HF-Index of pa0nhc technical HAM pages.

Since 20150113 this site is located at: http://www.pa0nhc.nl/ 
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.

pa0nhc PCB service : Available PCBs


EN = Read this article in English language     NL = Lees dit artikel in Nederlands

Mantelstromen smoorspoelen
(Common mode chokes).
pa0nhc / K9YC 

Snap het, maak het.

ON9BOG / PA0NHC  3.579,545 MHz 50 Ohms 0dBm generator.
Set of 7 PCBs, including 6 to construct a cheap but neat housing are available;
Check and calibrate your S-meter ! 20180713.
50 Ohm 1dB-step  0-75dB attenuator.
Single PCB (for Hammond 1590S housing).

Calibrate your S-meter !

Under reconstruction.

50 Ohm fixed 73 dB attenuator.
Set of 7 PCBs, including 6 PCBs for constructing a neat painted housing.
Calibrate your S-meter ! 20180712

Under reconstruction.


Simple manual magloop tuner.
Drives a 12Vdc tuning capacitor motor.
Bi-directional, two speed.
Build-in clean power supply.

(new schematic).

Under reconstruction.

Simplified schematic will be published.


Automatic "magloop" tuner.
The 3 PCB set is available.

Pure analog (NO software).
Detects phase difference between
RF current and RF voltage.
Drives a 12Vdc tuning capacitor motor.
Build-in clean power supply.
pa0nhc 20160321
Updated PCB designs.
Adapted for PRO pcb 20181209

Set of professional PCBs is available.


Tune able selective narrow band active MAGNETIC (NVIS) receiving antenna.
PCB set is available.

- if installed rotate able : 
   Suppresses local noise sources.
- The directive pattern is like a full size dipole.
- Much smaller size and more signal than a loop
- The tuning range is adaptable between
   VLF and 21 MHz. Prototype 3.5 - 3.8 MHz.
- The tuning-"span" is adjustable.
- Acts like a very good pre-selector.
- Good NVIS antenna between 1.8 and 7.2 MHz.
- Very good sensitivity and selectivity due to optimal
   Hi-Q ferrite antenna and Hi-Z FET buffer input.
- Very good strong signal handling due to tuning by
  back-to-back varicaps and special electronics. 
- Including internal noiseless power supply.
- Using standard available components.

    Special, developed by pa0nhc :
One thin coax line transports it all :

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 clean, filtered and fused, power supply.


Youtube DEMO

Xfilt : Onderdrukker voor lokale HF storingen. Aktief storing antennetje.
PCB is available.

Xfilt : RF noise canceller for locally generated noises.

Including active noise antenna.

Safe and effective T/R switching using external transceiver commands.
Build-in low noise power supply.

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


Six directional couplers
on a small piece of PCB,
in a cheap metal enclosure.
28 - 435 MHz

Updated : 20180103\

The six PCBs are available.

New design for coupler with DC output and RF output
on factory made double sided PCB.


Radically new designed :
Top quality 80m ARDF direction finding receiver, single super,10.7MHz IF.
PCB is available.

All info now in easy printable PDF files.

With build-in high-Q BALANCED ferrite antenna,
BALANCED Jfet buffer stage and

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

Last update : 20180130

See also the 2m version.

Two versions with different sense antenna's.

Finished receivers. 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. 

80m - 3.579545 MHz FoxOring / fox hunt TX.
PCB is available.

Nine different tone modulations.
Build-in Hi-Z short wire and whip antenna tuner with LED indicator.
Power consumption 9-6Vdc / 40mA.
With 1m ground wire and 1m antenna wire : abt. 300m range.



Active RF 4uW to 4mW rms low power meter.

The PCB is available.

-55 dBm to +6 dBm.
Internal 50 Ohms load.
32kHz - 800MHz (2.5Ghz).
2 ranges : FSD = -14 and +6 dBm.
Optimal double sided SHF PCB design.
(Battery) powered 4 - 5V, 3 - 8mA.
Standard ABS housing 9 x 9 x 6 cm3.
All detailed building info in easy printable PDF files for
dBm scale and switch scale drawings.
pa0nhc  20171218


Active 0.4mW - 200W thru-line RF rms power meter. Adjustment-free.
PCB is available.

For external 50 ohms load.
3 ranges : FSD = 0.02 / 2 / 200W or -8 dBm to +53 dBm.
dBm scale and switch panel drawings available.
16 kHz - 145 MHz.
(Battery) powered 4 - 5V , 3 - 8mA (30 hrs operation).
Standard cheap ABS housing 9 x 9 x 6 cm3.

All detailed building info in easy printable PDF files.

pa0nhc 20171222

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


Wide band Magnetic field strength indicator.
PCB set is available.

For "Magnetic loop transmit antennas".

Tune your magnetic loop antenna for maximal radiation.

With roof top sensor unit and meter unit near the TRX.
Two sensitivity ranges.
Battery operated.
All detailed building info in easy printable PDF files.

Meter (L) and antenna (R) units.



Easy and fast VSWR plots of antennas and filters on a laptop.
The PCB is available.

Complete with all software.
- cheaper BNC chassis bus
- 6 lead SOT-23 ic's for easier soldering
- 35mil holes for easier fit of both boards into the main board.
Makkelijk en snel VSWR grafieken van antennes en filters op een laptop.

Inclusief alle software.

- Goedkopere BNC behuizing bus
- makkelijker te solderen 6 pin SOT-23 ICs
- 35mil gaten voor makklijker plaatsen van de boards














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

The PCB set is available.

Higher input impedance and widened ultra low frequency range output.

Range : < 10 kHz / > 30 MHz.
Max. input for undistorted output : 7.6 Vpp.
Max. netto output @ 50 Ohms load : 1 Vrms (S9+85dB).
(Compare this with other versions).
AC coupled circuitry, Fully class A, 
>> No IMD, clean reception <<
Fused, over-voltage guarded splitter.
Over-voltage guarded input.


Simple noise free power supply .

For noise-critical applications (like the "Miniwhip").
PCB is available.

The PCB fits into a cheap standard 9x16 cm2 Hammond ABS box.   
230V~input, 12V/135mAdc output.
Last update PCB v15 : 20



WIDE SPREAD MIS-INFORMATION ==> In a 1/4 lambda circumference loop the RF current has a nearly CONSTANT value around its circumference <== !! WRONG !!

Pure magnetic transmit + receive loop antenna.

No TVI nor BCI.

Weather-resist, outdoor construction with remote
tuning and band switching.

Small size :
only 2.5m x 2.5m :square.

Three-band operation : 40m - 60m - 80m

NO tuner needed. Just tune the loop for SWR 1:1.0 => GO.

Always perfectly matched to 50 ohms coax, by one carefully developed ring core transformer matching circuit.   [(C) pa0nhc]

Loop constructed with cheap 35 / 28 / 22 mm copper water pipe.
Optimal cost / performance ratio.

Thick oxygen-free copper tube and silver soldering are not better

Read here why.


By pa0nhc developed

Low-Z matching.



Antenna SWRsweeper V1
re-editted 20170404

Easy and fast SWR plots of antennas and filters on a laptop.

SPECIAL :  Wide dynamic detector range by diode-compensated buffer stages 

Developed by pa0nhc.

SWR curve of my 10m circumference loop.
Sweeper connected at the transmitter end of the coax.



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.
box73.de "EMV-spy" with four different sondes.

Radio storing bronnen zoeken met een "EMV-spion". Vier verschillende sondes.
NL An ongoing experiment : 600W PA with BLF188XR.
It takes so long because lack of funds HIHI.


Symmetrical DIPOLE antenna
with the coax feeder at one end.

Proven performance.

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


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

The "pa0nhc Cobra" antenna (3.5-14MHz).
A horizontally running coaxial dipole.
No TVI nor BCI !
Low received noise level.
No transformer, just one dedicated coax choke.

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.

This could be THE solution if you :
-  want a symmetrical radiating antenna, but you 
-  cannot connect a feeder to the center of it.



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



De-noised 12V PC SMPS. 
Cheap 12.1V / 35A power supply for 100/200W transceivers.

Goedkope 12.1V / 35A voeding voor 100/200W zendontvangers .
Een ontstoorde 12V PC voeding.



De-noising a common used scoot mobile charger.

Ontstoren van een algemeen gebruikte scootmobiel lader.



Ferrite transformer experiments.


Rugged 2 Watts 80m CW or AM transmitter for ARDF.

The PCB is available.

2W CW into 50 Ohms load.
0.5W AM when externally modulated into 50 Ohms load.
Sturdy, withstands very high SWR.
Fixed accurate frequency without adjustments.
Unconditionaly stable and sturdy.

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



New PCB design 20180220  73.4x49 mm.


80m beeper.

The PCB is available.

(mini-TX "Sputnik").
Single frequency, simple, stable, clean signal.
CW keyed.
Well filtered, clean signal.
No adjustments.