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I decided to jump the gun as the weather is so good now… I put up a 2m5WL yagi, have to have it vertical polarized. I have a view from ca 100° east to 250° – Got az/el control. Having issues getting the pre-amp inline and the power amp to work togeather. coax is from “cable experts”.
I needed a power amplifier for 6m EmE, so after looking around I found that my father TF3T had 4 unassembled AR313 kits from Communication concepts lying around, he also had a PCS4 splitter/combiner. This he bought some 15 years ago. They are based on the MRF141G “gemini” tranisistor. http://www.communication-concepts.com/ar313.htm As I needed QRO asap this summer, I decided to build two modules and combine them with a combiner I already had. Also I did not have a powersupply to drive 4 modules at the time. The amp was built and worked well on 6m. It was not until this winter I got interrested in 2m EmE, the plan was changed and now I would get the amp working on 2m as well. This really just meant building a small relay board to switch between two low pass filters. Power supply: basic specifications:
So basically this is a 3KW linear power supply built around a 3KVA toroidal transformer woven by Airlink transformers (UK based). It’s a heavy transformer, 17Kg and I got it delivered to Newcastle where I was on a business trip, bought a small cabin-case for it and took it through BA flight to London and then to Iceland. There is a loophole in the on-board luggage rules at BA, only dimensions, no weight restrictions. As the power amplifier has 4 PA modules, each operating at 28v/22A I decided it would be easier to build the power supply with 4x 20A outputs, rather than 1x 80A output. I’m using the standard 723 regulator with a 2n3055 in a Darlington pair configuration, 1 driver and 5 bypassing. The PSU has a slow start using a relay that shorts a 10 Ohm after around 200ms The PSU is controlled by a PIC control board that uses it’s 8 AD inputs to monitor voltage and current. I use a PIC 16F877A as I just happened to have few lying around. Current is measured using a standard op amp in a differential configuration. I decided to use a inductor on the output and use the resistance in the 16AWG wire as the shunt, both for current sense and current limitation. for now, here are some pictures, I will update this later perhaps with schematics if someone is interested : The amp is based on the AR313 . I have already the amp working at 600W, but I’m adding two more modules to give a combined power of 1200W. here are pictures of the current work: It’s not pretty, but in tests it puts out 1200W on 6m. I don’t have the ability to fully drive the amp on 2m , but it’s going up to 600W, but I see it’s not very efficient on 2m – that worries me. The 2m low-pass filter can been seen there in the back, it uses RG142 coax cable as capacitors, close to 1pF per 1cm, so each of the capacitors is 18cm of RG142. It was modelled in Elsie, and used a miniVNA analizer to test it. The amp is being built from the ugly design of my first 600w 6m amp, so I look at this as a test bed for the moment. I have a nice chassis that I want to mount the amp in later. I’m also working on a nice sequencer to control relays and the pre-amp. That is coming – but I think I will test the amp on some nice EME over xmas. update: 22/12/2010: Tested the amplifier on 6m – 1200W without saturation, can overdrive to 1500W. Power supply heats up well and after a 50 second xmit the transistors are cool, only thing worrying me is the 30 ohm balancing resistors are heating up -(50-60°C). Luckily I have 10x 25ohm 50W on it’s way from ebay (russian made). I could only drive the amplifier up to 200W on 2m but the Yaesu 723R is just to weak to drive the amp, I need around 40W on 6m to fully drive the amp, but I only get about 6w to the amp due to some mismatch in the splitter on 2m. Very nice beam, sorry for the poor picture, only from the mobile phone. We had a wonderful time at the Island. We where welcomed by the lovely people that live in Grímsey. We will definitely visit the island later on, perhaps during the IOTA weekend next summer. I made some 600 contacts, mostly on 20m SSB, some on 10m. We had some heavy aurora activity over the weekend so fewer contacts where made on the lower bands. TF3SG still made some contacts, and one JA QSO was made on 80m. Conditions where strange on 10m. Had a big opening into Spain and Portugal, but going over my log I see that I logged a single QSO with Trinidad and Tobacco on 10m I did not notice that when I made the QSO, would be fun so see that confirmed. I did not hear any US station though. I was just using the 43ft vertical with a tuner, so not a very efficient antenna for 10m. 73, Benni TF3CY I’m now on a mini-dxexpedition to Grímsey, it’s right on the Artic circle, 66°N. I’m here with my brother, TF3SG and father TF3T. We will be QRV on 20m thorugh 160m. I will post some pictures if my internet connection stays on. We are slow moving, trying to work the pile-up’s Okay, after making a fool out of my self for few times, I called my fellow ham TF3HZ and asked about the reporting exchange used in JT65A on HF. He talked about “right-clicking” in WSJT, and then everything made sense. Now on a JT65A “RUN” fun but slow ! I’m using 20w into a 43ft vertical with a small tuner at the base. It has very poor ground, but I have been thinking off pulling back on power as my reports are usually around -10. I hope I’m being a good op, as I don’t send a final 73, I usually go into CQ TF3CY after getting a 73 from the caller. I think it’s more efficient (not very amateur’ish) as I will not lose a whole 2 min. I have been killing time while at work, so if I just dissapear from the spectrum, it usually means that I have to do some actual work! 73, TF3CY happy hunting Any hams looking for QSL cards from me, don’t worry you will get them. I had to print a new card, and well, very busy summer and been away from home almost 2-3 months. I raised a 40ft vertical in the garden with very poor ground radial system, put a small tuner at the base, let my wife key the transceiver while on the phone, and tuned. The tuner was set on a target freqency on 80m, after trying some SSB phone CQ’s wihout anyone answering, I decided to try JT65A. No luck on 80. But I tuned the rig to 20m, and there where some real good signals, at least nothing like the EmE signals. Pressed AutoTune – and it would actually tune. I guess I was perhaps getting few milliwats out, as I was using two tuners in a row, and one was trying to match a vertical on 80m But I got confused.. everyone is sending signal reports, and I tried one QSO and gave OOO as report. Not sure if that was correct – anyhow, we did not finish the QSO. sorry N9GUE got your R-16 but JT65a is amazing – or I should have expected it – as I have been using it for EmE. These where huge signals compaired to the faint traces I have been trying to decode. I’m pretty sure I made the first 6m contact from Iceland to New Zeland! After not having completed one QSO using the portable EmE setup, I was thrilled to compleate 3 QSO’s when the moon was between 7 to 3° this evening. First QSO was with Mick, W1JJ that I had already worked, but that confirmed that the homebuilt amplifier and antenna was working. Also this was the first QSO on the current transceiver, small but nimble Kenwood TS-570D. I had a sked with K6QXY and I copied him very well and the QSO was over in 3 minutes. I started calling CQ and in the next sequence I got a decode from Rod, ZL3NW!!. We finished the QSO quite quickly. I don’t know how do descibe it, thrilled does not even come close. Strange, sitting in a ice cold van in the middle of nowhere, watching a computer screen feeling this excited! I’m going to try to get EX6EME next morning, then use the evening to try to complete more QSO’s! here are some pictures of the current setup: here is a screenshot FROM Rod ZL3NW: Locator is approx HP84xd or HP84xc. Will be running 600W using the 10el beam. I would like to work as many stations as possible, so please email me I can only work the moonset – so fire up GJTracker and see if you can work me. 73 de TF3CY I have gotten few emails asking for sked’s on 6m eme. As my current working conditions are uhm… none – I can’t have a fixed EmE installation at my QTH. So I have this portable setup that I plan to use when I have good conditions. Good conditions mean of course low degradation – but also as I live on the south-west coast of Iceland, I would like to be able to see the open horizon. So any azimuth to the south-to west would be great – my grid square is HP94 so that will give you some idea how to work me. I will be trying to find a location I can leave the antenna over night, so I will perhaps 3 days I can work the moon. I will be QRO soon – I’m still waiting for the experimental licence as our normal general class only allows 100W RF. I have asked the PTT to be able to transmit 1Kw RF, hopefully that will be granted. I have a 1200W solid state amplifier I’we nearly built and will be tested in the next days. so please email me if you want to arrange a sked email is benedikt@ccpgames.com I’m going to try to work as many good “windows” as possible this summer. Next window I’m looking at is around 12 August – then the moon will be in a good position for me to work the low elevation with good degradation. |
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