sobota, 31 sierpnia 2013

Test of mobile setup...

Due to many business trips that I have to do I usually take some radios/antennas etc with me. This time I decided to test small linear PA with FT817. The problem was a power supply because with over 100W power output the required current is over 15..20A. It is too much for cigarete lighter socket in the car (usually limited to 10A). Taking 30kg 107Ah battery for business trip is not too convinient. Connecting car battery requires long and thick cables and some efforts to assemble and disassemble everything.
I tried the solution with LiPo RC planes battery. It doesnt have too much capacity (2..3Ah) however may give high current without significant voltage drop. It cannot be used for a full day of dxing but for a few QSOs should be absolutely enough (and this is my case). Additionally this battery can be charged with time less than an hour (15..20 minutes in extreme cases) and is very small and light (used in models of planes). The disadvantage is that it requires special equipement for charging, may be dangerous if charged/discharged not properly (becomes a flamethrower), is rather delicate and needs constant monitoring of all the cells (if the voltage drops below around 3V per cell may be damaged).

I did the tests somewhere in Alsace (France) on a highway parking.. It looked like this here:

And the setup looked like this:

And the elements on the picture above are:
1. radio (Yaesu FT-817)
2. LDG autotuner z11
3. linear PA (modified from CB PA)
4. LiPo battery, 2.5Ah, abount 12 V
5. Battery tester monitoring voltage of every cell
6. Turnigy wattmeter measuring voltage, current, used capacity etc
7. food/drinks for the operator (doesnt look really healthy..)

This setup seemed to work well and the voltage was not going down even with full power on CW. I dont know how many QSO it may be done on one battery but this test will come soon.

The yellow connectors used are XT60 connectors used in RC model technology (there is a separate post about them I guess).

środa, 17 lipca 2013

IARU 2013 - picts

IARU 2013 is over... 
As every year months of preparations, constant station improvements finished with one very busy weekend in July... 
This year there were two main changes to my station configuration:
1. rotator for the antenna
2. when rotator is used it is good to have computer which calculates the bearings... computer is also very useful for other contest activities (logging, checking, playing games during storms..) So the decision was that computer will be also involved (hurrraaayy, no more paper dupesheets!!!)

My farmer (Herr Meyer) agreed to use his field as base for my contest activities (maaany thanks Herr Meyer!!!). My wife baked some cakes so both side were happy :) This time the field available was on the top of the hill and my impression is that the conditions were better then when I used the field in the valley. 

As year ago I resigned from building the tent. It takes too much time to build the tent and then to put it back to the bag. Additionally if it is raining it is a problem later to get it dry. 24 hours in the car is not that bad...

Following last year experience (started station building around 18:00 on the day before and was delayed with contest start for around an hour) this year I started much ealier - around 14:00 (2pm) on Friday. Thanks to this I started contest... with one hour delay... Maybe the reason was the changes I introduced in my GP antenna just before the contest. I thought it will take several minutes but that was definitely longer. Maybe next year I will start on time (that would be probably the first time). 

This rotator and computer changed the requirements for power. Radio alone on QRP power even with Panadapter is ok on two car batteries (my car has two). After 24 hours you can still start a car and go home. 

According to my calculations with computer and rotator I may need between 100 and 130Ah (for 24h contest). It doesn't include light and other car equipment. I was afraid that after such power consumption I may have problem to start a car - the batteries are 7 years old and don't like to be deeply discharged. For a while I wanted to buy a power generator (planned since ever) but the version I want is still to expensive. Finally I decided to get a additional battery - 12V 107Ah AGM type battery designed for solar installations and electric wheelchairs (can survive deep discharge). So finally I had almost 270Ah onboard which appeared later as more than enough.

Just before I ensured that all my three baterries are fully charged. 

niedziela, 12 maja 2013

IARU 2013 preparations started...

Like every year more or less this time I start to think about this year contest. Last year I had the best result ever and even was listed in official results (in NON-W/VE list) but the goal is TOP-TEN and possibly close to rather "TOP" than "TEN". It is probably many things that I could do better and have better score but I have no idea which they are :)

This year the improvements to my station setups will be at least: 1. rotator for the antenna - no more running to tower with wrench in my hand to rotate it manually... The rotator is just on the way and I expect it next week here. There are some works necessary to adapt the mast to rotator. And again I have no idea how to erect mast which this year will be even higher (plus rotator height) by one person to 15 meters height.

2. I was thinking about power generator but seems to be too expensive so far. Maybe I will consider some cheap one just for battery charging but cheap is usually enemy of "good". Luckily the rotator is powered from 12V. Maybe I will find somewhere some notebook with limited power consumption so I will have computerised station again. The advantage would be using computer for steering the rotator with automatic azimuth finding...

3. 40/80/160 meters antenna.. this is usually weak side of my station. Spiderbeam does not cover these bands so I use primitive GP antenna from 18m fiberglass mast. I have impression that it doesn't work as it should and looking for some plans for antenna based on such mast. Do you have any??
4. less sleep work more. Yes, I know - no sleep during contest. I will try this way in 2014.. maybe..

Hope the farmer, that is so kind that lets me use his field for my station will allow this this year as well. Every year my wife bakes some cookies for him. Hope he likes them :))

Seems I havent been publishing anything here for "some time". I will try to do my best to improve this.

sobota, 19 stycznia 2013

IARU HF Championship 2012 - Results

Just published...
Looks like around 30.000 points is maximum what I can achieve from current setup. Need to consider how to double it to be always member of TOP TEN :)