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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 26th Nov 2020, 11:14 am   #1
GMB
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Default Valve equivalents - electrically

There are loads of valve equivalent lists around, i.e. different numbers for either the exact same thing or something close.

I have noticed people making comments like XXXX valve was effectively the same as the old YYYY valve but in a modern envelope.

But does anyone know of lists of valves that are not plug-compatible but are effectively the same thing?

As much older valves become scarce, it would be useful to know that one can substitute it using a particular "modern" valve using a suitable adapter.

Are there also lists of the exact same valve but with a different heater? Sometimes this is easy to guess - but not always.
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Old 26th Nov 2020, 11:21 am   #2
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Default Re: Valve eqivalents - electrically

Id be interested to know this, but I suspect it comes down to studying data sheets with a few valves in mind.

I'm lazy and often just look for drop in replacements, and for that I use the rtype web site which shows list of "sensible equivalents", then take a look on ebay or whatever...
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Old 26th Nov 2020, 2:22 pm   #3
G6Tanuki
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Default Re: Valve equivalents - electrically

It's an interesting question: you get things like the EL41 and UL41 which you'd _think_ were the same innards with different heater-voltages, but the published figures don't necessarily bear this out.

There are also oddities - I've seen a version of the 6V6 with a 300mA heater rather than the usual 450mA - it was apparently used in some US TV sets.
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Old 26th Nov 2020, 2:34 pm   #4
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Default Re: Valve equivalents - electrically

EF6 - EF36 - EF37 - EF37A - EF40 - EF86 is the near exact equivalent series that spring to mind for me.

EF50 - EF91 - EF80 are pretty similar.

No doubt there are others.
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Old 26th Nov 2020, 5:25 pm   #5
Mr Moose
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Default Re: Valve equivalents - electrically

Hello,
The tube search section from radiomuseum.org https://www.radiomuseum.org/dsp_searchtubes.cfm
gives quite a lot of information such as different base, different heater voltage etc.
For example :- https://www.radiomuseum.org/tubes/tube_6k7g.html
Yours, Richard
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Old 26th Nov 2020, 6:42 pm   #6
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Default Re: Valve equivalents - electrically

There were some intriguing notes on substitutions in the original volume of the 'Mullard Maintenance Manual' for certain obsolete types. Some were verging on 'desperate' and would state 'change base/xx resistor/heater volts' and the like ( sometimes more than one ! ) no doubt to keep a set going at any cost.
There was indeed a '12V6' as I have some RCA samples.

Andy
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Old 26th Nov 2020, 7:22 pm   #7
Simon Gittins
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Default Re: Valve equivalents - electrically

A book was published during the war with a view to keeping sets working even if only on the local station.
Valve Replacement Manual For Radio Service Engineers Hardcover – 1 Jan. 1941
by A.C. And Arthur Woffenden Farnell (Author)
Doesn't seem available in the UK at the moment but worth looking out for.
https://www.amazon.co.uk/Valve-Repla.../dp/B001OZRSQY
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Old 26th Nov 2020, 7:47 pm   #8
barrymagrec
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Default Re: Valve equivalents - electrically

I have that book - 2nd edition 1943...It was my Dad`s.

Never found it that useful to be honest but I always had plenty of other data books available.
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Old 26th Nov 2020, 8:56 pm   #9
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Default Re: Valve equivalents - electrically

This discussion has prompted me to mention the long-obsolete Philco-badged PenDD61 , one of which I found last week whilst clearing some space in my less-than-pretty shed . Sadly , a basic test showed a very low gm !
It was actually a Mazda AC/2PenDD , but with a 6.3v. heater to match the American valves in a U.K. built set. It was said to be a "concession" to the B.V.A.
Or has someone been pulling my leg ?
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Old 26th Nov 2020, 9:48 pm   #10
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Default Re: Valve equivalents - electrically

In reality most valves used in domestic run of the mill applications will work given the right number of electrodes and about the same anode power rating and bias conditions (only really important for output jobs). The ECC85 used in VHF/FM sets is a bit of an exception, pushed to the limit is an understatement!
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Old 26th Nov 2020, 11:23 pm   #11
GMB
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Default Re: Valve equivalents - electrically

Many circuits will accept anything - but that is only like with transistors, where same basic kind is enough - because the circuit didn't rely on the exact parameters.

But as mentioned, some next generation valves were effectively the same electrodes mounted a different way. That should give a very close match.

I was hoping to find tables of this.
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Old 26th Nov 2020, 11:55 pm   #12
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Default Re: Valve equivalents - electrically

Radiomuseum's valve info provides some details of similar valves with different base/heater/envelope shape etc.

eg:

https://www.radiomuseum.org/tubes/tube_75.html
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Old 27th Nov 2020, 7:42 am   #13
Robert Gribnau
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Default Re: Valve equivalents - electrically

Maybe this is what you are looking for: https://frank.pocnet.net/vademecum0.html
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Old 27th Nov 2020, 9:11 am   #14
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Default Re: Valve equivalents - electrically

Brimar had the “Brimaraze” marketing information for valve substitution for obsolete or unobtainable valves. This from the Brimar manual no 7, they also had adverts with suggestions in WW.
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