Hi to all guys here. Have a ECL84 (Triode pentode) in a circuit like a µ-Follower but triode over pentode. After warm up it starts to arcing between triode plate and pentode cathode (also suppressor and internal shield)near the lower mica insulator; between them there are about 1 mm separation. The voltage gradient between both is about 275VDC. Data sheets I consulted don't specificate this maximum rating.
Is the tube defective or overloaded?
Thanks to all opinions‼
Is the tube defective or overloaded?
Thanks to all opinions‼
Attachments
Hi Osvaldo,
sounds quite strange, I would assume a defective tube if everything is wired correctly. I use the PCL84 (same system with 300 mA-heaters) as driver tubes in a KT150 PP-amp, and the pentodes are pushed quite close to their 4 W plate dissipation with about 230 - 240 V plate voltage - first set of KT150s has burnt out in the meantime, but the PCLs are still fine.
But when switching both systems in series, watch for not to exceed heater insulation voltage, especially with "E"-tubes..... "P"-heater tubes have often a more rugged heater insulation.
all the best
Uli
sounds quite strange, I would assume a defective tube if everything is wired correctly. I use the PCL84 (same system with 300 mA-heaters) as driver tubes in a KT150 PP-amp, and the pentodes are pushed quite close to their 4 W plate dissipation with about 230 - 240 V plate voltage - first set of KT150s has burnt out in the meantime, but the PCLs are still fine.
But when switching both systems in series, watch for not to exceed heater insulation voltage, especially with "E"-tubes..... "P"-heater tubes have often a more rugged heater insulation.
all the best
Uli
- Status
- Not open for further replies.