I have had some issues with aiming the antenna as the feedback from the G-5600B has been very flaky – I found out that it’s very likely [...]]]> I decided to put the antennas up and take part in the ARRL contest as the WX forecast was good – specially so late in the winter.

I have had some issues with aiming the antenna as the feedback from the G-5600B has been very flaky – I found out that it’s very likely a dirty pot in the back of the control unit. Then my beloved amp blew a fuse .

I’m hearing quite well – but sometimes it’s like people dont hear me!

I’m sad to have missed Japan and other Asia stations – but I have houses obstructing the east path to the moonrise! Now there is a clear plan forming to try to get VK/ZL/JA in the 2m EME log! I might have to wait for the moon to be in a northern declination – and perhaps move my QTH temporarily.

From my current QTH I dont see the moon from about 280° – 0 – 80° – and I always have to have at least 6° elevation.

update: Thank you for all your patience ! this was really fun – just under 100 QSO’s total in this try!

All QSO’s logged here on this page: http://www.tf3cy.is/eme-qso

73, Benni TF3CY

So I have been having big problems trying to get a pre-amp working inline.

The problem is that it has to be sequenced in and out correctly. Then the grand plan was to introduce a big linear amplifier into the equation.

I had several issues – I had no good relays, except [...]]]> Hi all

So I have been having big problems trying to get a pre-amp working inline.

The problem is that it has to be sequenced in and out correctly. Then the grand plan was to introduce a big linear amplifier into the equation.

I had several issues – I had no good relays, except for some big 24AC relays I bought by mistake on Ebay. Budget does not allow some cool vacuum relays – so I decided I would use what I have.

As I’m pretty lousy in designing proper DC circuits – I decided to use a project that was already underway, my Amplifier + rotor controller + sequencer that I have been working on. I had already put a vero bord into a small chassis and hooked a LCD + rotary encoder + some push-buttons. I even had some 7 port darlinton relay drivers on hand.

So toady I have put the relay into the chassis – built a relay buffer -with some relays to switch on 28V AC going into the BIG RF relays (not really RF relays) and gotten everything to work.

This is mainly because I use a small board called Teensy2++ – that houses a really powerful Atmega microcontroller. It has numerous in and out ports – 8 A/D converters and runs on 16Mhz – so you can be really sloppy programming it – wont notice it to much. And the best part is the bootloader that comes with the teensy – you have a small program running – it will detect when you press the reset button on the teensy and upload a new code in 1-2s via USB. This is so much faster than ANY ICSP programmer I have tried and is perfect for someone like me. trial and error!

So I could just plow through writing the sequencer code upon my “testbed” with the LCD and everything hooked up. So now I have a working sequencer.

Only really bad hack was to intercept the PTT line from Signalink USB to the Kenwood. Time was short – I did a ugly thing… look at the picture. Probably have to order a new cable from Signalink.

Here are some pictures – This will hopefully be finished some day – preamp is working – now just the big test – try to xmit!

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As I needed [...]]]>

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:

• Input voltage: 220-240V (jumpable)
• Output voltage: 4x 28v
• Output current: 4x 25A max (limited at 23A)
• Maximium power rating: 3KW
• based on 723 voltage regulator + 20x 2n3055 output transistors.
• 150ms slow start is accomplished using control from a PIC 16F877A microcontroller. (using 10Ohm resistor)
• LCD display that shows current and voltage per channel and cuts out the PA and Power supply if over voltage or over current status is detected. It’s bit slow as the processor is running at 5Mhz so the reaction time is around 10ms.

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 :

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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:

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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.

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 [...]]]> 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:

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here is a screenshot FROM Rod ZL3NW:

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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

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 – [...]]]> 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.