Better One !"
http://groups.yahoo.com/group/SWL-AM...na/message/200

* "An OutSide Ground for Better Safety and more..."
http://groups.yahoo.com/group/SWL-AM...na/message/206

* "Am I Missing Something ? ? ? YES a Matching Transformer!!!"
http://groups.yahoo.com/group/SWL-AM...na/message/314


REMEMBER: The Antenna is 55.5% of the Radio/Receiver
and Antenna/Ground Reception Equation
http://groups.yahoo.com/group/SWL-AM...na/message/288


WHE "SWL Antennas and AM & FM Antennas" eGroup on YAHOO !
- When You NEED to Contemplate the
- - "Aerial High" and the
- - - "True Meaning of Ground".


iane ~ RHF
All are WELCOME at this "Antenna Ashram"
+ Who Seek Better Reception
+ + And a Clear Understanding
+ + + From That Which Transcends the Ether and Beyond.
..
..
= = = (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.

..