The magic of GPS time for the QMX+

It's almost magical to watch how UTC time drops down from the GPS satellites onto the QMX+ ! Here's 1.5 minutes condensed to only 11 seconds showing just that.

A first-time activation of a POTA park

As a latecomer to the Parks on the Air program, I didn't think there were any unactivated parks in the vicinity of where I live just southwest of Oslo. But the other day I found one which had been attempted, but with too few contacts to count as an activation. I managed more than the required ten, so that is a first for me.

When you love radio and want to do more hiking: POTA

I love amateur radio and I would like to do more hiking - so what's more natural than to take part in the Parks On the Air (POTA) program. I've only recently discovered POTA and how it combines the two: amateur radio and hiking.

Today I went to a park not too far from home. In addition to a short drive it took about a one hour walk in the terrain each way to NO-0497, "Furuåsen og Hagahogget". There is a magnificent view over the Oslo fjord from a trekking cabin there: Hovdehytta. It has a history going back to 1922.

Garden portable with the QMX+

Just a few days ago I had my first SSB QSO with the QMX+. It was from LA to PA - Norway to the Netherlands - on 20 m using a vertical quarter wave antenna.

 

The speaker/microphone is a "For Kenwood" Chinese speaker mic bought for a Baofeng some years ago. I replaced the microphone element with a more sensitive one that I had in my junk box. 

Surprisingly, the speaker gives (almost) adequate volume without an amplifier. The speaker is 8 ohms and connected via two 33 ohm* resistors from the left and right audio outputs of the QMX+. The resistors are the only components in the little square box that the speaker-microphone connects to. Initially I felt no need for any more audio amplification, but after some more use, I see the point in more power output as the audio easily gets distorted when the volume is increased.

Why didn't I come up with this simple upgrade to the QMX+?

This is an upgrade to the QMX+ which is so simple that I keep saying to myself: why did it take so long for someone to come up with it?

It consists only of doubling the PA transistors. The original 4 BS170s are paralleled with 4 more as shown in my implementation in the image. Very simple!

It is, as far as I understand, the brain child of Roelof PA0RDT and is described in detail on the QRPLabs website. I essentially followed those guidelines, and got more or less the same results as reported there.

There are several advantages:

• Approximately doubled output power
• More robustness to applied voltage. My QMX, wired for 9 Volts, now runs fine on 11 and more Volts, with a current limited power supply (approx. 2 Amps). 

I have had many FT8 contacts with it - where the transmitter is on continuously for 13 seconds - and have not had any problems. The only downside that I have heard of is slightly reduced power on 6 m due to the effect of the increased gate capacitance with two instead of one transistor.

Radio amateur endorses my latest book

Last fall I published the book "The Imagined Conflict". One of the endorsers is John Lennox, with whom I share the radio amateur hobby. His callsign during his most active days was GI3NSP,  at present it is G3NSP. 

Here's his commendation from the book's webpage:

“Holm’s book is an excellent addition to the literature on science and religion. With a delightful Scandinavian flavor, and with the keen insight of a practicing research physicist, Holm takes a balanced, three-pronged approach to the topic—historical, scientific, and philosophical. This book is a model of fair enquiry, and I thoroughly recommend it to anyone interested in understanding how science and the Christian faith can both coexist and thrive in fruitful dialogue.”

—John C Lennox, Emeritus Professor of Mathematics, University of Oxford

Thanks, John!

 

Do deer like antenna wires?

Our garden is frequently visited by roe deer. They like to trek along the little brook that runs at the edge of the garden. Usually that has few consequences.

But this weekend as I was about to contact stations during the CQ160CW contest, I noticed that nobody could hear me. I heard many stations, but nobody seemed to hear my signal.

The Imagined Conflict

I have a new independent blog named after my book "The imagined conflict". The book was published in November 2025 and is a revised translation of a book first published in Norwegian in 2021 and in a second printing in 2022. 

The new blog may be reached by clicking here.

Science with Overtones

Science with Overtones:
21 Natural Scientists and Their Belief in God.

Scientists with a belief in God have played a central role in the development of science for more than four hundred years. Some might think that belief in a creator God and the practice of science must have been a source of conflict, but the stories of the scientists tell a completely different story. They had a divine perspective on science, and it made their work better, not worse. Be inspired by 21 of the world's most important scientists!

The book has two authors. First, Professor Sverre Holm presents the scientist's life's work and beliefs, then Sven Aasmundtveit reflects on what this can mean for us today.

The book is in Norwegian and in sale from October 30.

My Ruyage UV58Plus changed into a completely new radio

New look (M70CM 3.2/P2.0)

I bought the Ruyage UV58Plus (also called Radtel 890) in August 2023. I liked its display as it would show both the frequency and the name of the station at the same time, and many Chinese handheld transceivers don't do that.

On the other hand, its scanning function wasn't very good, so I was a little disappointed. It sensitivity was also poorer than that of my Baofeng UV-5RE. But at a cost of 34 Euros + VAT, it was OK.

But that was before I found out that its firmware could be updated. I had originally V1.33, 2023-02-10. The images below show it with V1.35 2023-10-20.

The surprising faith of scientists

Equations representing many of the scientists in the book

"The surprising faith of scientists" is the tentative title of a book manuscript just submitted. 

The book stems from a discovery I made some time after I had completed my university studies where I had studied theories named after the likes of Pascal, Ampere, Faraday, Maxwell, and Kelvin. The surprising thing was that all of these were devout Christians. It would turn out that there were many more of them.

The magic of adaptive filters in amateur radio

Examples of a speech signal (top),
a sinusoidal, and noise (bottom)

Radio amateurs have been using adaptive noise reduction and adaptive notch filters for decades. They came with the advent of audio digital signal processing. 

Few however, understand how different they are from ordinary frequency selective filters and for many they appear to do something magic, very different from ordinary filters.

Customize your own list of favorite screens for the Multi-face GPS Clock

Fav 2 subset with 11 entries (Example in text has 9)

The Clock subset menu of the Multi-face GPS Clock gives you a choice already between:

• All, 50 screens
• Fav 1, 34 screens
• Fav 2, 9 screens
• Calendar, 13 screens
• Clocks, 27 screens
• Astro, 17 screens
• Radio, 12 screens 

QMX+ mechanical improvements

My QMX+ has some minor mechanical improvements:

1. Slimmer knobs. I decided to replace the knobs as I often touched the bottom one while adjusting the top one and vice versa. The slimmer knobs solved that. I found knobs on AliExpress with the same looks, only a smaller diameter as the image shows. Unfortunately they don't have screws, so they aren't so well attached as the original ones.
2. Folding laptop feet which I first saw on the AE5X blog.

Why is speech quality so poor in DMR, D-STAR, and System Fusion?

Example of a speech signal which transitions
from an unvoiced to a voiced sound

Digital VHF and UHF communications is increasingly popular among radio amateurs using DMR, D-STAR and System Fusion. 

Very few radio amateurs, however, have much understanding of the signal processing required to compress a speech signal so it can be transmitted with the low bit rates available. Here is an attempt at an explanation.

My favorite faces for the Multi Face GPS Clock

Weekly progress bar with Monday as day 1
in week 9 and yearly progress bar
as of day 56 in the year.

Among the 50 different faces (or screens) now implemented on the Multi face GPS clock, it is hard to select favorites. 

So I start with the latest one that was implemented, i.e. the progress bars for week and year shown to the right. It was new in version 2.3.0 dated 2025-02-04.

A QMX+ coming together

I got an unassembled QMX+ for Christmas this year, and here are pictures of it coming together. First the winding of toroids for the low-pass filters:

The unphysical free-space path loss

Propagation of wave energy to distance d, 2d, 3d
 showing how the size of the surface that the energy
spreads over increases in proportion to 
d², (2d)², and (3d)²

Many places it is stated that the lower the frequency, the smaller the free space loss. 

This is very counterintuitive, because if one solves the wave equation, the amplitude of the solution is independent of frequency. The physics of the problem is that intensity just falls with distance squared according to how the surface of a sphere increases with the radius as shown in the figure.

The Friis formula used in link budgets says something else. It gives received power, Pr, as a function of transmitter power, Pt, receiver and transmitter antenna gains, Gr and Gt; wavelength, lambda, and distance, d:

The Little Known Fourth Method of Generation of Single-Sideband Signals

Envelope Elimination and Restoration, from Kahn 1952 

There is a method for SSB generation which is now becoming popular with digital signal generation and digital output stages. This is the Envelope Elimination and Restoration method or Polar Modulation method. The signal is interpreted as a complex signal in the polar format, i.e., with an envelope and a phase.

This method is receiving renewed interest among radio amateurs as it is used in the SSB implemention of e.g. the interesting QRPLabs QMX transceiver. 

In the QMX a single frequency signal (the phase) is generated in the digital domain and then phase modulated (upper branch of figure). It then has a digital output stage with very high efficiency as it only switches between on and off. The output stage is amplitude modulated with the envelope signal from the lower branch.This gives a much more efficient power amplification than is possible with the three conventional methods.

The three methods

How does it compare with other methods? In 1956, Donald K. Weaver, Jr. wrote a paper with title "A Third Method of Generation and Detection of Single-Sideband Signals".

v2.2.0 Multi-Face GPS-Clock

A few new screens:

• NextEvents() - New screen showing Next Equinox/Solstice, Easter, Lunar/Solar Eclipses in sorted order, i.e. sorted after date as shown to the right
• SolarEclipse() - New screen showing solar eclipses for this year and coming years (table-based until 2030)
• Equinoxes() - New screen for time of equinoxes and solstices

Demo mode now has a choice of increase, decrease, or random next screen number (selectable in Secondary menu).

More languages selectable: {"en", "es", "fr", "de", "no", "se", "dk", "is"}. Any language with max 4 special letters in alphabet can be implemented.

Better accuracy:

• More accurate prediction of sun rise/set times
• More accurate formula for Mercury, Venus, Mars, Jupiter magnitudes in clock_z_planets.h, now follows Meeus [thanks Richard]

Now runs on Adafruit Metro Express (M0). This makes it much faster for the Hebrew calendar in particular.

And some more minor fixes, see details on Github.