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Hi_Q 30th April 2010 03:02 PM

Sagging Heaters
Having had some EH 6CA7's in operation for some months I noticed that their glow became significantly less as weeks rolled on. The cathodes still appear to be as red as ever it is just that the heaters no longer show their heads above the cathode and subsequently appear dimmer. They have physically dropped down inside the cathode tube. Is this normal for the 6CA7 or should I start looking for another manufacturing source? Strange really that one still has a healthy glow at the top whilst the other three have a brighter glow at the bottom.

BTW the heater voltages are correct at 6.3V

kevinkr 30th April 2010 05:22 PM

That's an interesting observation, and not something I have seen in anything I am using. I would check to make sure that if that progression continues the filament wires are not going to come in contact with an electrode connection..

You might also want to share your observations with the original vendor.

I'm not quite sure what to suggest, but you might want to get a set of replacements in the near future and in the mean time continue to monitor the situation to make sure the sagging/slipping has or hasn't stopped.

Replacement is obviously the safest most conservative option but might not even be required - they may have slipped as far as they are going to and might be just fine going forward. Alternatively they may continue to slip/sag and the filaments open up over time or worse short to something they shouldn't.

It's a judgement call, but were it me I would replace them with something else and ask for my money back. This obviously shouldn't be happening.

exurbia 30th April 2010 05:32 PM

My missus has the same problem :joker:

Trebla 30th April 2010 10:47 PM


My missus has the same problem
Heaters.....not hooters. tut tut.

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