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.



Small active balanced receiving loop antenna : wideband 25 kHz - 36 MHz.
Constant sensitivity between 25 kHz and 15 MHz.
Pure magnetic, floating, loop not screened, amplifier not grounded.
Update : 20190806 12:00

PRESENTATIE mogelijkheid in Nederlanse  taal.

Loop :
15x2mm aluminum strip,
60cm diameter / 2m long.

Cross : 45 / 18 mm PVC pipe.

Amplifier housing :
75 mm PVC pipe.

Balanced amplifier.


Developed by pa0nhc.

Tune able, very selective, narrow band

Active MAGNETIC (NVIS) receiving antenna.

PCB set

- 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 power supply.
- Adaptable frequency band : VLF to 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.

    One thin coax line transports all signals :

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


Common mode chokes
(mantelstromen smoorspoelen)
K9YC pubications 

Info voor optimaal ferriet materiaal en optimale constructie.

Snap het, maak het.

mogelijkheid in Nederlandse taal.


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. 


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.
32kHz - 800MHz (up to 2.5Ghz).
2 ranges : FSD = -14 and +6 dBm.
Indication range :
-55 dBm to +6 dBm (3nW - 4mW)

Optimal double sided SHF PCB design.
(Battery) powered 4 - 5V, 3 - 8mA.
Cheap small standard ABS housing 9 x 9 x 6 cm3.

Detailed info for building
dBm scale / switch scale drawings
in 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 (L) and antenna (R) units.














The famous Miniwhip (pa0nhc improved version). Active E-field wideband DX receiving antenna.
          PCB set

LISTEN to a Brazilian LW / MW (100 kHz - 2 MHz) web-sdr using a pa0nhc Miniwhip antenna : http://sdritajai.ddns.net:8082/

Page update 20181217 
Again improved version : 
Higher input impedance and widened ultra low frequency range output. 
Better comon mode choke.

Flat and wide sensitivity range : <15 kHz to >30 MHz.
Max. input for undistorted output : 7.6 Vpp !!
Max. netto output over 50 Ohms load : 1 Vrms (S9+85dB) !!
AC coupled circuitry, fully class A.
>> No IMD, clean reception <<
Over-voltage guarded input.
Fused, over-voltage guarded combiner.



          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 Nederlandse taal.

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

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.
(C) pa0nhc.

NEW matching transformer.
Better performance.



Een goedkope manier om te voorkomen dat lichtnet storing uw radios bereikt.

Cheap prevention mains noises polluting your radio equipment.




Finding radio-noise-sources using a specialized VLF - VHF wideband AM noise sniffer.
"EMV-spy" with four different sondes.   

Radio storing bronnen zoeken met een "EMV-spion". Vier verschillende sondes.
NL Experiment : 600W PA with BLF188XR.
Het duurt zo lang omdat de financiŽn krap zijn.

Symmetrical DIPOLE antenna

with the coax feeder at one end.

This is NOT a conventional "End-fed" antenna.

Proven performance.


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

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

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

No transformer, just one dedicated common mode coax choke.
NEW improved choke construction.

         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 lowest band (making strong NVIS signals).
Needs an a-symmetrical tuner on the higher bands.



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.



Ferrite transformer experiments.