pa0nhc 0,03-30MHz active
wide band (DX) receiving antenna.
New PCBs will become available.
On special order, i can build fully equipped and tested PCBs for you. Without housing nor external power supply.
- 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
- Broadband R/C coupling to the receiver, no transformer, adjustable output impedance.
With advises for cheap and effective de-noising ferrites
You need a clean, 13.6V / 150mA external power supply, fused at 0.2A.
A design for a little, noise- and rattle free power supply, is here.
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.
As the MINIWHIP is vertically polarized, it is NOT suited for reception of NVIS signals.
It is well suited for wideband reception LW/MW and short wave DX signals up to 30MHz.
New antenna unit.
|For your own safety, place a 0.2A fuse in series with the +12V
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:
Be sure you are protected by :
TIP : useable and cheap ferrite rings:
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.