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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 10th Apr 2021, 6:25 am   #1
Robert Gribnau
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Default Does the EF88 really exist?

Is there a forum member that actually saw an EF88 and/or has more information on this valve type?

As far as I know, the EF88 is only mentioned in “A Comprehensive Valve Guide, Book 3” (Babani, 1960) and in later editions (atleast from 1963 going) of the “Electronic Tube Handbook” (Muiderkring).

On Radiomuseum.org the EF88 has its own page, but I suspect this to be the result of the EF88 being mentionend in the Muiderkring handbook since the diagram for the EF88 comes from that handbook. The diagram does not show more information than de Babani guide does. Probably Muiderkring based their diagram on the data from the Babani guide.

https://www.radiomuseum.org/tubes/tube_ef88.html

On first sight it appears that there is some more info, like the pin-out diagram from a Telefunken handbook and a picture of the bottom side of the valve. But I could not find the EF88 in any Telefunken or Siemens handbook (but ofcourse I don't have acces to all their handbooks), so I suspect Radiomuseum.org used the pin-out diagram of the EF86 (or an other pentode with identical pin-out). And since the same picture of the bottom side of a Noval valve is also used on some pages of other Noval valves (mostly in cases where an actual picture of the valve type is not available) it is probably not a picture of the bottom side of an EF88.

The E88F surely does exist, but that is an EF80 intended to be used with an Noval to Loctal-8 adapter (the Philips/Mullard factory code on that E88F is identical to the factory code of the EF80). Since the pin-out and most of the other data of the EF80 are very different than that of the EF88, there seems to be no connection between the EF88 and the E88F (like for instance there is no connection between the EL81 and the E81L).

https://www.radiomuseum.org/tubes/tube_e88f.html

So to me the EF88 is a mistery. I never even saw a picture of one, let alone a datasheet with curves.
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Last edited by Robert Gribnau; 10th Apr 2021 at 6:33 am.
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Old 10th Apr 2021, 6:49 am   #2
Electronpusher0
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Default Re: Does the EF88 really exist?

Martin Forsberg has (with Megger's permission) produced an OCR version of the AVO valve data manual 23rd edition.

The EF88 is listed in there.


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Old 10th Apr 2021, 8:13 am   #3
Julesomega
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Default Re: Does the EF88 really exist?

You have to wonder if it was a copyright trap, like Agloe or Trap Street
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Old 10th Apr 2021, 8:50 am   #4
Robert Gribnau
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Default Re: Does the EF88 really exist?

The AVO valve data manual contains the same (but not more) info on the EF88 as the Babani guide and Muiderkring handbook.

I did look at the data on the E80F, EF83, EF86, EF87 and EF806S since they have the same pin-out as the EF88, but none of them seem to match with the data of the EF88.
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Last edited by Robert Gribnau; 10th Apr 2021 at 9:03 am. Reason: Correction (language) & Addition of EF806S
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