Friday 17 May 2024

Radio Caroline

Lately I have been experimenting with a KT0936M module on the medium wave. I discovered that Radio Caroline puts a firm signal strength at 648 kHz at my QTH. The music they play is from the 60’s-90’s. Like to hear their music through my 5 Watt tube amplifier 😊

Here   you can read that Radio Caroline returned to the medium waveband on 648 kHz AM as a legal broadcaster at the end of 2017, after applying for, and being granted, the Ofcom licence for the Essex and Suffolk areas of South Eastern England. Radio Caroline is using an RF power of one kilowatt from a Nautel ND2.5 transmitter.




Thursday 2 May 2024

First steps in satellite communications

The Satrover QO100 transverter enables you to use the geostationary OQ100 (Es’Hail-2) satellite. I was able to explore this equipment with Gerard PA2G. With the use of an IC-705 and the satellite dish aimed at the OQ100 satellite (elevation 27 degrees, azimuth 153 degrees in the Rotterdam area) we were able to receive satellite SSB/CW/FT8 signals at appr. 10 GHz (converted to 144 MHz by the transverter).

Making an uplink at 2.4 GHz will be the next step.

SATROVER transverter and LNA/Helix antenna

Saturday 20 April 2024

Roger's Scrapbook

Some of my projects on this blog are inspired by the radiowork of Roger, G3XBM. I like his transverter designs in particular.

I found that Roger collected a lot of his work in his Project Scrapbook (currently issue 5). It contains a lot of nice experimental data and good projects.

You can find the scrapbook here:

Hope you like the scrapbook as much as I do.

Monday 8 April 2024

QRV from Attica

During a recent trip to Greece (Attica, Agia Marina) I was able to use one of the radio repeaters near the capital of Athens. The repeater has callsign SV1B and is located on Mt. Pentelikon. RX frequency is 145.775 MHz and shift is -600 kHz. CTCSS is 88.5 Hz. 

The Quan Sheng porto worked fine and with callsign  SV1/PA2RF  I could made some clear qso’s a.o. with SV1IUY.

Tuesday 19 March 2024

Platform for KT0936M experiments

The little KT0936M receiver IC has surprised me. To find out and explore the possibilties of this chip I made a simple platform.

A multiturn potentiometer enables me to select any of the more then 20 FM and SW bands. This KT0936M is a DSP chip and therefore frequency selection is very accurate. I  listened to stable, small band, 14 MHz CW signals (in AM mode).

Today I connected an LF amplifier with a TDA2050 IC. I was surprised by the quality of the sound.

Anyway, I have to discover a lot.

How can I display the exact receive frequency. There is no Fout pin. Also how can I receive Single Side Band signals. This chip does not have an IF since it it is a DSP chip. So, how can a BFO be added. At which operating frequency ?

Anyway (2), I am enjoying the reception of the broadcast AM stations from all over the world in the evening hours. The fading, the different languages, the memories..

Friday 9 February 2024

Little Medium Wave radio

From a popular supplier of electronic goodies, I purchased a tiny MW/FM radio (not a DIY kit). It does not have a loudspeaker but should be used with headphones. I was interested in the performance of the MW part of the radio. 

And that really surprised me. It is a very sensitive receiver for the MW/AM band (530-1600 kHz) using a ferrite rod antenna. I thought nowadays the MW band should be almost 'dead'. But that is not the case. On this small radio I received a lot of broadcast stations past days. 

I removed the battery case from the radio to find out what was the engine in this receiver. It turned out to be the IC  KT0936M. After some research I found that the KT0936M is KT Micro's 3rd generation of integrated mono full band FM/MW/SW receiver chip supporting mechanical tuning with embedded MCU. The chip works with a supply voltage of 2.1V till 3.6V, so 2 AAA batteries can do the job. 

To my surprise the IC covers a wide range from 500 kHz - 110 MHz! The chip has been designed to facilitate following bands: 

- Maximum two FM bands with configurable FM frequency range within 32MHz-110MHz

- Maximum two MW bands with configurable frequency range within 500KHz -1750KHz 

-Up to 14 SW bands with arbitrary frequency range within 1.75MHz – 32MHz


The KT0936M has a high sensitivity, high signal-to-noise ratio and low distortion. 

KT Micro provides following values for sensitivity:

1.6uV EMF for FM
16uV EMF for MW
13uV EMF for SW

IC KT0936M provides direct and simple interface to support mechanical tuning. A pre-programmed low cost EEPROM can also be used to configure the radio band settings. No external MCU is required. 

If you search on the internet for KT0936M designs, you can find out how the specific bands can be selected (use of resistor network). The IC should be useable for our radio amateur shortwave bands. At least a BFO has to be added to the design.  . 

Thursday 18 January 2024

Danish eQSL's

Radiofriend Gerard, PA2G, made 2 FT-8 Special Event QSO's with Denmark. The event concerned the inauguration of King Frederik X. I think the eQSL's are quite special.

Thursday 30 November 2023

Solar flare hitting Earth

A powerful M9.8-class solar flare erupted from the sun (AR3500) on Wednesday (Nov. 29) at 2:50 p.m. EST (1950 GMT), hurling a super-hot plasma eruption known as a coronal mass ejection (CME) toward Earth. The flare is expected to hit Earth today (Dec. 1, 2023).

Hopefully our internet and radio communication systems can withstand the amount of electromagnetic energy that is brought in by this -almost X-class- solar flare

Note: I have not heard of any damage to communication systems whatsoever.

Monday 30 October 2023

DvdR 2023

Last Saturday, Oct. 28, I was part of the ‘NL-post’ team at the DvdR (Day of the Radio Amateur) in Zwolle, IJsselhallen. 

I was there with Thieu, NL-199, PA0M and Gerard, PA2G. It was good to speak to fellow radio enthousiastics and see lots of old and new radio stuff. It was remarkable that my homebrewed  BITX20 from 10 years ago - built in ‘Manhattan style’ - draw a lot of attention.

NL-Post stand with PA0M and PA2G

Scouting girls making worldwide radio contacts during CQWW SSB contest

Nice antenna designs

My BITX20 caught some attention

Monday 26 June 2023

SDR receiver exploration

Great fun with SDR Receiver MSI2500 in combination with SDRuno software. I am exploring  the possibilities of this nice toy.

The SDR receiver (frequency range 30 - 1000 MHz) has 5 antenna inputs each with its own bandfilter

SDRuno software in action ( Repeater PI2NOS, 430.125 MHz selected)

Experiment with E-field antenna for low frequency signals (< 10 MHz ).

I wrote an article for the Dutch radiomagazine Electron, NL-Post, Nov. 2023, about this SDR receiver: