I just arrived back from the holliday. It’s now a week that i’m back home and chasing dx again.
During the week i’ve worked St0R 18 times. Also ZD8D and Ty1KS are in the log.
During the transmission everything was ok. The installation looks normal. After i’ve worked a a few dx i did listen and updated my log.
But what happend all of a sudden. Then the power went down. All dark in just a few seconds.
I did go to the power fuse and enabled the power again. Everything looks normal. I did check the power cords and all seems to be ok.
i did siwtch on the Amplifier again and also this was working fine again. Output ok. No idea what the problem was.
Well until last night. The power went down again for the second time.
I switched on the power fuse again and tested the installation. Now i had a hugh failure. The Grid of my Alpha9500 was high and siwtched of in protect mode.
That is not a good sign. I’ve called a friend and told him the story. Oh he said bad luck you have a Grid flashover.
I’ve ask him what do ya mean. It means your tube is gone.
Normal a tube would live for over 20.000 hours. Mine just broke down in 2 years time. Is it normal or just bad luck.
I’ve searched on the internet. And found prices of the tube. 1300 dollar for a new 3xc1500 at Rfconcepts.
Lucky i did get good infomation to get the tube for a much better price. Lets hope the Amplifier will be online again very soon.
16 august 2011. A small update
Today we recieved the Tubes. Very nice new tubes bu DK3EE. They are not the 3cx1500 but the 3cpx1500 tube . Much better in quality. Ok this morning i had time to change the tube in the Almpifier. After that i tested the Amp on the 1kw dummy load. Again without a good result. High grid and direct in the protect mode. I was allready in contact with Rfconcepts. They told me a complete differend story. They where sure i had a arc in the grid circuit. I could not believe this because the 220v in the netherlands is very stable. In fact they where correct that its not the tube. So we both have to look futher to see what the problem is. Tobecontinued.
20 september 2011. Update 2
I did recieve on the 20th the controlboard back from Alpha. They repaired a few components on the control board. At first i wanted to test the Amplifier with the orginal tube. At first everything looked ok. But after 4 hours my power breaker went down. All in the dark. Hmmm . After a few time i opent the power breaker. The contacts where complete black. So i replaced it 2 times. First i did try a B16 and later on a B25. 25 amp could go true. Both the power breakers could not hold the line. It was kinda late and needed to get some sleep. Lets wait till tommorow if i can come up with a plane.
21 september 2011 (Next)
And i did. At first i changed the tube of the Amplifier. I replaced the 3CX1500 Eimac for a 3CPX1500 Eimac. I really had the idea it was a flashover after all. I took a power cord and did switch the Amplifier on to a complete seperate power breaker. It’s now 5 hours later and still the Amplifier is online and the power breaker stays online.
My conclusion. The Amplifier did get a Flashover in the tube. My power breakers could not hold the line and switched off after a few hours. The falshover caused a power surge on the controlboard that needed to be repaired.
To obtain maximum life from an 8877:
Do not cycle the heater excessively
Do not run more than 50 mA peak grid current
Do not exceed 150 mA grid current even for very brief periods
Do not apply HV or draw cathode current unless the heater has been within the factory specified range for 3 full minutes. If you start the heater very slow you need a
Never run the tube when heater voltage is too low. Doing so will poison the cathode
Tags: Alpha9500 Anode, dx, holliday