py500A question

kathodyne · 3rd February 2006, 02:43 AM

been using them for almost a year now, and they perform great.....
but lately i discovered that -as it seems- there is a second getter forming (or the getter material is moving)
the area on the glass around/under the top-cap (cathode), now almost looks like a getter.....i can still see through it with a little difficulty....

the normal getter (on the vertical side of the glass) doesn't seem to have shrunk.....

i assume this is normal, but have found nothing to read.....
any comments???

Tubes4e4 · 3rd February 2006, 05:16 AM

Hi kathodyne,

I have seen this effect with PY500A which saw lots of years of service. I cannot comment if this means trouble or not.

Tom

richwalters · 3rd February 2006, 07:13 PM

Same effect noticed.... the internal impression is a bit unsightly as you remarked...I've been using several sets of NOS ex MiL CV 2975 (EL84) for 10 years in my amp without problems. These are mean't to be bomb proofed. time-to-be-served tubes and so on goes the jargon.....I hope so. They are remarkably settled and stable, indictative of NOS.

richj

3rd February 2006, 02:43 AM	#1
kathodyne diyAudio Member Join Date: Feb 2005 Location: leeuwarden, netherlands	py500A question been using them for almost a year now, and they perform great..... but lately i discovered that -as it seems- there is a second getter forming (or the getter material is moving) the area on the glass around/under the top-cap (cathode), now almost looks like a getter.....i can still see through it with a little difficulty.... the normal getter (on the vertical side of the glass) doesn't seem to have shrunk..... i assume this is normal, but have found nothing to read..... any comments??? __________________ emission over emittor

3rd February 2006, 05:16 AM	#2
Tubes4e4 diyAudio Member Join Date: Jul 2005 Location: Leverkusen	Re: py500A question Hi kathodyne, I have seen this effect with PY500A which saw lots of years of service. I cannot comment if this means trouble or not. Tom __________________ If in doubt, just measure.

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3rd February 2006, 07:13 PM	#3
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	Same effect noticed.... the internal impression is a bit unsightly as you remarked...I've been using several sets of NOS ex MiL CV 2975 (EL84) for 10 years in my amp without problems. These are mean't to be bomb proofed. time-to-be-served tubes and so on goes the jargon.....I hope so. They are remarkably settled and stable, indictative of NOS. richj

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