Optical contact between OM1LD and OM3Kii over 94km

6km before the 100km border. We need to find suitable places with longer distance.

On October 2-nd 2009 we made radioamateur optical contact on red line (650nm / 461THz) between OM3Kii and OM1LD. The contact distance was 94km. Materials with path information were provided before the contact. It was 6km before the 100km border. We need to find suitable places with longer distance.

Story from Robo OM1LD

Station	Participants	QTH	RX	TX
OM3Kii	Rado OM2ZZ Roman OM3EI Stanka OM8AQ	JN88UU (Velka Javorina, 965m ASL)	150mm lens, focus 220mm oboR RX design	Laser diode 60mW 650nm (461THz) AM / CW
OM1LD	Robo OM1LD	JN88QA (Near Samorin, ?m ASL)	74mm Lens oboR RX design	Laser diode 10mW 650nm (461THz) CW

Story

We (Robo OM1LD and me) decided to try our next optical contact day before the UHF contest. On friday morning it seemed the weather is OK and visibility is standard. But in the evening the visibility changet to aproximately only 40km. We were sure it can not work, thereforewe wanted to spend the minimum time on the hill during the optical tests, because there were pretty cold. Fortunately, spot light from Samorin was visible, even mist, so we stayed on the hill 3 hours. At the begining we were not able to setup our lasers correctly, so signal from Robo was very weak. We made our first contact over the 94km two way CW. After the CW contact we tried to aim our lasers once again and we were succesful. Signal from Robo was quite strong for his 10mW laser. The second contact we made AM / CW.

After the contact we tried simple spotlight (1W green LED and narrow lens), but we were not succesful. Green LED needs better optics. Mr. Murphy was with us once again - my recording device (MP3 player) failed again. So I do have only one recorded audio - from the second laser aiming.

Well we are pretty close to 100km border, we arelooking for the suitable places for our next longer contact. Sometimes it is noteasy job, because - we tried optical contact from Velka Javorina to Samorin in 2007. The path seemed to be same, but we failed. Robo found that in our path was hill - obstacle in 40km. Now I mooved to the other side of the hill, obstacle - hill was close, but the optical contacts worked OK.

Recorded audio - OM1LD over the 94km optical path.

Knowledge

1/ It is essential to know the exact location of the oposite station

2/ Good spotlight is necessity

3/ I need to improve my audirecording device

4/ Robo needs to improve his TX power

5/ Far optical contacts are possible with good colimated optics over the bad weather (haze, water in the air)