In 1983-1984 a lot of hard work was spent trying to combine rf power from four PA with HT323 tube (equivalent of 2C39) acquired from old 2 GHz MW link (Rafena, DDR ). Finally in 1984 we peaked up to 100W rf and got the first EME echoes on 13cm. In the first sked on 5th May 1984 we succeeded with OE9XXI. At that time there were QRV on 13cm EME just several EME stations from EU and a few from the US. The memorable one was Paul Wilson, W4HHK. We spent huge time repeatedly trying with Paul without QSO completion on his side. We heard him almost every sked from T to O signal but our signal was weaker at Paul. It was hard long procedure because each one sked was arranged via post letters! However, when Paul jumped over 18m of low loss coax by moving antenna relay and LNA to the focus of 5.5m dish, the 37th sked on 10th February 1989 was finally the success with O/M reports. The next day we completed easy with 549/O reports (details in the 13cm LOG)
To get more stable and higher rf power we replaced in 1987 forced air cooling for liquid cooling. The liquid used was light tranformer oil (anode voltage 1400 V). Distilled water was out of chance due to frost inside the shelf during winter.
Liquid cooled 13cm PA was used up to 2002 when the floods destroyed most of the old EME rig and our history HW went into scrap. However this PA supplied 122 QSOs, 41 different stations from 19 DXCC. The last one was with F2TU on 24th March 2002.