Akademisk Radioklubb


Month: November 2017 (page 1 of 3)

Soldering course

From time to time we hold internal courses on technical topics in order to increase the general knowledge of our members. Recently,  Henrik – LB5DH, took great initiative in organizing an introductory course in soldering for our members. Soldering is an activity that we do a lot of in ARK, for example when building beacons, antennas or doing general maintenance. It is a very useful skill to have when doing work on projects for the club.

Henrik got in touch with experienced solderers Øystein – LB7IG and Snorre – LA8ITA, who were willing take responsibility for the academic content of the course.  The theory portion consisted of topics such as:

  • Getting optimal heat transfer between soldering iron and PCB/components.
  • How to solder components.
  • What does a good solder-joint look like.
  • Flux – what is it and why do you need it.
  • Solder alloys and their effect on performance and usability.
  • Care and maintenance of a soldering iron.
  • Health and safety hazards and procedures to avoid them.

Øystein – LB7IG demonstrates how to apply solder to a through-hole component.

For the practical portion of the course, the attendees each got a Pixie CW 40 m transceiver kit. The Pixie is a very simple fixed frequency CW radio that will output around 1 watt at 7.023 MHz. As an introduction to soldering for an amateur radio club, we could not have asked for a better kit!

Partially assembled Pixie kit.

Originally, the plan was to solder a through-hole component kit (the Pixie) first, and then move on to surface mounted device (SMD) kit afterwards. This part of the course was postponed due to delivery problems with the SMD-kit.

We are very grateful for being able to loan soldering equipment and a place to use it from Omega Verksted. This came in handy, as fitting all eight attendees into our workshop at the same time would have been very crowded. In addition, we got to loan portable fume extractors from the Elprolab at NTNU through Ingulf, LB1VF. They were indispensable for the continued health of the participants. Thanks to Omega Verksted and LB1VF at the Elprolab for making the course possible!

LA6XTA removing some excess solder.

LB5QG showing off a custom case he made for the Pixie transciever.

LA2QUA brought a display and microscope unit.

Jens – LB6RH placing a throughhole component on his Pixie.

LB6RH doing a test-powerup.

Back to consulting the schematic after the test-powerup failed.

Einar – LB7JH checking out the bill of materials and placement instructions.

Testing the Pixie on a spectrum analyzer.

Local oscillator leakage is quite bad!

TX mode gives approximately 24 dBm out, note that the carrier is a little offset from the receive leakage to produce a 600-800 Hz tone. It also turns out that the output power is roughly 0.25 W (24 dBm) for this specific Pixie (-6 dBm measured on the spectrum after a 30 dB attenuator).

LB6RH and LA6XTA tuning the Pixie to see if they are able to receive each other.

LB7JH inspecting his solder joints.


Overall, the course was a great success, and got a lot of ARKs members more interested in soldering. A big thanks to LB5DH for organizing the course, LB7IG and LA8ITA for sharing what they know, and LB1SH, LA3WUA, LB1MH and LB7RG for acting as teaching assistants during the practical portion. Hopefully, we will repeat this course several times during the upcoming semesters.

Telefonitest 2017 QTH NUTS

Telefonitesten (Norwegian: the Telephony Test) is a Norwegian-only Ham Radio competition occurring every fall. ARK has a tradition of participating in this event, and we find it to be a very good introduction to contesting for new hams.

This year, we decided to try to participate in the contest at a different location than Samfundet in order to avoid being hindered by e.g. sound checks. Thanks to intense lobbying from LA3WUA, we were able to borrow the venues belonging to the local student satellite group, NUTS (NTNU Test Satellite) , at the NTNU campus at Gløshaugen.

NUTS seen from the outside.

NUTS has convenient direct access to the roof of the Department of Electronic Systems at NTNU, including a lift from the ground floor and straight into their venues on the fifth floor. We got the go-ahead after lunch on Friday, started packing at 17.30 NT and had our dipoles and rigs (including a rig and PA borrowed from LA1BFA) ready on the roof by 22:30 NT. Since it gets dark around 16.00 in the afternoon at this time of the year, we could not get any good pictures of the assembly and teardown.

Spiderbeam 15 m aluminium mast used as anchor point for 40 m and 80 m dipoles.

LB5DH, LB6RH and LA6XTA replacing a broken balun at the 40 m dipole.

NUTS 2 m / 70 cm ground station.

Low hanging 80 m dipole for Near Vertical Incidence Skywave (NVIS).

In addition to running the contest at a different location, we had a couple of operators down at Samfundet listening to the 40m and 80m bands using our IC-9100 rig and the Flex 6500 rig, and reporting new calls to the main operators at Gløshaugen. The Samfundet shack and the NUTS shack are fortunately less than 500 m apart (CQ WW rules).

LB5QG and LA6XTA working the receive stations during the third period.

LB5DH and LB5QG listening to QST-LA in the break between the second and third periods.

The operators at Gløshaugen could then focus on calling CQ, and conveniently pounce calls on the other bands that were searched for and spotted by the operators down at the listening stations. This was achieved by creating a privately hosted DX cluster.  ARK’s IRC channel was also diligently used in the coordination effort.

LA1BFA working 80 m in the first period.

LB6RH working 40 m in the first period.

LB5DH working 80 m in period three.

In the end, we got a total of 132 QSOs. While this might not seem like such a high number, the number of participants in this contest is limited (45 unique calls in our log). Success in the contest depends on whether all the participants of the contest can be run at all periods, and on all bands, or whether we are limited by the propagation conditions. Being able to get that single contact becomes important, as the margins are very small. It is imperative to both call CQ and search and pounce at the same time. Being unable to run the last period on Saturday due to sound checks at Samfundet has, for example, normally led us to hit the bottom charts of this contest.

Distribution of QSOs in the two bands run in this contest. The 40m conditions were rather low during the first two periods. Period 1 was on Saturday 13.00-15.00 UTC, while period 2 and 3 were on Sunday 07.00-09.00 UTC and 13.00-15.00 UTC, respectively.

Typically, single operators will switch between the 40m and 80m band after the first hour of the period. We never remember the order of the two. After looking at the plots above, we still don’t know the order of the two :-).

These plots also reveal some interesting facts about the propagation conditions during the contest. The main mode of propagation for 40m and 80m in Norway is NVIS (Near vertical incidence skywave). We chose to employ low-hanging dipoles at the NUTS site to get a high take-off angle. To reach the northern-most parts of Norway, F-layer propagation with lower take-off angle would be desirable, but since the population density is much higher in southern Norway, this was not our main focus.

NVIS propagation is highly impacted by the latitude and the number of sunspots. Since our latitude is high, and the number of sunspots currently is low, the maximum NVIS frequency is likely below 7 MHz during the most of the day. Luckily, as seen in the plots above, we got a small opening at the end of period two that lasted to about the middle of period three.

Beyond this, our theory is that the maximum usable frequency was too low for good 40 m conditions during the main bulk of the contest. From a operator’s perspective, the 40 m conditions during period three were quite interesting. The period started with great conditions on 40 m and lots of contacts. After an hour, the Norwegian calls became faint as the noise floor increased, and by the end of the period, we were suddenly able to hear only European stations. The increase in noise floor and European stations indicate that the D-layer started disappearing, and longer propagation paths via the F-layer started to become possible.

In addition to the plots above, we also looked up address information of the contacts from the Norwegian ham database, found the corresponding coordinates using geopy and plotted these on maps using cartopy. Maps for each period are shown below.

Thanks a lot to NUTS for loaning us their QTH! It was a pure pleasure being able to avoid the interference problems at Samfundet, and enjoy the view and atmosphere of their convenient and airy rooms from the top of Gløshaugen. Thanks to all the operators, thanks to LA1BFA for lending us his PA, rig and hours of his time both during rigging and running the contest, and thanks to the other participants of the contest. We are looking forward to the results.

More photos can be viewed at bilder.la1k.no/telefonitest2017/. This also includes some photos from the initial phase of an attempt at overhauling our 160m dipole, and the photographer going wild with the nice autumn weather.

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