Monday, January 27, 2020

AM QSO party last weekend

After a post from MW1CFN John I got interested in this event. Most radioamateurs never ever use AM mode to make QSOs with. Except those who are collecting old WW2 equipment. A(mplitude) M(odulation) mode was the original way to make phone (voice) QSOs over the air waves till SSB and FM would become more populair after WW2. However there is a dutch AM net most time every sunday morning, most of the participants are using old or homebrew equipment. There are still a lot of AM enthousiasts all over the world...

I was planning to be active saturday late in the afternoon, but as you can read in my previous post I ran into problems with a defective fuse. By the time it was all fixed there was no time left to get on air. So, I attended the AM QSO party sundaymorning. A good test was to receive some AM stations in the dutch AM net. I have to write that the stations with the best signals and excellent modulation were the users of old WW2 equipment. Those old BC669 and GRC9 radios sound really good. I also heard some with Geloso radios, but I liked the modulation from the old radios better.

First QSO was on 20m with CT4RK Carlos from Portugal. Carlos told he had some problems the day before. And from the sound of his modulation I think something was still wrong, though it improved a little along the QSO.

My goal was to work fellow blogger MW1CFN from Wales. We tried on 80m first, but there was no propagation. When I was calling on 40m John told me he could hear my signal but had to change antennas. Anyway, we managed to make a QSO on 40m AM after all....mission accomplished.
John also made a recording from my signal after the QSO.

I was not really impressed by the AM modulation so far. But had a QSO with M0XTK which went a lot better. At least his modulation was very good understandable...

Well, I had a lot of fun with all these AM QSOs. But I didnt have the feel you could have with an old tube radio. The sound is just too clean with all these filtering features. The radio audio setup is for SSB and digital modes. For AM receive you should have your audio a bit wider, as wide as possible I think actually.

Some interesting links if interested:

List of stations worked:

YO9AYN     20m AM
G0OVU      40m AM
M0XTK      40m AM
MW1CFN   40m AM
PI4SRS      80m AM
CT4RK      20m AM

Sunday, January 26, 2020

Oh no?

Oh no....what happened here. I was transmitting and suddenly the radio was off! The screen was black and whatever I did it didn't switch back on....

The first thing you think of is.....the power supply. So I took my multimeter and measured 13,8V on the PS terminals. No failure. Then I measured the terminals from the distributionblock, voltage.

Could be 2 things. The fuse or the electronic over/under voltage device. So I started at the fuse. Measured the fuse with a ohm meter, no problems at all, strange....put it back into the fuse holder and the radio switched back on!

Problem solved you would think....

No, as soon as I started to transmit the radio switched off again! A strange malfunction...

So, in my life as electrician I once heard about old worn fuses. Technically a fuse will hold forever, but in reality when the current through the fuse is almost as high as it can hold the fuse will get warm and will suffer from constant expansion and crimping mechanically till it gets worn and breaks.
The fuse I use for the terminal distributionblock was 20A, close to the 18A a IC-7300 is using when transmitting. So I fiddled a little with the fuse and the radio went off and on....a clear case!

I wanted to know why I couldn't see any breaks in the fuse. Left the 20A fuse, you can't see anything and using a ohm meter it measures fine. At the right the same fuse touched by a small screwdriver, you clearly see the problem now...

The problem however was that I had no spare fuse! Stupid was to late to get to any shop and they are closed at sunday. Luckely an old colleague phoned asking if I could tune two CB antennas for garbage run cars. He had a spare fuse, just the one I need. So he and his mate were more then welcome. I tuned their antennas with the MFJ259 analyser and got the fuse(s) for free, everyone happy ;-)

These guys are really crazy actually. Using a old BMW 7 series to drive from the Netherlands through Denmark, Sweden and Norway just for fun in the middle of the winter. They have no idea what temperature it is in northern Norway I think at this time of the year.....besides that these are old cars using lots of fuel. A complete different adventure compared to our boring radiohobby...

Anyway I have a good quality 25A fuse now. It has a better designed calibration wire inside that can hold the stress much longer. I think my old 20A fuse was some chinese cheap quality after all...

Wednesday, January 22, 2020

My LoTW app

Just want to point you to another nice amateurradio app. This one is made by SV2RMK Dimitris. It is  a very useful LoTW viewer app for your phone and/or your tablet (apple/android).

I particulary like the QSL feature. You can even save the QSL if you like...
Actually this is a graphic shell to view LoTW, something I miss in LoTW itself.
Find the app in the appstore. Have fun!