Category Archives: Ham radio

Back on HF – now remote

As I live in the city, space for antennas is limited, specially for the lower bands like 40-80-160

I have been trying to find a solution for this problem. I work for Vodafone in Iceland, I found out that we have a transmitter site just outside of Reykjavik – about 20km direct line from my home QTH.

The transmitter site has a 50m high tower for cellular and TV/FM broadcasting. Small house and good connectivity to the internet.

I asked around and got a yes from the persons running the site for putting a small “half rack” of equipment into the transmitter site. Antennas must be outside of the actual site. 

The area is quite close to the city dumping grounds so it’s not really prime real estate. Next thing I needed was permission from the City for the antennas. I managed to land a provisional licence for antennas just for one year at a time. I’m working on getting a more permanent licence, but as the area is not planned for any development I don’t foresee any issues getting the licence prolonged. 

But the takeoff to the west is amazing, it’s has sloping grounds towards the sea. 5 Km to the north is Esja, a 1km high mountain ridge, so that limits the takeoff to about 10-12¬į – Should be fine.

I started building everything I need while I waited for the licences process.

Using  a K3 with RemoteRig RRC controller

Amplifier is homebuilt SSPA – remote operated

Relay control is Raspberry Pi – with home written code

Everything else is homebuilt

Plan for 2018 is the following

40m rotary dipole

80m 4Square

160m Inverted-L or some vertical variant – using the Vodafone 50m tower for support

73 de TF3T

Current project – 2m amplifier using a BLF188XR

I decided to abandon my GS35B project, manly due to lack of drive power … from my current exciter. I was originally going to build a 200w SSPA just to drive the GS35b amplifer, that was getting very complex – no access to 20A of 28v for the kit I had.. so I decided to jump on the Freescale/NXP design everyone is talking about. I turned to Jim W6PQL for parts!

Project is coming along – must finish – must get EME antennas up!!

.. when I finish the amplifier I will post some more pictures.

 

73, Benni TF3CY

TF1CY in CQ WPX 2012

Fun contest, but as I had to work all Friday I rushed to the summer house late Friday, raised the 22m high vertical and assembled the th7dx. Then it was dark and I finished connecting everything and tune out on 80m. I started the contest on 80m but I was then just to tired to continue throughout the night. I woke up early and finished getting the Th7dx mounted and raised the antenna. I got into a sticky situation when I forgot a u-clamp in the last taper section of the mast just under the rotor. The mast was bent there and I was very scared of losing the antenna. I got my brother (TF3SG) to come to my rescue – we lowered the antenna and after inspecting the tubing and installing the clamp we raised the antenna again and proper guy’s.

Conditions on 15m where hard and I kept losing my running freq. I tried few times to move to 20m but the QRM was just to much. I went back to 15. Sunday was better on 20m – and I got to around 800 contacts. I was not being heard well on 40m (tuning into the quarter wave intended for 80m). ¬†I decided to go to 80m and I found a nice clean frequency and got a nice run ¬†mostly EU but with handful of VE/W – I ended there with 1005 QSO’s.

 

73, Benni TF3CY / TF1CY

 

QRV in the ARRL contest 19-20 nov

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¬į – 0 – 80¬į – and I always have to have at least 6¬į 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

1200W 6m – 2m power amplifier based on the motorola AR313

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 :

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. ūüėČ

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¬įC). 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.

End of a very nice stay in Grímsey.

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

Grímsey Active now EU-168 IP06XN

I’m now on a mini-dxexpedition to Gr√≠msey, it’s right on the Artic circle, 66¬įN.

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 ūüėČ