[Lf] probe

[Frank Gentges KØBRA]

Paul,

At 05:52 PM 1/1/01 -0500, you wrote:
>Hello Frank,
>
>I am very interested in the E-field probe you are working on.
>I wonder what the input device is that you are using in this design?

A Crystalonics CP666 JFET


>Is it still a very high input impedance, in the meg-ohm range?
>  The 3rd IP of +47 seems almost unattainable.

We are running the CP666 at 24 v and 65 ma.  It could qualify as a small 
transmitter.


>Even some of the best MMIC's are only in the low 30's

They don't have the heat sinking to allow the bias point to be cranked 
up.  If the LF radio amateurs  new to LF are to work against Loran C and AM 
broadcast stations, we needed to work hard to find a way to get it up 
there.  I had some help on key aspects from Dallas Lankford and he deserves 
a tip of the AMRAD hat for his contributions.


>Is there a diagram posted somewhere.

It will be in the AMRAD Newsletter article.  I have concentrated on using 
parts, skills and tools available to anyone.  In addition, I am working 
with FAR Circuits on making the PC boards available.  I include a power 
supply with low capacitance to the AC line and the receivers.  A 2 channel 
output is provided so you can run 2 receivers at a time.  Oh, by the way, 
it goes to 30 MHz so it is a decent SWL antenna.  I hope to develop a 
calibration factor for it to allow the ham to use a surplus selective 
voltmeter with the antenna to measure field strength in volts/meter but 
that is downstream.


>Thanks for your time Frank
>
>Paulc
>W1VLF
>
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>----- Original Message -----
>From: "Frank Gentges KØBRA" <fgentges at mindspring.com>
>To: "robert c riese" <riese-k3djc at juno.com>; <lf at amrad.org>
>Sent: Monday, January 01, 2001 16:26 PM
>Subject: Re: [Lf] probe
>
>
> >
> >
> > AMRADers,
> >
> > Indeed I am working on a construction project.  I hope to have a PC board
> > available and a set of instructions in our AMRAD newsletter soon.  Nags
> > Head will be the final acid test.  An earlier breadboard did pretty well
> > down there.  Hopefully the transition to the PC board will not degrade
> > it.  The PC board version tests pretty well in the lab so I am
> > hopeful.  The 3rd IP is a around +47 dBm.  I want to put it in the teeth
>of
> > the Carolina Beach Loran C transmitter.
> >
> > I have several kerosene heaters to keep warm.  We would like to see you
> > come down and participate Bob.  We have room in the cottage there.  It is
>a
> > chance to have some radio fun.
> >
> > Frank
> >
> > At 04:10 PM 1/1/01 -0500, robert c riese wrote:
> >
> >
> >
> > >We will try this year Franks' newly built e-field probe that
> > >appears to exhibit a fairly remarkable (+32dBm) compression
> > >point, and may thus go a long way to avoid the Loran signal
> > >interferences we experienced last year.
> > >
> > >lets hope there field trips result in some construction projects
> > >and no frost bites. stay warm.
> > >
> > >; }
> > >
> > >Bob  K3DJC
> > >
> > >_______________________________________________
> > >lf mailing list
> > >lf at amrad.org
> > >http://www.amrad.org/mailman/listinfo/lf
> >
> >
> > _______________________________________________
> > lf mailing list
> > lf at amrad.org
> > http://www.amrad.org/mailman/listinfo/lf
> >


Frank K0BRA