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.


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

See my Youtube video presentation  English 18 min.

Two PCB set will be supplied WITHOUT any component. (see PCB service).

==>> All components have to be purchased and placed by yourself.

Updated 20240303.




Mogen twee-draad-CMCs ook in coaxiale voedinglijnen gemonteerd worden ?    pa0nhc V20220524-21  PDF.

Can twin-line CMCs be inserted into coax feed lines ?
 pa0nhc V20220524-5  PDF.

EN Pure Signal Power Tap for HL2 Version 1.
EN Pure Signal Power Tap for HL2 Version 2. 20220226.
EN The Hermes Lite2 five Watt  high quality SDR TRX open source project. Update 20210331

Smoorspoelen (CMCs) en transformatoren
voor ontvang antenne circuits.
pa0nhc 20210121 


Praktijk informatie over CMCs.
Smoorspoelen (CMCs) voor zend antenne circuits.
Maak zelf de beste en goedkoopste CMCs.

Wilt us alle info over ferriten ? Download dan de Fairrite catalogus :

Deze catalogus bevat ALLE technische informatie over 19 soorten ferrieten, en in ALLE formaten.

pa0nhc UPDATE 20211008

High power CMC. Ferriet kosten slechts 50 Euro.



Mantelstroom smoorspoelen (CMCs).

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

Mijn information source :
Common mode chokes (CMCs).
A theory subset.
Some secrets of Common Mode Chokes revealed.
Every HAM should know this.
Understand them, make them.

New :
The influence of temperature changes in Common Mode Chokes.
pa0nhc 20211003

WebSDR muter. pa0nhc 20201105 
UPDATE version2 :  202105

Silences webSDR sound while you are transmitting.
No software, only simple hardware.
No latency.


Update : 20210505
Project : Shortwave RF power amplifier "QRPblog A600 PCB v 2.1". 
400W low IMD SSB with 1W drive. (see also Hermes Lite2).
After important modifications : now reliable.

20210414 : The new peak metering PCB is available.

EN HOW TO de-solder a (TO220) power transistor.


Loop impedance converter+amplifier.                 Signal / DC combiner                  Coax cable loop
Balanced screened input.
Balanced COAX output.

Loop                                                                           Loop

To splitter

Shielded antenna unit.

Balanced COAX input.
Unbalanced coax output.

        From antenna

         To receiver  12-14Vdc from PS

     Shielded DC/RF splitter unit.

Shielded loop

Connected by 20m 2.5mm PTFE coax
with every 3m a #31 CMC
The coax thus acts as a
screened  balanced line !

PCBs are available

Page update 20211009.
Small, active, wideband active receiving loop antenna 15 kHz - 30 MHz.
200 kHz - 30 MHz +/- 3 dB, good reception and superb noise immunity down to VLF.
Special :
The antenna unit is not grounded
=> easy installation and best noise immunity.
Superb common mode immunity guaranties magnetic-field-only / ANTENNA ONLY receiving and best noise immunity.
Also : Far weaker thunder storm lightning noises.
Very low system noise floor, equivalent to S1, or -120dBm.@ 20 MHz (IARU 6dB/Spoint).
This sturdy amplifier withstands :
- Lightning strike at 100m distance (proven).
- More than 1 kW radiated power at 10m distance.

This spectrum is recorded in my very noisy location, and demonstrates the impressive common mode suppression !

Measuring conditions :
SDRconsole software, recorded at my locally very noisy 80m band (S9+10dB noise).
Given facts : 
1. A 1/2 wave 50 Ohms dipole has, in an RF field of 0.02 V/m, 0 dBm output.
2. This loop system has, in an RF field of 0.02V/m, -30dBm output.
3. =>> No signals with power off means : no common mode noises <==
By in SDRconsole adding +30dB "software gain", the S-meter indication is automatically calibrated for -73 dBm (S9) for this loop system. 

The signal strength difference between power on and off is 50 dB to 70 dB over the full system bandwidth of 15 kHz - 30MHz.
The common mode suppression of this antenna system is that good, that one can only judge it, while observing very strong signals >-40dBm.

This remarkable performance is only achievable by applying all my :
1. De-noising measures, 
2. Construction details and advises,
3. Recommended common mode chokes installations.





De overeenkomsten en verschillen tussen een
Miniwhip E-veld antenne en de
pa0nhc RXloop H-veld antenne.
pa0nhc  20200708.

The similitudes and differences between a 
Miniwhip E-field antenna and my
pa0nhc RX loop H-field antenna.


This could be THE solution if :
-  You want a dipole antenna
-  But a feeder running towards the center is impractical.

The © "pa0nhc Cobra" antenna  (1.8-14 MHz).
A horizontally running coaxial dipole.
with the coax feeder at one end.
Proven performance.
Impossible ?
Check it out !

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

Pa0nhc "Cobra" antenna.
=>> This is NOT an "End fed antenna" ! <=

No TVI nor BCI !
received noise level.

Choke construction update : 20220401



Outdoor, all whether, high efficiency, balanced 3-band transmit/receive (magnetic) loop antenna.
Unique, wide band, pa0nhc © transformer matching.

Good performing loop. Cheap and simple construction.
Remote tuning and band switching mechanism.
Optimal cost / performance ratio.
No TVI nor BCI.
NO antenna matcher needed. Once tuned : perfect VSWR.

Small size :
Only 2.5m x 2.5m square.
3-band operation. : 40m,60m,80m
Optimal performance on 7.1  MHz.
Still good performance on 3.65 MHz.
Maximal allowable power on 80m : 400 Wssb
with a 2x 600pF 3kV split stator tuning capacitor :
Higher power levels need a higher voltage tuning capacitor
and a transformer made with two stacked ring cores.

Press F5 to get the updated page version.
Updated text and pictures : 20221204

Capacitor setup with NanoVNA / Partslist.


Developed by pa0nhc. ©opyright

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 :

1. 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. 



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.




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 63 dB attenuator.
7 PCB set
including 6 PCBs for constructing a neat painted housing.

Update 20200820.


Simple manual "magloop" tuner ©.

Drives a 12Vdc 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

Updates :
0190905 : relay actions.
20210216 : optimal antenna combinations

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.


MAGLOOP test equipment.
PA0NHC magnetic near-fieldstrength indicator © .

This tester enables you to veryfy that the "frequency of best VSWR" of your loop, exactly coincides with its "frequncy of max. radiated field strength".They should be, but are they? When the coupling between coax and loop  is perfectly balanced, no frequency difference occurs, and the loop efficiency is optimal. 
A possible difference can thus be caused by an non-balanced type of coupling.

The tester is useable for all shortwave bands.
The sensor unit is placed near the loop. The indicator unit is placed near the TRX. Both are interconnected by a 3 wire twisted cable.
The indicator  has two sensitivity ranges. It is powered 4 - 5V  (3x AA batery or a 5V mains blck), consuming only 3 to 8mA.
Both PCBs are mounted in cheap small, water tight ABS boxes.
All detailed building info is here available in easy printable A4 PDF files

Order the PCB set .

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.



NanoVNA modification.
pa0nhc 20100114