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Old December 1st 07, 12:14 AM posted to rec.radio.shortwave
RHF RHF is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 8,652
Default PA0RDT 'Micro' Active Antenna - What Is It ? -and- How To Install ItBetter !

On Nov 29, 4:10 am, wrote:
On Nov 28, 9:51 pm, N9NEO wrote:

I mentioned that I would post a comparison between Amrad and PA0RDT
and maybe loop too. I just want to say project has been delayed. I've
got Amrad mounted in a quiet corner of the lot with a good ground. I
ordered some nice coax today for the PA0RDT so I should be up and
running in a few days. From what (very limited) testing I've done so
far the Amrad does a nice job of pulling them in. I did hear the
local 1180am station way down the band so I will have to check that
out. Plenty of beacons and MW stations in there, but I wouldn't be
surprised if the MW loop outperforms in BC band. Overall I'm
impressed with the performance as it is good for everywhere I listen.
I used a 3 foot piece of 3/16" brazing rod with a 2' piece of 1/16"
brazing rod attached on top.


more later,
NEO


Visit the Kongsford web site and look at "The Dallas Files"
The Amrad was derived Dallas Lankffords works.
There are several udated variations that work much better then the
Amrad.

http://www.kongsfjord.no/dl/dl.htm

The dipole versions are nice because they can be rotated to null
noise,
or peak a signal.

If an active dipole dipole is mounted so the center can swivel and
allow the
antenna to rotate, you can rapidly check the effects of polarization
of a
signal. And see how the SN ratio changes.

For a derivative of the PA0RDT antenna that works very well
http://www.kongsfjord.no/dl/Antennas...0Complementary
%20Push-Pull%20Output%20Active%20Whip%20Antennas.pdf

I still have trouble accepting that a micro antenna acutely works!

Terry


Terry,

PA0RDT 'Micro' Active Antenna - What Is It ?
-and- How To Install It Better !

Some 'claim' that the Coax Cable used with the PA0RDT
'Micro' Active Antenna functions in a Dual-Mode with
the Active Antenna Element acting as a Far-End-Fed
Terminator for the Coax Cable {Antenna Element}.
* Mode-One 'Feed-in-Line' Receiver -out-to- End-of-Coax.
* Mode-Two 'Active-Antenna' End-of-Coax -back-to- Receiver

NOTE - If this is True then for the PA0RDT 'Micro'
Active Antenna to be more 'effective' it must be both
Remote-and-Isolated" as an Active Antenna Element.

1 - Remote Mounting Location for the PA0RDT 'Micro'
Active Antenna.
-Note- As Far from the House and Sources of Noise as
practicle and possible.

2 - Ground Rod and 1:1 Insolation {Coupling} Transfromer
at "The Base" of the Remote Mounting Location.
-Note- Power Injector is located here too; along with
DC Power to this location.

3 - Coax Cable 'Up-Line' from the Ground/Isolation
to the PA0RDT 'Micro' Active Antenna.
-Note- Free Standing 21 Foot piece of Top-Rail.

4 - Coax Cable feed-in-line from the Receiver to "The Base"
Ground/Isolation Point of the Remote Mounting Location.
-Note- Several Ferrite Beads along this piece of Coax
Cable and the DC Power Line.
+Plus+ 'Bury' the Coax Cable and DC Power Line -if- possible.

TIP - The Black PVC Half-Inch (1/2") Sprinkler Distribution
Tubing can be used as an 'Extra' Outer Cover for 'Buried'
Coax Cable that is placed along the Ground or only a 4"~6"
under the Ground. Use the Lawn Staples -if- the Tubing
is placed On-the-Ground.

plan before you build - iane ~ RHF