I passed my novice radio amateur exam in March 2013 and I registered the
PD4KH (pappa delta four kilo hotel!).
I passed my full radio amateur exam in March 2016 and I registered the callsign
PE4KH (pappa echo four kilo hotel!).
PE4KH on qrz.com
I am usually located around maidenhead locator: JO22NC
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.
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:All 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.
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.
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.
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.
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.
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.
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.
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.
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.