Experimenter hf net organizing

Frank Gentges fgentges at mindspring.com
Wed Aug 23 21:39:18 CDT 2006

Terry and all,

Terry Fox wrote:
> For a first step for receive-only stations, I could probably get an RX-320
> or PCR-1000 receiver running with an active antenna (Frank's e-field probe)
> fairly quickly.  I could use that for both our work here, plus the propnet -
> timehare the radio via the computer.
> Frank, maybe we should look at standardizing a receive package with an
> RX-320, active antenna (antenna tuning driven via computer and cheap A/D
> converter), plus some sort of cheap computer as we have been talking about.
> Would the LF active antenna up to 10 meters?  I don't remember the specs,
> and a lot of books, magazines, etc are still packed up somewhere (garage).

First, the RX-320 should do well at HF without the AMRAD LF 
modification.  Thus, use it right out of the box.

Second, the AMRAD Active antenna can be built with the J310 JFET instead 
of the high performance CP-666 JFET.  For most users that should do the 
job.  You can use the PC board kit and a J310 without the complexity of 
the heat sink.  For the HF use. a whip longer than the one meter would 
be a real help.  We would keep the PVC pipe fittings and use 12 volts DC 
for power.  The transformer could be the same or a substitute.  We were 
fighting interwinding capacitance to keep power line noise coupling down 
for LF use.  It is not so much a problem at HF and everything gets simpler.

Once I get some time (September perhaps?) I can build up a "standard 
package" for our HF work and write it up in the newsletter so everyone 
can duplicate it easily.  This is not that hard or time consuming.

Then everyone else can concentrate on the other parts of the problem and 

Perhaps a SoftRock receiver variant can be worked in here someplace down 
the line.

For a refresher on the antenna go to the AMRAD web page on it at


A link to the original article is provided along with many later notes 
on the construction.


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