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Pa0nhc 0,03-30MHz active broadband receiving antenna.
A vastly improved version of the pa0rdt "Miniwhip".
201702

For this project you canNOT anymore order the PCBs shown below.

You could use the "dad bug" method to solder both antenna and splitter on pieces blank PCB.

A design for a little, noise- an rattle free power supply, is here.


Splitter and antenna PCBs, ver.20160701.

    Properties :
- New version, using modern BF998 and a BD139 semi conductors
- Real class A circuitry, clean reception without IMD.
- One coax connection.

- Easy soldering :
    only one SMD part
    grounding connections have thermal relief lines
- Broadband R/C coupling to the receiver, no transformer

With advises for cheap and effective de-noising ferrites

You need a clean, 13.6V / 150mA external power supply, fused at 0.2A.

Parts list including ordering info (PDF)

Construction and installation instructions PDF


Do not use a Jfet for T1. Use a mosFet as T1 must have a low input capacitance and be able to draw a peak current of 40mA.
ZD1 protects against high supply voltages.
T2 is a NPN audio driver with high Ft value (BD135/137/139, Ft=190MHz).


h2 must be connected to the grounded mast by a short wire.
h1 can be used to hang the PCB on a 50mm long M3 screw which is drilled through the plastic pipe (see photo =>>)
The drain current of T1 should be adjusted by removing the bridge at R2a, and insert a resistor, until Ur4= 3.0V +-10%. 
The value of R2 depends on the transistor type used. Try R2a=1Mohm first.

MOSfet T1 is soldered on top.
A BF998 tetrode can be soldered with both gates to island "g1+g2".
If a BF999 triode is used, it must be positioned upside-down.
The connecting islands for T1 are big enough to solder older types dual gate MOSfets with legs.

NPN transistor
T2 (a hi-Ft audio driver transistor BD135/137/139) is cooled by screwing it onto the PCB.
(A high Ft value is important).

20160915.: If a BDxxx is hard to obtain :
you can try to use two or three paired 2n5550 in parallel. Buy ten pieces and find equals using an digital meter.


Miniwhip in a 25cm long, 50mm dia plastic pipe. With a yellow wire for grounding to the mast.


Splitter.

For your safety, place a 0.2A fuse in series with the +12V connection.


This new version double sided PCB is screwed inside a Hammond 1590a box.
Extra nuts between the PCB and the box act as spacers to prevent an unwanted short circuit to ground.
=> Please use the stated component types for L3,4,C7. <=

 

Each 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 connection to and the antenna surface itself must 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 to that mast
    - place HI-Ui ferrite cores (Ui bwtween 5000 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
and a 0.2A fuse in the +13,6Vdc supply line to the miniwhip.

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.


Here a few windings through a HI-Ui ferrite core (Ui=5000 to 10,000) block noises coming from the coax cable.
3 times through the hole = 9 times more effective than 1 time straight through the hole.
==>> The ground plane of the PCB should be connected to a noise-free grounded mast at hole h2.


Please read :
Theory
about the practice of the Miniwhip antenna (written by pa3FWM).

You can listen to :
The broad band websdr at the university Twente (50kHz to 30MHz).
They use a Miniwhip.