Tuesday 14 December 2021


This is a screenshot of Meteor Scatter (MS) signals received yesterday:

Strong signals from S59A in JO21dq ! 

As you can see I used the MSK144 mode on 50.280 MHz. Ftol was set to 200.
I did not manage to make an MS QSO.


Nieuwendijk; ferry to Tiengemeten


Thursday 28 October 2021

Airband receiver

It is not difficult to receive nearby AM aircraft transmissions in the VHF airband (118 – 136 MHz). The aircraft transmissions use a bandwidth of 8.33 kHz. 

Dutch coastguard Do228

Since the ‘old fashioned’ modulation AM is used, a simple detector (e.g. Schottky diode) can demodulate the airband waves. The schematic below shows a simple receiver that enables you to receive (strong, nearby) AM transmissions. Not a lot selectivity, so you may receive more transmissions on various frequencies at the same time..


More info about this design:



I was intrigued by a similar design - using PNP transistors - a long time ago. It was a design from the book “Jongensradio” from 1967. I never built it. 

Sunday 26 September 2021


No, Doggerland is not a new DX entity. 

Doggerland was the land between England and Holland/Belgium/Denmark appr. 10,000 years ago. The Northsea has taken its place nowadays.

Doggerland, abt. 10,000 years ago

Past years the Northsea has shown to be a gigantic storage of fossils. Fossils from The Netherlands, with Doggerland as origin, can be found on the Dutch beaches, in particular Maasvlakte2 and the Zandmotor (near Kijkduin). The sand used for those beaches comes from the Northsea floor and contains fossils.
I have visited Maasvlakte2 a couple of times and have found some small bones of mammals from the Pleistocene.

Interesting to know is that the Northsea level rise was 5 - 10 cm a year those days. Past 100 years the Northsea level rise is appr. 1.5 mm (millimeter) a year.

I got in contact with Kommer Tanis, a fisherman who lives in Havenhoofd, close to where I live on Goeree-Overflakkee. Kommer is a fossilhunter and has been collecting fossils for the past 40 years. Between the fishes he catches, sometimes there are fossils. Kommer has a nice fossile collection at home. In his workshop he prepares the fossils.

The big bones are mammooth bones

Mainly horse bones / yaws

Mammooth yaw with 3 enormous teeth

Kommer has a small shop where he sells some of his fossils. The above picture shows part of a deer antler which I took home (Estimated 12,000 years old).

If you want to get in contact with Kommer Tanis, you can e-mail him: tanisfossils(at)go6tanis.nl

Saturday 11 September 2021

UHF amplifier under test

Last FT8 EU contest on 70 cm I participated with my homebrewed 50 Watt UHF amplifier. The amplifier uses an MRF186 in the final stage to boost the 5 Watt RF signal coming from the 28-432 MHz transverter. The amplifier seems to work well. I was able to make 25 QSO's during the evening (PA, ON, F, DL and G stations). Best DX was with Richard G7KHV in East Yorkshire (IO93vw) over 392 km.

FT8, 432 MHz signals

Amplifier under test

Housed in old Onkyo receiver case

Sunday 22 August 2021

LPF for 70 MHz

The RF output of my 28 - 70 MHz transverter shows an irritating 3rd harmonic at 210 MHz. 

I found a simple Low Pass Filter for 70 MHz at dutchrfshop.nl 

The filter should be able to handle RF powers up to 150 Watts.

4 ATC capacitors and 3 coils is all you need:

Arranged on a PCB as follows:

Some finetuning using the nanoVNA shifted the dip @ 70 MHz;

Next step is to test the LPF with the transverter..

Off-topic: Old QSL card

Crypto for radio gear

A couple of months ago I started to trade a bit crypto currency. The idea was to obtain some extra cash for the radiohobby.

I was intrigued by what was going on in the crypto currency community. Learned a lot about altcoins, bullish, bearish, blockchain, ECB, Elon Musk, whales, graphs, quantitative easing. With some trading of Bitcoin, Ethereum, ADA and  Dogecoin I have been able to gain some extra's to buy radio stuff.

What's your opinion on crypto currency ?

Sunday 11 July 2021


A spectrum analyser has always been a tool for me that I could not afford.I remember the expensive professional Hewlett Packard and Rohde&Schwarz analyser gear of which we radio hobbyists could only dream of.

The tinySA ('tiny Spectrum Analyser') has changed this.This nice, cheap, device enables you to visualize the radio frequency spectrum up till 960 MHz.

The tinySA has 4 main functions:

- frequency analyser till 350 MHz

- frequency analyser till 960 MHz

- signal generator till 350 MHz (sine wave)

- signal generator till 960 MHz (square wave)

tinySA with active signal in 70 MHz band

Span 60 - 80 MHz

Sunday 13 June 2021


My first visit to VERON A42 clubstation PI4VPO in Hellevoetsluis / Voorne-Putten brought me a nice collection of (paper) QSL cards:

Antennas @ PI4VPO;

Saturday 12 June 2021

144.177 MHz

Lots of FT-8 signals today on 144.177 MHz.

Confirmation of one of the many QSO's today:

Wednesday 19 May 2021

Friday 14 May 2021

QSO with 9A and GI on 70 MHz

This afternoon some sporadic E clouds were present:

A succesful FT-8 QSO on 70.154 MHz with 9A6R over more than 1300 km's.

In the evening strong signals from Ireland and Northern Ireland appeared:

QSO's with GI4SJQ, GI4SNA and EI2FG were made.

Wednesday 5 May 2021

Schottky diodes

A Schottky diode, also known as Schottky barrier diode or hot-carrier diode, is a semiconductor diode formed by the junction of a semiconductor with a metal. 

Typical metals used are molybdenum, platinum, chromium or tungsten, and certain silicides (e.g., palladium silicide and platinum silicide), whereas the semiconductor would typically be n-type silicon.

Schottky barrier diodes have a low forward voltage drop and a very fast switching action (typ. 5 ns).

A silicon p–n diode has a typical forward voltage of 600–700 mV, while the Schottky's forward voltage is 150–450 mV. This lower forward voltage requirement allows higher switching speeds and better system efficiency.

Lately I purchased a bunch of BAT85 Schottky barrier diodes. A typical value for its forward voltage is 200 mV.

I replaced four Ge diodes by BAT85 Schottky diodes in my field strength meter. http://pa2rf.blogspot.com/2020/07/fieldstrength-meter.html?m=1  . 

The performance of the meter has certainly increased (higher sensitivity).

More info:


Bunch of BAT85 Schottky diodes

Friday 12 March 2021


Bumped into my first ever bought computer. In 1981 (unbelievable, 40 years ago..) I bought this ZX81. Price at that time appr. 350 guilders. Learned BASIC programming with it. It was a splendid design from Sir Sinclair. Mind you, the computer had only 1 Kilo (!) Byte internal RAM. With an extension board on the backside (Memopak) an upgrade of 16 KB was possible :-). It contained a video modulator so you could use your (black/white) TV as a computer monitor. What was your first computer / PC ?

Tuesday 2 March 2021

Fauna in the garden

This non-radio related post is just to collect nice pictures from my garden. I hope to contribute a small bit to the (animal) biodiversity in my neighbourhood.

                                                            2 May 2022

2 March 2021

16 June 2021

2 March 2021

20 April 2021

9 May 2021

2 April 2021

12 April 2021

26 June 2017

12 March 2021

19 March 2021

30 March 2021

31 March 2021

2 April 2021

Thursday 4 February 2021

UHF Power Amplifier

This UHF final stage is waiting for a heatsink to arrive.

Off topic 13 February 2021

De Kwade Hoek, near Havenhoofd, Goeree

Monday 1 February 2021

North Sea Level rise

I have always had the idea, that past years the level of the North Sea has risen very rapidly. This is what the main stream media tries to make us aware of. Some meters rise coming years would be possible they say.

However, lately I bumped into this article:


I found that the last 100 years the North Sea level rise is lineair and does not show a grow acceleration. The absolute North Sea level rise is appr. 15 centimeters in a century (100 years).

This graph shows the average height of 6 sea costal stations in The Netherlands.

Deltares has published a nice graph showing the sea level trend.

In spite of this (only) 15 cm rise per century, I am not underestimating the forces of water and wind. I have a special interest in the sea level rise because I live on Goeree-Overflakkee. This island was struck by the ‘Watersnoodramp’ (North Sea flood) that took place in the night of 31 January/ 1 February 1953.

A combination of a high spring tide and a severe windstorm over the North Sea caused a storm tide. Dykes broke and the sea flooded up to about 6 meters above the mean sea level.

Today, this happened exactly 68 years ago. During this disaster 1836 people in Zeeland, Brabant and Zuid-Holland were killed. Also on the island where I live (Goeree-Overflakkee) more than 300 people lost their lives (Oude Tonge).

                                    Oude Tonge, 1 February 1953

Today, many people in the neighbourhood commemorate the flood and its victims.

Interesting story for radio amateurs: About 20 km from where I live, in Zierikzee (capital city of Schouwen Duiveland), Peter Hossfelt jr. –working in a radio store/shop - managed to make a 80 mtr band transmitter to inform the rest of Holland about the disaster that had taken place. A replica of this transmitter can nowadays be found in the ‘ Watersnoodmuseum’ in Ouwerkerk.

More: https://www.pa3esy.nl/zelfbouw/Watersnoodzender-1953/html/Watersnoodzender_set.html