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).