2018-08-13 Trying to receive amateur radio through local interference 1 week ago
This evening I tried several things to improve my chances of actually receiving anything other than the loudest stations in the upcoming SCC RTTY contest. First try was with a borrowed receive loop indoor and using an HF upconvertor, an rtl-sdr dongle and gqrx as receiving software. This did not work for digital modes: letting wsjt-x (FT8 software) 'listen' to the audio output of gqrx gave no decodes. Interesting detail: looking at the right piece of spectrum for FT8 showed that the frequency wasn't 100% stable, with frequencies slowly changing. Touching the rtl-sdr gave a bump in frequency. Another attempt was with the loop indoor and reception on the FT-857D radio. Reception of a strong SSB station seemed somewhat better on the loop, but I heard no improvement of weaker stations. So I moved the loop outside to the end of the garden and layed a long cable back to the radio setup. This made interference worse! It was already dark so this was not related to any solar panel setup, but some other source of interference on HF. The loop is supposed to receive less local interference but I could not get it to do that this time (it did work for SSB some other time).
2018-08-12 Making the HP DPS-700GB power supply less noisy 1 week ago
The HP DPS-700 GB power supply adapted to feed the linear amplifier has no own internal fans so I connected a recycled 50mm PC fan. Which runs at full speed which is a lot of noise. I ordered a 12 volt fan control module on-line so it can run slower and keep the noise down a bit. I'll probably replace the current fan with an 80mm PC fan and set a low minimum speed. The air has to move as the power supply has no internal fans and is quite good at a thermal shutdown. But as long as things don't get warm it would be nice to reduce the noise as this was very noisy.
2018-08-12 More output power for PE4KH: I bought an HF linear amplifier 1 week ago
The reason for making the HP DPS-700 GB powersupply deliver a somewhat higher voltage and lots of amperes is that I made the decision to buy a HF linear amplifier. With such a device I get more output power on HF bands which should increase my chances in radio contests. I have been looking at new and secondhand linear amplifiers for a while. Since this market is dominated by US customers most amplifiers will give 1000-1500 Watts output power at a serious price. The legal limit here in the Netherlands is 400 Watt unless I request a special license which will never happen since the radio station is surrounded by other houses. But there isn't much on offer below 400 Watt output power. I found RM Italy which sells linear amplifiers for CB and radio amateur use at more reasonable amounts of power and at a better price-point. I selected the RM Italy HLA300V plus which should give 300 Watts on HF bands. I bought it online and it arrived fast. After soldering some cables to the power supply I was able to use it and it works as intended. On the 20 meter band and 10 meter band it works with the endfed antenna (which can take 400 watts). On the 40 meter band it goes into protection mode instantly. It turns out the amplifier is quite sensitive to SWR problems, the endfed gives a 1:1.5 SWR. Maybe I can improve this a bit, the resonant point is below the 40 meter band. Giving it 5 watt input power in digimodes will make 5 of the 7 output power LEDs light up. To get it to light up 5 LEDs in SSB mode I need to give it 10 watts power in that mode. Propagation wasn't great this weekend so I spent most time in FT8 mode. With the help of the new amplifier I was able to get two new countries in the log: V51MA in Namibia and 9G5AR in Ghana. The receive side is currently a different story. Interference levels are at an all-time high. The way I currently get reception for FT8 is by using the UTwente WebSDR for the receive side and feeding the audio to WSJT-X. With the delays and audio-processing introduced by the WebSDR I still get better and more decodes than from the local receiver. For contesting that setup is not going to work. Most contests have a rule that all equipment for a contest station has to be on a limited area. For example the upcoming SCC RTTY contest has the rule:Read the rest of More output power for PE4KH: I bought an HF linear amplifierAll operation must take place from one operating site. Transmitter and receiver must be located within a 500-meter diameter circle.I'm looking into using a receive loop to have less interference on reception.
2018-08-06 Rich chunky amps from a HP DPS-700 GB server power supply 2 weeks ago
At a hamfest a scouting group was offering a HP DPS-700 GB power supply for the nice sum of 5 euro. A quick search with google found information about the pinout so I bought it. This is a power supply that can deliver 56 Ampere at 12 Volts, and the 12 Volts can be adjusted upwards somewhat. As usual with projects like this the power supply lived in the stack of projects for a while, but today I got around to testing it. Finding the pinout again was a bit hard, but I found the pins again at HP DPS-700GB 80mm fan shroud - Thingiverse which includes the simple modification to make the output voltage go up. As this power supply has no internal fans and will stop fast due to internal overheating if not cooled, I set it up with a recycled computer fan. Power supplies like this will always be active in systems with enough fans to push air through the whole chassis. The first test gave me 12.1 Volt. After adding a 1.5 kOhm resistor it went to 13.27 Volt. In theory the maximum current may have dropped as a result of this modification, but my best guess is that it can still deliver 50 Ampere.
2018-06-30 New 2 meter distance: 483 kilometers 1 month ago
While trying to get an idea of how much interference I have on the 2 meter band I still worked on my distance records: I had a contact with G8GXP which is a distance of 483 kilometers, a new record for me on the 2 meter band. This is with S5/S6 interference on the 2 meter band as long as the sun is more than a bit above the horizon, which at the moment is very long. Some ferrite added to the solar power convertor already helped, but I guess the solar optimizers also need some work to clear the 2 meter band again.
2018-06-27 Recorded the ISS contact today 1 month ago
Today was an ISS contact with Werner-Heisenberg-Gymnasium, Leverkusen, Germany and Schickhardt-Gymnasium, Herrenberg, Germany and most of the contact was going to be within range for me and it was at a usable time. So I set up gpredict to track the ISS and the receive frequency and set up audacity to record the results. Which weren't great since 2 meter reception is now influenced by recently installed solar panels on the house next door.
Listen to audio attachment:
2018-06-26 Interesting video about amateur radio 1 month ago
A nice video I found from Essex Ham via Journey into Amateur Radio (Pete M0PSX) where Pete narrates slides from earlier presentations he gave on his specific journey in amateur radio.
2018-06-17 More kilometers distance into Australia 2 months ago
This evening I made an FT8 contact with VK7AC which is a new distance record: 16918 kilometers. Which is an improvement over the previous record: 16581 kilometers to Melbourne. With Australia being huge I'm not surprised distances can be very different. The contact was hard to make but callsigns and signal reports got exchanged eventually. This was on the 40 meter band so that's also a new band for that country. In the rest of the weekend I made more FT8 contacts on different bands and some SSB (voice) contacts to several active stations. Noticable was that several high-power stations were active on the 10 meter band Friday evening enjoying the band opening.
2018-06-04 First 'Sporadic E' contact on 2 meter 2 months ago
As guessed when I got earlier personal distance records with FT8 on the 2 meter band bigger distances are possible with 'Sporadic E', a condition in which even higher frequencies can be propagated through the ionosphere. This evening G8EOH came back to an FT8 cq on 2 meter and I found out that gave me a new distance record: 342 kilometer.
2018-06-04 An active weekend on the 10 meter band, Faroe islands in the log 2 months ago
This weekend had enough time available to be active on the radio. And the 10 meter band was open again, just like the evening opening on 10 meters three weeks ago. This weekend the 10 meter band cooperated most of Friday evening, a few hours Saturday morning and most of Sunday afternoon and evening. Especially 10 meters FT8 was busy and I worked a lot of European countries on the 10 meter band. On Thursday evening I had 15 countries confirmed (lotw or paper qsl) on 10 meter for my call PE4KH, on Sunday evening that number was 25. I added the Faroe islands to the log Sunday (also on 10 meter FT8) when I saw OY1DZ active and had a contact. Not yet confirmed, I have requested a card via the OQRS system in use for OY1DZ and other calls. According to that page the LoTW confirmation will also happen soon. I also got a few voice contacts in the log: special event calls and world wide flora and fauna activations are always nice to have. The flora and fauna location spff-450 activated by SP5KD/P was hard to understand at home so I used the utwente websdr to receive and the transmitter at home to transmit.
2018-05-25 Going full duplex with amateur satellites, part 13: receiving a linear satellite transponder / SO-50 without the preamp 2 months ago
This evening another try, this time without the preamp. And tried receiving a linear satellite transponder. This makes things even more complicated as I have to look at one display (gpredict) to have an idea where to aim the antenna and another display (gqrx) for the waterfall display. Maybe both can be on the same screen with a lot of resizing. The first pass I tried was a pass of the FO-29 satellite which has a linear transponder. It was not a very high pass so all reception was through a house. I did hear morse first, and later saw signs of USB signals in the passband. Signals were weak and noise was high. I was almost able to understand one callsign, a 9A.. callsign (Croatia). The other pass I tried was a pass of the SO-50 satellite which is a narrow FM satellite. Signals were weak for narrow FM so I had to keep turning the arrow antenna to get the polarisation right. I could hear spanish and english callsigns. I recorded the SO-50 pass and noted the audio looked very distorted in audacity. Maybe I can improve the audio somewhere in the chain and get things better.
2018-05-24 Going full duplex with amateur satellites, part 12: picking it up again 2 months ago
So last year I wanted to get back on amateur satellites and bought some hardware that would enable me to go full-duplex: receive and transmit at the same time. The most important part is to get the receive side working. This evening had a pass of the SO-50 amateur satellite and a pass of the Fox-1D satellite right after another (with some overlap). And it's dry and a reasonable temperature to be outside with laptop, preamp, rtl-sdr stick and arrow antenna. Signal levels on narrow FM are still very faint and hard to hear, so I guess I am at the limits of the rtl-sdr for weaker signals, even with the preamp.
2018-05-20 I participated in the EU PSK DX Contest 2018 3 months ago
This weekend I had some time to participate in the EU PSK DX Contest. Conditions did not cooperate very well. First I thought local qrm was making me hear only the loudest stations but comparing it to the Utwente websdr I was hearing about 'everything'.Read the rest of I participated in the EU PSK DX Contest 2018Total number of QSO in your log is 41, Including 0 QSO with errors, Valid QSO - 41 Band QSOs Dupes Points Mults 160 0 0 0 0 80 0 0 0 0 40 28 0 56 39 20 13 0 25 21 15 0 0 0 0 10 0 0 0 0 ====================================== Total 41 0 81 60 Claimed score is 4860 points
2018-05-14 Back to the 10 meter band 3 months ago
The 10 meter amateur band (from 28.0 to 29.7 MHz) is the HF band where I started making the first HF contacts in 2014 but after that HF propagation went down and I had to go to lower frequencies and bigger antennas. But there are short periods of better propagation and this evening I tried FT8 on the 10 meter band again and made two contacts into Norway. I even received signals from Brazil so propagation was ok, mostly along the 'greyline' which is the line over the earth between the areas in the sun and not in the sun and causes some more propagation.
2018-05-07 I participated in the ARI International DX Contest 3 months ago
Last weekend I participated in the ARI International DX Contest. Before the contest I was looking at the option of trying the tlf contest software and operating phone (voice) but adding the definitions for scoring this contest to tlf turned out to be not possible at the moment and at the end the weekend was filled with enough other things that only a few hours of operating RTTY were left. Propagation wasn't very cooperative and I first was blaming local interference until I noticed that the same lack of signals was showing in other places and twitter was filled with aurora pictures, so a solar flare had blocked propagation. In the end I made 43 contacts and entered in the 'single operator RTTY low power' category. Low power on an Italian scale: below 100 watts.
2018-05-01 Getting amateur satellite contacts into LoTW correctly 3 months ago
A very good bit of info just flew by on the amsat-bb mailing list: Logging Satellite QSOs with Logbook of the World - AMSAT-NA. Complete with screenshots and needed steps, how to create an ADIF file (which I could import into CQRLOG) with the satellite-specific fields set to the values needed by LoTW to make it a valid satellite-contact. CQRLOG has no support for satellite-specific contact information, so for me the workflow for these contacts would be to create an ADIF file as above in LoTW, upload it, and import the ADIF file in CQRLOG and not upload it from CQRLOG. Now to find time, energy and nice weather to get on the satellites again.
2018-04-26 More radio maps and their limits 3 months ago
The PE4KH website has maps of the locations where I contacted radio amateurs all over the world. The maps with generated images are created by exporting my locators worked/confirmed from cqrlog and using gcmwin for linux with a whole set of different configurations to plot the results. But now the 2 meter band has been added and on that band a 'record distance' is not as far as on HF. On HF my current distance record was a contact with Australia at 16581 kilometers. My current distance record on the 2 meter band is 363 kilometer in Germany. Quite a different scale! So the maps part has been enhanced with a 2 meter contacts map, but gcmwin can't use 6-position maidenhead locators so the map is quite coarse compared to what I want. I don't know the solution at the moment to improve this. The recent qso map PE4KH does show the more precise gridsquares when available in the log, so maybe that page needs distances added.Read the rest of More radio maps and their limits
2018-04-24 Building my own balun, part 7: Better measurements of the result 3 months ago
Read the rest of Building my own balun, part 7: Better measurements of the result
2018-04-23 Building my own balun, part 6: Redo and some success: a working antenna again 3 months ago
After the previous measurements showed the balun and dipole under the roof weren't acting as a perfect combination. So time to do a few things better: more windings, less leftover wire and a switch to a voltage balun. Yes, other sources indicate a current balun is better, but I decided otherwise. The Fritzel balun turned out to be a voltage balun after I removed it from the dipole antenna. So I used the instructions at 1:1 voltage balun by VK6YSF to rebuild it as a voltage balun and I made sure the wires were shorter in the end. Getting the shorter wires in the right places in the case did get me some slightly burned fingers! Success is currently defined as "I can transmit a carrier on the 20 meter or 10 meter band and the SWR meter of my radio only goes up a few segments" which isn't very scientific, I will need to do the rest of the measurements with the SWR meter to be sure.Read the rest of Building my own balun, part 6: Redo and some success: a working antenna again
2018-04-16 Building my own balun, part 5: First tests of the result 4 months agoOlder news items for tag hamradio ⇒
big common mode choke in the mix makes the combination show better SWR curves (still not what I want) but with the frequency with the best SWR still too low. This suggests (to me) two things: I need more windings on the ferrite core and less extra wire length from the core to the connectors. Time for a rebuild.Read the rest of Building my own balun, part 5: First tests of the result