Lars Thunberg

This is the homepage of Lars Thunberg in Sollentuna, Sweden. Amateur radio callsign SM0TGU e-mail lars(at)larsthunberg.se
For information about my satellites and amateur radio activity please see this page where most of the info are in english. Also see all the posts about amateur radio or use the web page search .

My linkedin page is http://www.linkedin.com/pub/lars-thunberg/1/442/769

Domänen larsthunberg.se ägs av Lars Thunberg, Sollentuna. Kontakt via e-mail   lars(snabel-a)larsthunberg.se

Om du letar efter ”rätt” Lars Thunberg kan jag nämna att födelseort är Mellösa utanför Flen och födelseår 1972.

För arbetsrelaterade kontakter hänvisar jag till LinkedIn:

Amateur Radio

New GFK glasfiber tube Aug 2023

During August 2023 and removed my old GFK glasfiber tube and replaced with a new one – this one from Funk Elektronik.

Here are some pictures during the 3 hours of work…

First remove the antennas and the old tube:

Then up with the new tube:

Then up with the antennas and support bom for cables. Here are several pictures from different angles:

Amateur Radio

DIY 5 element UHF Yagi of DK7ZB model

For my SatNOGS station I have built a lightweight 5 element UHF Yagi of DK7ZB model according to this 50 ohm version.

Schematics here:

Some construction notes:

Use a good coax connection for the driven dipole. Here I use an old 10 mm dipole from an LFA loop antenna:

I’m using 32 mm PVC pipe and pipe holders for the elements that are 6 mm alu pipes/tubes. The PVC pipe is the 1,8 mm version for water, not the version used for electrical installation.

Finished antenna below. It gives a very good SWR, under 1.3:1 for 10 MHz bandwidth 430 – 440 MHz.

Amateur Radio

3 el UHF lightweight Yagi

This 3 el UHF lightweight Yagi by RA3TOX can be built with low cost materials like 20 mm PVC tube and tube holders as element holders. The element can be made of 3.2 mm aluminium welding rods. Making a second yagi on the same boom and it becomes a X-yagi, with correct made phasing cables.

I have built one X-yagi version and tests on the ground (see picture above) was very good, when I tested it as a SatNOGS antenna. Unfortunately, something broke when I mounted it on the mast so it is not in use.

The driven element (loop type) was kind of hard to get correct, I made several versions before I got the correct SWR for 436 MHz.

This is the drawing I used:

  • Original drawings, calculator and design by RA3TOX
  • Used by PE0SAT for his SatNOGS station. Link here.
Amateur Radio

Satellit yagis tracking Greencube

Satellite antennas tracking Greencube – May 2023.

Amateur Radio

SatNOGS VHF/UHF Moxon test

Test of VHF/UHF Moxon antenna for my SatNOGS station. Read more here: https://community.libre.space/t/test-of-new-antenna-for-station-858-sm0tgu/10131

Amateur Radio

Change mainboard Rot2Prog

Step by step for changing the mainboard of a Rot2Prog rotor controller. Time aprox. 20 minutes.

First of all – remember to point your antenna to Azi = 0 degree and Ele = o degree! If anything goes wrong you know 100% where your antenna is pointing.

Remove the top cover and then the old mainboard (see red markings)

Carefully move the PROM from the old mainboard to the new one

Lift up the old mainboard

Lift up the cables marked in red from the old mainboard in place it at the same location on the new mainboard

Place the new mainboard in the metal enclosure and align in so all the push buttons on the front is working. Tighten the board screws and then mount the top cover.


Amateur Radio

Koss SB-45 Headset for IC-9700

Koss SB-45

I have been looking for a headset for my IC-9700 and read that many are very pleased with the Koss SB-45 (SB/45) PC headset with electret microphone element.

I got one for 20 EUR via the Swedish eBay site Tradera. I made a DIY adapter for the Icom standard 8-pin Mic connector – just connected pin 7 ”Mic ground” and pin 1 ”Mic input” to a 3.5mm female connector.

8 pin MIC adapter DIY

This is the pinout for the Icom 8 pin connector:

Icom Mic pinout

Here are some very short audio samples – first with the standard Icom mic and the second with the Koss SB-45. I’m using USB and maybe not exactly on the correct frequency when I did the recordings:

Icom HM-219 original mic
Koss SB-45 controlled with VOX

Some useful links: