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:
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 ?
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)
My first visit to VERON A42 clubstation PI4VPO in Hellevoetsluis / Voorne-Putten brought me a nice collection of (paper) QSL cards:
This afternoon some sporadic E clouds were present:
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:
https://en.wikipedia.org/wiki/Schottky_diode
Bunch of BAT85 Schottky diodes
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 ?
