During the years I have published articles and VHF-UHF-SHF columns in the monthly magazine CQ-PA from the VRZA (Vereniging van Radio Zend Amateurs). As writer from these article and columns I have the copyright and allowed the VRZA to publish them. There these articles and publications can be freely downloaded from my webpage. Please accept that some parts of the published pages are restricted in copyright as I am not the creator of those parts.

VHF-UHF-SHF columns in CQ-PA magazine

This frontcover of the January 2009 issue of CQ-PA shows a picture from LA/PA5DD during a 144 MHz meteorscatter DX-epedition.

Nearly 100 columns were writen. The following years are available:

Columns 2005: PDF-file; 5.873 kB
Columns 2006: PDF-file; 4.637 kB
Columns 2007: PDF-file; 11.434 kB
Columns 2008: PDF-file; 3.872 kB
Columns 2009: PDF-file; 5.487 kB

Other articles or presentations

Lecture given for the section NOL of the Belgian radioclub UBA. One of the members, Dirk ON5GS, was elected as best VHF DX-expedtion by users of MMMonVHF. Dutch language only. Slides with propagation theorie, maps and soundfiles from various propagation types.

Morsecode has always been my favourite mode. I learned it at a very young age so it was not too difficult. It took not too long before I could not go fast enough anymore on my Junker straight keyer so I builded this simple electronic keyer and a paddle. Almost hard to believe but even after 50 years it is still working. Most transceivers have keyers build in; my R2-CW did not so the old keyer was unboxed and build into the R2-CW. Simpel, straight forward an the used IC’s are still available. It does not contain an audio oscillator for the sidetone.

When using high power, preamplifiers, transverters and relays in your RX/TX-lines, you will need a sequencer to ensure that you are not hot-switching the relays. The article describes a 4-stage sequencer that will take care of that. Straight forward, easy to build with THT-components and (typical Dutch) much cheaper than commerciale available sequencers.

Receiving EME-signals should be easy as the strenght can be calculated when parameters are known from both the transmitting and receiving end. Signals that should be detected in theory, are in practice not so strong or even not there. The article explains terms like libration, scintillation, spatial offset, Faraday rotation and one-way propagation.

Nearly all commercial available antenna rotors have read-outs based on a voltage that is taken from a potentiometer coupled to it’s axis. Deviation can be up to 5% or 15 degrees. When an EME-antenna is 15 degrees off, you are out of business. In the search of a absolute read-out for a remote EME-antenna an experiment was done using a graycoded transparant disk and a reader to make an absolute BCD-encoder. It explains how encoders work and how this read-out was designed and build.

This article describes the build of a 144 MHz amplifier using the Russian GS35b valve. The amplifier is based on a design of DL4MEA. Output 2.5 kW

You should read Watts and not KiloWatts …

On June 5th 2007 a remarkable event took place on 144 MHz. At the same time it was possible to make contacts via forwardscatter (Sporadic E) and backscatter (FAI). This event was documented very well and therefore detailed analysing was possible. The following article from DF5AI (et al.) was published in CQ-PA. Software to visualise the event is BeamFinder which is used to analyse and predict Sporadic E and Aurora events. The website from DF5AI ( contains more interesting articles about propagation on VHF.