HF-Index of pa0nhc technical HAM pages.
Since 20150113 this site is located at: http://www.pa0nhc.nl/ 

pa0nhc PCB service : Available PCBs

© The use, copy and modification of all info on this site is only permitted for non-commercial purposes,
and thereby explicitly mentioning my radio amateur call sign "PA0NHC" as the original writer / designer / photographer / publisher.

EN = Read this article in English language           NL = Lees dit artiekel in de Nederlandse taal.



NanoVNA modificatie.
pa0nhc 20100114



Antenna unit

Splitter unit.

Small, active wideband receiving loop antenna 15 kHz - 30 MHz.
(200 kHz - 30 MHz +/- 3 dB, good reception of VLF).

22 minutes video presentation on Youtube:


LATEST very successful developments :
- Fully balanced system from loop, coax, upto output transformer.
Floating COAX connection between antenna and splitter.
Common mode cable chokes, avoiding common mode noise coupling into antenna and splitter.
Screening housings, avoiding PIN1 problems.
Screened balanced loop, avoiding PIN1 problem.

Antenna unit need not to be grounded => easy installation.
Pure magnetic H-field antenna, only receiving with its loop, NOT with the feeder.
Screened loop, 2m to 3m circumference, connected with waterproof N-connectors.
N- buses installed in contact with the outside of the housing.

Broadband amplifier, carefully balanced, high-IP, high gain, flat response, in metal housing.
Input Low Pass Filter : .50 dB suppression of FM broadcast and VHF.
Low system noise floor, equivalent to -120 dBm (< S2) @ 20 MHz
(with software gain adjusted for signal output comparable with a dipole antenna).

This sturdy amplifier withstands :
- Lightning strike at 100m distance.
- More than 1 kW radiated at 10m distance.
S9+110dB dipole equivalent signal strength without blocking.

Splitter :
50 Ohms asymmetrical signal output,
filtered and fused 12 Vdc power input,
BNC buses installed in contact with the outside of the housing.

These spectra prove in a very noisy location an impressive common mode suppression !
0.02V/m field strength gives 0dBm signal strength indication. -73dBfs = S9.

SDRconsole, 80m. Difference up to 67dB (2000x). No signals with power off.

SDR#, VLF. Difference at 23kHz is 54dB (500x). Common mode signals are of no influence when power is on.



Mantelstroom smoorspoelen.
Elke HF amateur zou dit moeten weten.
Snap het, maak het.
Nieuw :
De invloed van tempatuur variaties op mantelstroom smoorspoelen.

Common mode chokes.

Some secrets of Common Mode Chokes revealed.
Every HAM should know this.
Understand it, make them.

New :
The influence of temperature changes in Common Mode Chokes.


Symmetrical DIPOLE antenna

with the coax feeder at one end.

UPDATED choke design.

Proven performance.


Impossible ?
Another "wonder antenna" ?
Check it out !

=>> This is NOT an "End fed antenna" ! <=
No TVI nor BCI !
Low received noise level.

© "pa0nhc Cobra" antenna  (1.8-14 MHz).
A horizontally running coaxial dipole.

No transformer, just one well constructed common mode ferrite choke.

         This could be THE solution if you :
-  Want a symmetrical radiating antenna, symmetrically powered into its center
-  But you cannot connect a feeder to the center of it.

Minimal induced RF in mains wiring, speaker cables, telephone line etc.
Minimal received RF from mains wiring, speaker cables, telephone line etc.

Matches to 50 Ohms on the 1/2 wave resonant (80m) band (making strong NVIS signals).
Needs an a-symmetrical tuner on other lower/higher bands.



          Wide spread FAKE-information :  
"The RF current around the circumference of a 1/4 lambda loop has a CONSTANT value"
!! WRONG !!

    True : 
Very thick oxygen-free copper tube plus silver soldering are not always better.  
For a larger than 1/10 lambda circumference loop it is ONLY MORE EXPENSIVE.
Read here why.

PRESENTATIE mogelijkheid in de Nederlandse taal.

Pure magnetic and balanced high efficiency  3-band transmit / receive loop antenna ©.
No TVI nor BCI.

24 minutes video presentation on Youtube :
27 min.
24 min.

Good performing outdoor loop, constructed with cheap tin-soldered 35 / 28 / 22 mm copper water pipe.

Simple remote tuning and band switching mechanism.

Optimal cost / performance ratio.

Small size with good efficiency :
16x smaller than a full size 80m dipole.
Only 2.5m x 2.5m square.

Optimal 1/4 lambda circumference for 7.1  MHz,
              1/8 lambda circumference for 3.65MHz.

Three-band operation : 

NO antenna matcher needed. 
Just tune the loop for best VSWR => GO.
Full 40m and 80m bands : VSWR = 1 : 1.0
60m band : VSWR =< 1 : 1.5.

One carefully developed ring core transformer circuit.

NEW matching transformer.
Better performance.



Lineaire voedingen ontstoren.

De-noising a linear power supplies.




Blokkeer lichtnet storingen voordat ze uw radio kamer bereiken.
Block mains power related noises before they enter your radio room.
















Page update 20181217 / 20200204
The famous Miniwhip (pa0nhc improved version). Active E-field wideband DX receiving antenna.
Again improved version © : 
Higher input impedance and widened VLF frequency range output. 
Better comon mode choke.

Youtube video presentation :
18 min.
18 min.

   PCB set
Flat and wide sensitivity range : < 10 kHz / >150 MHz +0/-3dB.
Vertically polarized non-directional reception of VLF, MW, SW, FM broadcast and 2m amateur bands.
AC coupled and optimally adjusted full class A circuitry.
Fused, over-voltage and short circuit protected combiner.
Over voltage protected antenna input circuit, max input 7.6 Vpp !! 
Max. output over 50 Ohms load : 1 Vrms (2.8Vpp / S9+85dB) !!
>> No IMD, clean reception <<

NEW instructions for optimal de-noising of coax feeder and splitter.


Developed by pa0nhc. ©

Tune able, very selective, narrow band
Active MAGNETIC (NVIS) receiving antenna.

PCB set is available

- The directive pattern is like a full size dipole @ 1/4 lambda height.
- If installed rotate able : 
Weakens horizontally and vertically polarized low incidence interference.

- From 1.8MHz to 7.2 MHz good (high angle) NVIS antenna .
- Very small size, smaller and more signal than a small loop antenna.
- Using standard available components.
- Internal noise free filtered power supply.
- Adaptable to frequency bands between VLF and 21 MHz.    
- Adjustable tuning-"span". (Prototype 3.65 MHz +-150 kHz).

Very good sensitivity and selectivity due to
     Hi-Q ferrite antenna followed by a Hi-Z FET buffer.

- Acts like a very good pre-selector.
- Tuning by back-to-back varicaps and special pa0nhc electronics,
   resulting in very good strong signal handling.

© pa0nhc development :
One thin coax line
transports all signals :

. The DC power towards the antenna unit,
2. The DC tuning voltage towards the antenna unit,
3. The received RF signal back towards the tuner unit.

Antenna unit housed in 60mm rain tube.
12.5x100mm Ui=125 ferrite rod in 32mm PVC tube.

Tuner unit with build-in power supply.
Clean, filtered and fused.


Radically new designed :
Top quality 80m ARDF direction finding receiver
© .
See also the 2m version.
PCB is available.

Single super,10.7MHz IF.
high-Q BALANCED ferrite antenna.
BALANCED Jfet buffer stage.

Very sensitive.
Gain adjustment range >= 90 dB.
Very positive sense action.
Pwr : 16-26 mA @ 9V-6V.
Cheap light weight ABS housing.
Small and light (305 g).
Commonly available modern components.
Only 4 SMD components.
Ready wound Neosid, or self wound coils.

Last update : 20180130

All info in easy printable PDF files.

Two versions with different sense antenna's.

  The left hand version above uses a 17cm rubber whip as sense antenna.
The right hand version uses a piece of ALU pipe on top as sense antenna. 


Finding radio-noise-sources using a specialized VLF - VHF wideband AM noise sniffer.

Radio stoor bronnen vinden met de EMVspion..


Rugged 2 Watts CW / AM transmitter for "80m radiofox hunt"
and 3.579545 MHz ARDF

2W CW into 50 Ohms load.
and AM when externally modulated.
Withstands very high SWR.
Fixed accurate carrier frequency without any adjustments.

Unconditionaly stable and sturdy.

Special designed single sided PCB for good performance and good efficiency.
Resulting in a well filtered signal, no parasitics,
Quick setup in the field without further adjustments, 
when using a 50 Ohms antenna


New PCB design 20180220  73.4x49 mm with separated ground planes for low harmonic levels.
This PCB can be supplied on special request.

80m FoxOring milliwatt AM-TX ©
(3.579545 MHz). 

9 different selectable tone modulations.

Buil-in antenna tuner with LED indicator for Hi-Z short-wire or short whip.

Power consumption 6-9Vdc / 40mA.

Max. 300m range using 1m ground wire and 1m antenna wire.


80m milliwatt beeper (Sputnik) ©.


Single frequency, simple, stable, clean signal.
CW keyed.
Well filtered, 50 Ohms. 
No adjustments.



Magnetic RF Field Sniffer.
pa0nhc 20190228 / EN : 20190726


Calibrate your S-meter ! 20180713.
Accurate calibration-free 50 Ohms 0dBm generator (3.579,545 MHz).
7 PCB set including neat lacquered housing.


Calibrate your S-meter !
50 Ohm 1dB-step  0-75dB attenuator.
for Hammond 1590S housing and cheap
toggle switches.

Under reconstruction.


Calibrate your S-meter !
50 Ohm fixed 73 dB attenuator.
7 PCB set
including 6 PCBs for constructing a neat painted housing.

Under reconstruction.


Simple manual "magloop" tuner ©.

Drives a 12Vdc capacitor tuning motor. Bi-directional, two speed.

Build-in clean power supply.
(New simplified schematic).


Article is under reconstruction.



Automatic "magloop" tuner.
3 PCB set.
Drives a 12Vdc tuning capacitor motor.
Pure analog (NO software).
Build-in clean power supply.

Tunes for zero phase difference between the RF current and the RF voltage in the transmission line.

Set of professional PCBs is available.


Youtube DEMO

Available PCB

TEXT UPDATE 20190905 : relay actions.

Xfilt : improved RF noise canceller for locally generated noises.

Including active noise antenna.
Build-in low noise power supply.

Safe and effective T/R switching
using external transceiver commands.

New professional main unit PCB with
build-in filtered PWRsupply.


RF and DC ouput
directional couplers
for in cheap metal enclosures.
28 - 435 MHz

Updated : 20180103\

Six different PCBs.


Low power 4mW RF rms meter © .
Internal 50 Ohms load.
Accurate, calibration-free.

Update 20191102 :
By Veron Lab measured properties at DVRA
in respect to 0.000 dBm source :
3.5 MHz -0.218 dBm.
100 kHz -2 dB
(lower generator freq. not available)
1.6 GHz -3 dB.

Measuring ranges :
32kHz up to 2.5GHz.
FSD = -14 and +6 dBm.
Indication range : -55 dBm to +6 dBm (3nW - 4mW)

(Battery) powered 4 - 5V, 3 - 8mA.
Cheap small standard ABS housing 9 x 9 x 6 cm3.
Available :
- Small double sided professional PCB in SHF design.
- dBm scale / switch scale drawings
- Full detailed info for building as easy printable PDF files 

pa0nhc  20171218



200W thru-line RF rms power meter © .
Accurate, calibration-free.

For external 50 ohms load.
16 kHz - 145 MHz.
3 ranges : FSD = 0.02 / 2 / 200W or -8 dBm to +53 dBm.
Indication range :
-8dBm - +53dBM (159uWrms - 200Wrms)
Optimal double sided VHF PCB design.
(Battery) powered 4 - 5V, 3 - 8mA.
Cheap small standard ABS housing 9 x 9 x 6 cm3.

Detailed info for building and dBm scale / switch panel scale in
easy printable PDF files
   pa0nhc 20171222

Without any adjustment, immediately correct +50 dBm indication
with 100W RF from a TS570D.


Tune your magnetic loop transmit antenna for maximal magnetic radiation.

Magnetic near field strength indicator © .
PCB set

Adaptable range : prototype 1.8MHz - 14 MHz.
With roof top sensor unit, and meter unit near the TRX.
Two sensitivity ranges.
(Battery) powered 4 - 5V, 3 - 8mA.
Cheap small standard ABS housings.
All detailed building info in easy printable PDF files.

Meter unit (L) and antenna unit (R).

NL Experiment : 600W PA met BLF188XR.
Het duurt zo lang omdat de financiŽn ontbreken..


The grounding and de-noising of my antenna system.
De aarding en ontstoring van mijn antenne installatie.



De-noising a commonly used scoot mobile charger.

Ontstoren van een algemeen gebruikte scootmobiel lader.



Ferriet transformator experimenten.

Ferrite transformer experiments.