Sunday, 1 November 2015

MARS mod for FT-450

There is a way of extending the TX frequency range of the FT-450 transceiver. The so called “MARS” (“Military Affiliate Radio System”) modification provides out-of-the band operation of the transceiver. You can operate anywhere within the range 1.8-40 MHz after the transceiver has been modified.

The modification is simple. Just remove jumper JP4002 on the control pcb and make some settings. A description of the mod can be found here:

YouTube shows the instructions as well. For example this one for the FT-450D:

Example of out-of-band operation:

Jumper to be removed:

It took me some courage to open the transceiver and do the mod, but in fact it turned out to be rather simple.

Sunday, 18 October 2015

KT-8900 VHF/UHF transceiver

If you are looking for a small, low budget, VHF/UHF transceiver the KT-8900 from manufacturer QYT from China might be your choice.
For under $100 you are the owner of this FM mobile transceiver with a weight of only 400 grams.
It has a frequency range for VHF from 136 to 174MHz and for UHF from 400 to 480MHz.
Transmitter output power is 25W in the VHF range and 20W for UHF operation.

A picture of my view at the new QRL at Schiphol

Wednesday, 5 August 2015

Encounter with Aeronautical Mobile station

Yesterdag, August 5, I made a nice radio contact via the repeater PI3UTR (145.575 MHz). With my UV-5R porto I had a QSO with Gerrit, PA0GJC/AM, who was transmitting from a small piston engine driven aircraft. At the moment of our contact he flew above the Dutch coast near Noordwijk heading for Rotterdam-The Hague airport.
I hope Gerrit acknowledges the radio contact by eQSL.

Sunday, 26 July 2015

DIY frequency counter

There is no excuse anymore not to provide your receiver or transmitter with a frequency counter.
For 6 euro's I built a counter which measures frequencies from 1 Hz till 50 MHz.
I ordered the "Do It Yourself" kit here:

The counter can also be used as crystal tester.

The counter is designed around a PIC 16F628 that also contains a table with most used IF frequencies which you can add or substract from the measured frequency.

Very nice design with big LED displays !

Kit parts

Half way

                                 The counter works ! 16 MHz X-tal here under test

Close look with 4 MHz X-tal under test

Wednesday, 15 July 2015

Collector items

Yesterday I found a box with old components. Some of them were germanium transistors.
I must have kept those semiconductors since about 1977. I remember building a simple MG-radio receiver with an AC125. 
I am not good at throwing away things. Now these components have become real collector items.

Friday, 15 May 2015

60 m band

As a result of a request from VERON ("Vereniging voor Experimenteel Radio Onderzoek Nederland") to "Agentschap Telecom", in the Netherlands there is a chance that part of the 60 m band (5250 - 5450 kHz) comes available for experiments in the near future. This band, located between 40 and 80 m, is very interesting to do (QRP) experiments.
Although the operating frequency is below 10 MHz, the common voice mode used in the 5 MHz band is USB.

In advance of the release of the bandsegment I thought about a 5 MHz transverter. When using a 21 MHz transceiver, with a 16 MHz local oscillator, a transverter could look similar to the design shown below.

Friday, 8 May 2015

70 cm WebSDR

Since begin this month a UHF 70cm WebSDR has been activated.
The 70 cm antenna of the Software Defined Radio has been located in the
centre of the Netherlands, the Gerbrandytoren.
The frequency range of the receiver is 430.000 - 432.000 MHz
The URL to access the receiver via the internet is:


Sunday, 3 May 2015

Hybrid TV PCI Card

If you want to watch life TV on your PC you might install a DVB-T USB stick these days.
A couple of years ago, when those USB sticks were not available, there were computercards that did the job.
Last week at kingsday we went to a fleemarket and found an unused Hybrid TV tuner card from Zolid (manufacture date 2009).
In the box, apart from card and software, an antenna, remote control and IR-eye had been included.
This morning I installed the card in an old Pentium IV pc that runs with Windows XP.
After installation of hard- and software (driver and "Total Media") I now can watch "free-to-air" transmissions of DVB-T stations (NPO1, NPO2, NPO2 and a local station) and listen to some radiostations. Decoding of "Teletext" signals works fine.
Besides the reception of DVB-T transmissions there is an option to watch analogue signals. Although the max receive frequency is 864 MHz, this option might be interesting for further experiments. 

Components used on the TV card:
-TDA18271 (tuner)
-TDA10048 (demodulator)
-TDA8290 (analog IF demodulator)
-SAA7131E (A/V decoder/pci interface)

                                                  Zolid TV card

Zolid TV tuner card

                                                      TV card installed in PC (aft card)

                                                   "Total Media"  up and running

Tuesday, 28 April 2015

DIY LF oscilloscope

One of the most interesting Do It Yourself kits I saw recently is digital oscilloscope with a 2.4 inch color TFT display. The scope can show signals up to a frequency of around 200 kHz.
The price is amazing: 21 euroos...

All the ins and outs can be found via this link.

Another interesting gadget to identify your unspecified components:

Saturday, 18 April 2015

Holy Land contest

Today I made some QSO's with Israelian stations participating in the Holy Land Contest 2015.
Conditions on 10 meter were ok since in 20 minutes I worked following stations:
4Z67TL, 4Z5LA, 4Z5WC, 4X4JU and 4Z1UF.
I used 20 Watts in USB around 28.500 MHz

Friday, 17 April 2015

More Moore

Today I ran into an interesting visualization of Moores Law;
the amount of integrated transistors versus time.
Each 2 years the amount of transistors doubles. From the 4 bit 4004 processor from 1972 to the most sophisticated processor nowadays (Xeon, 15 core). 
50 years ago Gordon Moore was right:

This week I drove along an old railway station that is not used anymore as station. I could not resist making a nice picture.

Station Vogelenzang-Bennebroek - along railway line Leiden CS-Haarlem - was built in 1880 and used as railwaystation until 1944. 

Thursday, 9 April 2015

BC-696 transmitter

This week, at the radio club, a green radio, BC-696 was shown. This transmitter has been revised by Mans, PA2HGJ. He designed a Power Supply Unit for the valve transmitter so now it can be fed with 230 VAC mains.
The BC-696 had been used in Worldwar II in bomber aircraft like the B-17.
The transmitter originally uses 28 VDC power and was operated in CW or AM voice mode. It has two 1625 tubes in the Power Amplifier and is capable of delivering 50 Watts RF in the 80 m band ( unit operates from 3 - 4 MHz).

                               Frontview BC-696 CW/AM transmitter 

                                                Top view opened BC-696

Bottom view 

Side view

PSU, designed by PA2HGJ

Saturday, 28 March 2015

Confirmation 4m contact with Slovenia

Summer 2012 had some good moments for VHF sporadic E communication. I made an SSB 70 MHz contact with Joze, S51ZO June 10, 2012. This week I received the paper QSL:

The website of Joze:
Joze used a six elements antenna while I used an indoor dipole (!)

Slovenia has areas with a beautiful scenery

Saturday, 7 March 2015

ATV transmitter in "QRP Nieuwsbrief"

Today I received the newsletter "QRP Nieuwsbrief"  and saw that my article about the QRP ATV 13 cm transmitter was published on pages 12-15. I hope that my article inspires people to build this small transmitter. 
In this blog I posted a couple of entries about my ATV endeavours with this device.

The " QRP Nieuwsbrief" is the newsletter from the Benelux QRP club.

Monday, 16 February 2015

Confirmation 28 MHz contact with Greenland

Greenland is an enormous autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans.
With a population of less than 60,000, it is the least densely populated country in the world.
In 2011 I had a digimode (PSK63) radiocontact with Jan, OX3DB on 28.120 MHz and he sent me this eQSL:

Because there are so few radio operators in Greenland this is an eQSL to be treasured.
Up till now I made two other radiocontacts with Greenland (OX3XR and XP3A).

Saturday, 14 February 2015

Fender amplifier

This week I had the opportunity to have a close look at a Fender Twin Reverb amplifier.
This guitar amplifier has been equipped with four 6L6 tubes.

                                     Fender Twin Reverb amplifier, front view


At this moment, the amplifier has three anomalies and is being repaired now : One 6L6 has turned white, most likely due to the loss of vacuum, one magnetotransformer of the reverb unit has a broken wire and a 10k potentiometer has a damaged shaft. 

Chassis after some thorough cleaning

I saw this collection of LP's in Utrecht recently...vinyl ("LP's") is back. A perfect combination with tube amplifiers!

Tuesday, 10 February 2015

Hungarian eQSL

Just received an eQSL from a PSK31 QSO I made with Gabor, HA0NGT, on 50 MHz in 2010.
It is rare since I made only a couple QSO's on 50 MHz in digimodes.
I think, the picture is a nice one and interesting enough to display here:

                                eQSL from PSK31 QSO with HA0NGT in 2010

Thursday, 5 February 2015

Raspberry Pi 2

The Raspberry Pi Foundation's low-cost computer was an instant phenomenon upon its release in 2012, and now, just shy of three years later, it's back with a new one. The foundation has announced the Raspberry Pi 2, an equally cheap, equally tiny computer that's meant for use in a variety of electronics projects (including ham radio) and assisting experiments.

There are two key changes on this new model: its processor is now a lot more powerful and it includes twice as much RAM. What doesn't change is just as important: it still sells for about 35 euro (!).

The Pi 2 is running a quad-core, ARMv7 processor clocked at 900MHz (the foundation says that it expects power users to clock it even higher), and it includes 1GB of RAM. The Pi 2 will support WIndows 10. The original Pi included a single-core, ARMv6 processor at 700MHz and only 512MB of RAM. Aside from that, the new model is pretty much the same as the latest "Model B+" Pi board. It supports up to 4 USB connections, its primary storage is a Micro SD card, and it all fits on a small green board. The Raspberry Pi Foundation says that performance increases will vary depending on what you're doing with it, but on the whole, they're going to be substantial.

The Pi 2 comes with powerful software like Mathematica and Element14, which usually costs hundreds or thousands of dollars.

Friday, 30 January 2015


The Automatic Identification System (AIS) is an automatic tracking system used on ships and by vessel traffic services (VTS) for identifying and locating vessels by electronically exchanging data with other nearby ships, AIS base stations, and satellites.
Information provided by AIS equipment, such as unique identification, position, course, and speed, can be displayed on a screen.

An AIS transponder normally works in an autonomous and continuous mode, regardless of whether it is operating in the open seas or coastal or inland areas. AIS transponders use two different frequencies, VHF maritime channels 87B (161.975 MHz) and 88B (162.025 MHz), and use 9.6 kbit/s Gaussian minimum shift keying (GMSK) modulation over 25 or 12.5 kHz channels using the High-level Data Link Control (HDLC) packet protocol. Although only one radio channel is necessary, each station transmits and receives over two radio channels to avoid interference problems, and to allow channels to be shifted without communications loss from other ships. The system provides for automatic contention resolution between itself and other stations, and communications integrity is maintained even in overload situations.

In order to ensure that the VHF transmissions of different transponders do not occur at the same time, the signals are time multiplexed using a technology called Self-Organized Time Division Multiple Access (SOTDMA).

You can watch AIS traffic on the map here:

Saturday, 17 January 2015

Turkish QSL card

I received a QSL card from the Turkish Amateur Radio Club TA2KK. Operator of the 20 m RTTY QSO in August 2008 was Sencer, TA2AHS.


The QTH of the Club station is located in the Asian part of Istanbul.


Monday, 12 January 2015

50 MHz 10 Watt amplifier

I found some info of a 6m amplifier I built in 2007.
It uses a VHF transistor 2N4933. I made the unit in order to give the SEM35 radio 10 Watts out instead of 1 Watt. The PA can only be used in FM and CW.

                                         Circuit 10 Watt PA for 6 m


                                                           Inside view

                                                              Tronser 30 pF