81km Radioamateur Optical contact OM3Kii - OK2KQQ/P

On August 31-st 2009 we made radioamateur optical contact on red line (650nm / 461THz) between OM3Kii and OK2KQQ/p. The contact distance was 81km. Materials with path information were provided before the contact.

Story from Robo OM1LD

Story from Boris OK2QW

Story

The solid weather at the end of the august was a promise of the next optical contacts. we decided to try it on the monday 31-st august 2009. We (Vlado and I) were on the hill at 15:00 CET We wanted to tune 7MHz inverted Vee antena for Vlado, to compare antennas for 23cm and 2 meters for Vlado and cut the support ropes for tube mast for me. We finished with work at about 19:15 when Robo came to the hill too. We setup our equipments and waited for the sunset. Comunication link was on 145.425 with handys on both sides. We started our optical beacons before the sunset. Boys on Radhost saw us, so they pointing to us with their laser. After a while we saw a the red laser from Radhost. So we started to pointing our lasers to the Radhost too. The contact could start. Mr. Murphy were with us - my recording software failed, and notebook frozen. I tried to fix it and restart the notebook several times, but without success. Anyway in this modern era we do have mobile phones with sound recorder, so I recorded my next contacts with mobile phone. 

First we made contact as a radioclubs OM3Kii and OK2KQQ/p two way CW, next we tried it on AM but OK2KQQ/p was able to transmitt only CW so the contacts were made cross mode.Later we made contact with our personal callsigns, so small pile of contacts were made. After the successful contacts we tried to make contact with 3W LED CW TX. Boys on Radhost saw the red light, but their receiver was silent. So we were not able to make noncoherent contact over 81km distance. We compared our optical beacons and results were as we expected. Robo have 20W xenon light with objective and I have 50W halogen lamp with 4 deg angle. The xenon was two times stronger and it was "sharp" green ligth. My halogen was weaker with yellow warm light. Both beacons were usable for contact over 81km distance. Finally we took some night photoes and left the hill with good feeling.

I would like to congratulate to Boris to his excelent solid signal from Radhost. The more power is necessity for optical DX contacts. 

Knowledge

1/ Lights from TV tower are not sufficient as a search light. The optical beacon is strongly recomended for the longer contacts.

2/ Both sides needs optical beacon.

3/ 20W xenon light is better than 50W halogen over 81km distance

4/ Light from 50W halogen lamp pointed to near tree was visible over the 81km distance 

5/ For longer contacts we need better 2m equipments (more power and bigger antenna)

6/ We need to buy precise compass for exact azimuth finding

7/ We need to improve our receivers

Recorded audio during the QSO with OK2KQQ/p  (wav - 3MB)

Recorded audio during the QSO with OK2SS        (wav - 6MB)

Photo album

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