[Lowfer] Active Ants Redux

Tue, 15 Jul 2003 15:48:51 -0400

Bob, Bill, Eric & all

I've built and use three of the of AMRAD original e probes with the high
power CP666 FET. I experience no overload at this location with the strongest
signal being WTIC 1080 kHz at about 10mV/meter. There are many other signals
present that are 5 to 10 dB lower than that. The data sheet for the CP666
indicates a 1 dB compression level of +25 dBm and a 3rd order intercept of
+40 dBm. No second order IMD spec is given. The J-310s amplifiers I've built
for higher frequency applications have typical 1 dB compression of about 0
dBm and a third order intercept of +12 to +15dBm. This would indicate about a
20 dB advantage for the CP666 which seems about right with the amplifiers
I've built.

The preamplifier that I use on the big receiving loop has a 1 dB compression
of +22 dBm and a 3rd order intercept of about +35 dBm and does not suffer
from overload. A Burhans preamplifier connected to the same loop gets
completely blown away and is unusable. 20 dB of additional overload immunity
sure makes a big difference - at least at this location.

Jay Rusgrove, W1VD

[email protected] wrote:

> FYI
>
> I have the original probe in use. The specified device is ran at a high
> level
> Because the FET is designed to handle lots of signal it's response to
> strong
> local signals is excelent I am within LOS of several BC 5 Kw daytime
> stations.
> There is no problem from their signal.
> The original article in QST does have the performance data, as I recall.
> I unfortunately mounted it under the ambiguous shield that covers my
> property
> It is within 6 ft of my inverted 160 L .
>
> DUMMY   !!
>
> as Frank states "This shield needs to be
> punctured "    HAR    ( read the QST article )
>
> In any event it makes for a fine antenna at LF as well as the rest of the
> HF spectrum
>
> The J 310 version works well as a portable antenna and runs on 12 Volts
>
> Bob  K3DJC
>
> On Tue, 15 Jul 2003 11:58:36 -0500 "Peter Barick"
> <[email protected]> writes:
> >
> >
> > >>> [email protected] 07/15/03 11:42AM >>>
> > >Did the original articles address the performance of these
> > antennas
> > from
> > > a intermodulation resilience standpoint and actually put numbers
> > on
> > this
> > >performance?
> >
> > Hi, Bill, I don't. I have the source material in the car, I'll
> > check
> > into that and report back.
> >
> > > (This is the Engineer in me creeping through, again <G>)
> >
> > Of course.  :-)
> >
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> >
>
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