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:

http://techlib.com/electronics/aircraft.htm

 

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. 

Doggerland

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

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

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 ?

tinySA

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

PI4VPO

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

Antennas @ PI4VPO;

144.177 MHz

Lots of FT-8 signals today on 144.177 MHz.

Confirmation of one of the many QSO's today:

PA6GST

 Nice eQSL card from PA6GST received today:

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.