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pa0nhc 0,1-28MHz active wide band (DX) receiving antenna.
20170731

New version. Preliminary development data.

Sets new version PCBs will become available, and will be delivered including both transistors.
Price and delivering date not known yet.

You need a clean, 12.6V / 150mA external power supply. 
A design for a little, noise- and rattle free power supply, is
HERE 

This is a vertically polarized receiving antenna. Perfect for medium range and DX reception.
But (like all vertical antennas) it is NOT suited for NVIS reception (short range communication between 1.7 and 7.2 MHz)..

            Properties :
- New version 13, improved setting of T1, and commonly available new type UHF transistor for T2.
- Real class A circuitry, clean reception without IMD.
- Biggest strong signal handling.
- Maybe not the strongest signals, but the cleanest reception if well installed.
- Really wideband with R/C coupling to the receiver, no transformer, adjustable output impedance for critical cable lengths.
- One coax connection.
- Only commonly available parts.
- Only two SMD components with enlarged solder pads, easy soldering.

- With advises for cheap and effective de-noising ferrites

Klick HERE for the partslist.


Highly recommended to read :
Theory
about the practice of the Miniwhip antenna (written by pa3FWM).

Listen DX at :
The broad band websdr at the university Twente (50kHz to 30MHz).
They use my "Miniwhip".


 

Updated antenna unit circuit.

New schematic with improved setting of T1, and a commonly available modern UHF transistor for T2.
R13 is normally a wire bridge. Exchange it for 47 Ohm when T2 should oscillates with certain cable lengths.
Click HERE to download the antenna schematic.


This PCB must be installed vertically in a non-screening rain resist housing, for instance a
40mm PVC pipe 35cm long, closed with end caps.
The PCB  can be :
1. hanged on one screw through h1   or
2. Screwed at h1 and h3 with distance bushes   or
3. Hanging down from a PVC top end cap, by gluing the PCBs top end into that end cap.

The antenna surface "ANT" must be FULLY ABOVE the metal mast.
"GND h2" must be connected to the noise free grounded mast via a thck wire.

New splitter circuit.

Extra zener diode and fuse as protection.
Click HERE to download the splitter schematic.

 


New fused double sided PCB in a screening Hammond 1590a box.
With over voltage, shorted coax and wrong power polarity protection. 

Use two extra nuts for space between PCB and the bottom of the box.

 

Every antenna performs as good as its installation permits it to.

- For max. sensitivity :
    - this antenna should be positioned as high and free from metal conductors as possible
    - the ground plane of the PCB must NOT be lower than the top of the mast
        (the connecting trace between the electronics and the antenna surface, and the antenna surface itself must ALL be ABOVE the top of the mast).

- For best signal-to-noise ratio :
    - install the Miniwhip onto a well grounded mast
    - connect "GND" of the Miniwhip PCB (h2) to that mast
    - place HI-Ui ferrite cores (Ui between 3000 and 10.000) on the beginning and end of all cables, to block cable noise currents (see below).

For best noise free reception:

The complete Miniwhip antenna+splitter+power supply may only be grounded at the antenna pole.

Disconnect the ground wires at the receiver and the 13.6V power supply.

Be sure you are protected by :
an automatic ground-current-leak-switch in the mains supply line.

ALSO :
Before connecting plugs, install hi-Ui ferrite material on the beginning and the end of every cable.
Wind cables several times through the ferrite hole for far more effectiveness.
3 times through the hole = 9 times more effective than 1 time straight through the hole!

TIP : useable and cheap ferrite rings:
Conrad NR 534480
(Ui=10.000, remove the insulating shells).
Conrad NR 500683 (Ui=5000, Epcos B64290-L618-X35)
Epcos has more suited ferrite rings (ui=5000-10.000) in different dimensions.


(Earlier version antenna PCB).
Here a few windings through a HI-Ui ferrite core (Ui=5000 to 10,000) will block noises coming from the coax cable.
3 times through the hole = 9 times more effective than 1 time straight through the hole.
Use thin coax with maximal number of turns through the ring core.
==>> At h2, the ground plane of the PCB should be connected to a noise-free grounded mast.